9- fixed statistic on added linear constraints in propagation
10- keep flag rangedrowpropagated of linear and exactlinear constraints for probing bound changes to avoid duplicate constraints by ranged row propagation
11- define result of SCIPconsProp() also if no propagation callback is available
12- keep variable for impossible substitution in cardinality constraint presolving to avoid duplication error
13- fix locking of indicator variables associated with cardinality constraints
14- free hashmap in cardinality constraints if problem is freed before transforming
15- fix CONSGETVARS and CONSGETNVARS callbacks of cardinality constraint handler
16- correct integer variable offset when removing duplicate variables from xor constraint
17- add applied clique as constraint when reformulating a binary product to avoid problem relaxation
18- round coefficients when aggregating integer variables with epsilon coefficient tolerance to ensure consistency of integrality
19- in the components constraint handler, avoid solving last component as a subproblem if all others components were trivial
20- when solving a node is interrupted, create a node branched event for the artificial child node
21- add missing capture of binary variable in indicator constraint handler
22- disregard deletable flag in IIS generation to reenable removal of unused variables
23- restore infeasible original problem in IIS addition filter if interrupted or hitting a limit
24- fixed that SCIP did not catch Ctrl+C in concurrent mode
25- SCIPsolveConcurrent() now returns with an error when reoptimization is enabled, since the concurrent sub-solvers do not perform reoptimization and the combination could segfault after SCIPfreeReoptSolve()
26- fixed indexing in the heap implementation in Dijkstra's algorithm; behavior of heap was and is correct
27
28Build systems
29-------------
30
31- fixed that the doc target in cmake builds was not available when using -DBUILD_TESTING=OFF
32- add /bigobj compiler flag when compiling with cmake, MSVC, LPS=spx, and in debug mode
33
34Miscellaneous
35-------------
36
37- added DEBUGTOOL=perf option for check scripts to collect perf statistics (new sections @06, @09, @10), including computation and comparison of non-memory-stalling frequency-normalized time
38- check scripts now write available memory (kB) and the current cumulative CPU ticks (from /proc/stat) before and after the solve to the .out file (new sections @07 and @08)
39- allow to return SCIP_CONSADDED when propagating constraints
40- cardinality constraint handler now parses and writes the indicator variables
41
42@section RN1002 SCIP 10.0.2
43***************************
44
45Fixed bugs
46----------
47
48- an error is now produced if the emphasis settings in parameter files are wrong
49- propagate focus lower bound to child nodes to avoid outdated global lower bound
50- set small coefficients in SCIPvarGetActiveRepresentatives() to zero, in particular for (multi-)aggregations
51- avoid flattening multi-aggregations twice
52- fixed that inttobinary presolver kept trying to aggregate variables that were marked as not to be aggregated
53- provide memory allocation for implied integral binary and integer variables in dks heuristic to avoid data corruption
54- fixed that violations of nonlinear constraints were not registered with solutions, and so were not included in the overview printed by the checksol command of the SCIP shell
55- fixed failing assert when assembling data for writing of JSON statistics and no plugins were included for some plugin types
56- fixed a bug in sassy/dejavu by updating version
57- add missing library exports of SCIPchgVarLbGlobalExact(), SCIPchgVarUbGlobalExact(), SCIPinferVarLbConsExact(), and SCIPinferVarUbConsExact()
58- add prefix TNY_ for tnycthread functions in order to avoid name clash with POSIX threads functions
59- keep sanitizers enabled if only unsupported for some language in cmake
60- fixed that header files and library of exact LP solver interface (lpiexact) and header files of TPI were not installed by make install (non-cmake build)
61- fixed that C++14 may not have been enforced when compiling with CppAD or Boost with makefiles
62
63Miscellaneous
64-------------
65
66- check scripts can now copy solution files to check/results/, functional for CPLEX, GAMS, and SCIP for now; new option KEEPSOL to disable writing and keeping solution files
67
68@section RN1001 SCIP 10.0.1
69***************************
70
71Fixed bugs
72----------
73
74- fixed that parameters passed on as variadic arguments to SCIPsolveNLP() and SCIPsolveNlpi() were ignored when compiling with MS compilers without -Zc:preprocessor
75- make more CONOPT output available when verbosity level is set to 2
76- turn off detection of definitional constraints in CONOPT for now, to work around a related issue in CONOPT 4.39.0
77- fixed call of SCIPcreateConsBasicSOCNonlinear() with coefs being NULL, and fixed check for offsets being finite
78- avoid crash when initial IIS solve fails while reporting errors explicitly
79- fixed that variable removal in IIS cleanup tried to delete variables that were marked as not deletable
80- fixed that some IIS info messages were not using a user's message handler
81- fixed use of interactive option (-i) of AMPL interface
82- fixed failure in nl writing on big endian machines
83- correct memory reallocation in storeSubproblemMasterVar() of benders.c to avoid errors when freeing memory
84- also set real solution in SCIPsolSetValExact() to maintain approximation
85- handle exact solutions in SCIPsolCheckOrig(), SCIPcheckSolOrig(), and SCIPrecomputeSolObj() to correctly check exact initial solutions in SCIPtransformProb()
86- fixed calculation of Euclidean norm in calcEfficacyDenseStorage() for use in exact solving
87- removed unnecessary explicit linking of GMP library for exact solving mode unittests
88- fixed bug with changing the type of the slack variable in indicator constraints while copying
89- signal extreme estimations in timeSeriesEstimate() and skip pruning estimations in eventExecEstim() to avoid unstable restarting
90- fixed parallelism computation of dynamic cut selector to use Euclidean norm instead of unsupported argument
91- fixed that non-efficacious cuts were not filtered out before checking dynamic parallelism in dynamic cut selector
92- fixes in nauty.h for 32bit systems
93- fixed SCIPgetDualSolVal() for a linear constraint with a single variable
94- adjust conflictAnalyzeLP() to inability of row aggregation to handle a change in the number of variables
95- propagate child lower bounds back to focus node to ensure consistent lower bound tracking
96
97Miscellaneous
98-------------
99
100- updated ampl/mp to version 4.0.4
101- switch from GetTempPath2A to GetTempPathA in nl writer for Windows for broader compatibility
102
103@section RN1000 SCIP 10.0.0
104***************************
105
106Features and Performance Improvements
107-------------------------------------
108
109### Exact Solving
110- added numerically exact solving mode for mixed-integer linear programs to the core framework including certification of branch-and-bound phase
111- core extensions:
112 - new wrapper struct SCIP_RATIONAL for rational arithmetic currently based on Boost, GMP, and MPFR
113 - new data structure SCIP_LPEXACT for handling rational LP relaxation and computing safe dual bounds
114 - new interfaces to exact LP solvers SoPlex and QSopt_ex
115 - safe dualproof version of conflict analysis
116 - new data structure SCIP_CERTIFICATE for certificate printing/proof logging
117- new plugins:
118 - new constraint handler "exactlinear" for handling linear constraints with rational data
119 - new constraint handler "exactsol" to post-process and repair solutions from floating-point heuristics
120- plugins revised for numerically exact solving mode:
121 - adjusted readers for MPS, LP, CIP, OPB/WBO, and ZIMPL files
122 - extended presolver "milp" to perform rational presolving with PaPILO
124 - extended Gomory cut separator to separate and certify numerically safe MIR cuts
125 - adjusted all primal heuristics (except for five dedicated MINLP heuristics)
126- new interfaces to exact LP solvers SoPlex and QSopt_ex
127
128### Symmetry Handling
129- added more techniques to handle reflection symmetries, in particular, for orbitopes with column reflections and matrices whose rows and columns can be permuted by a symmetry
130- Dejavu can be used to compute symmetries; the source code is shipped with SCIP and incorporates sassy
131- implemented symmetry detection callbacks for disjunction and superindicator constraint handlers
132- detailed information about applied symmetry handling techniques can be printed to the terminal
133- improve memory usage by introducing different constraint handlers for full orbitopes and packing/partitioning orbitopes
134- symmetry detection no longer treats implicit integer variables separately, but computes symmetries based on the variable type inferred from variable bounds and implied integrality
135- extended the statistics to also include information about the number of variables (per type) affected by symmetry
136- implemented method to compute new permutations from a given list of symmetry group generators
137- cons_orbisack, cons_orbitope_full, cons_orbitope_pp, and cons_symresack now try to replace the stored aggregated variables by active ones at the end of presolving;
138 this should reduce the size of copies of the presolved problem
139- simplified symmetry detection graphs in case all edges have the same color
140
141### Presolve
142- distinguish implicit integrality of variables into strong and weak type, depending on whether integrality is implied for all feasible or only at least one optimal solution
143- added a new presolver "implint", which detects implied integral variables by detecting (transposed) network submatrices in the problem; for now, this plugin is disabled by default
144- added support for (transposed) network matrix detection
145- allow multi-aggregation of unbounded slack variables, which may enable more bound tightening due to a reduction in the number of unbounded variables
146- resolve all fixings in xor constraints also for an available integer variable
147
148### Conflict Analysis
149- added generalized resolution conflict analysis that operates directly on linear constraints instead of conflict graphs
150- disabled dualsol and dualray conflict upgrades to maintain conflict store
151- apply general conflict upgrades in conflict store
152
153### Cutting Planes
154- added a new separator "flower" to generate flower cuts from AND constraints and nonlinear product expressions
155- added functionality to deal with hypergraphs by means of efficient access to vertices, edges, and intersections edges
156
157### Primal Heuristics
158- added decomposition kernel search (DKS) heuristic (disabled by default), which implements a kernel search framework;
159 it can be used both as a construction heuristic as well as an improvement heuristic; existing decomposition information can be utilized
160- reduced maximal fraction of diving LP iterations relative to total node LP iterations
161
162### Branching
163- added a dynamic max-lookahead criterion for strong branching; a probability distribution is fitted to the observed candidate gains and
164 evaluating further candidates stops when the expected tree-size reduction no longer justifies the LP evaluation cost
165- added new fields in history to store ancestral pseudo cost updates, used in the pseudo costs branching rule to compute discounted pseudo costs
166
167### Nonlinearity
168- added an interface to the NLP solver CONOPT
169- implemented columnwise Jacobian sparsity computation in the NLP oracle
173- added the possibility to search for irreducible infeasible subsystems (IIS)
174- added new plugin type for finding irreducible infeasible subsystems (IIS)
175- new iisfinder plugin "greedy", which implements a greedy addition and deletion based algorithm with dynamic batch sizing
176
177### Benders' Decomposition
178- when solving a problem with additional decomposition information (for example, when reading a DEC file) and enabling decomposition/applybenders,
179 the problem is now solved in a Benders' decomposition relaxator; instead of decomposing the original SCIP instance, the relaxator builds the decomposed problem in
180 sub-SCIPs and solves it via default Benders' Decomposition; a solution to the original (undecomposed) problem is now made available by the relaxator;
181 the SCIP shell dialog "display statistics" now also prints the statistics from solving the Benders' decomposition in the relaxator
182- adds objective types for Benders' decomposition; the choices are to sum the subproblems objectives (classical approach) and to use the maximum of the subproblems objectives
183- the linking master variables for each Benders' decomposition subproblem are now stored; these can be accessed for the generation of cuts and setting up the subproblems
184
185### Reading and Writing
186- added a new data structure SCIP_DATATREE that holds serializable data and a function to export to a JSON file
187- added ability to collect statistics from tables in a SCIP_DATATREE and write out as JSON file;
188 dialog write statistics now writes a JSON file if name of file to write ends with .json
189- added writing support for AMPL NL writer: currently only general and specialized linear and nonlinear constraints can be written
190- added support for AND-constraints to GAMS writer
191- simplify expressions of nonlinear constraints in MPS and LP writing to increase chance that they are recognized as quadratic
192
193### Applications
194- New application "PBSolver" to solve pseudoboolean instances in OPB and WBO format while complying with PB competition rules
195- Coloring: new parameter branching/coloring/strategy to choose the least/most fractional variable for branching
196
197### Miscellaneous
198- do not allow non-root restarts when no global fixings were found
199- reimplemented SCIPvarGetActiveRepresentatives() by using dense arrays to avoid repeated resorting
200- avoid unnecessary calls of constraint handlers components, benders, benderslp, propagator genvbounds, and heuristics ofins, subnlp, nlpdiving, indicator
201- inlined SCIPgetStatus() to reduce computational overhead
202- variable data pointer are now copied if no copy routine was supplied
203- add check that parameter value pointers are unique, i.e., no two are the same
204
205Interface changes
206-----------------
207
208### Deprecations
209
210- The variable type \ref SCIP_VARTYPE_IMPLINT is deprecated in favor of a new enum \ref SCIP_IMPLINTTYPE that indicates if a
211 variable is implied integral, independent of the variable type.
212 The problem variable arrays is still sorted as:
216 where the implied integral subsection is now subdivided into 3 parts (left to right):
217 ```
218 | binary implied integral | integer implied integral | continuous implied integral |
219 ```
220 SCIP 10 still supports using `SCIP_VARTYPE_IMPLINT` for backward compatibility, see SCIPcreateVar() and SCIPchgVarType() for more details.
221 SCIP 11 will remove `SCIP_VARTYPE_IMPLINT`.
222- SCIPsubversion() is deprecated and will be removed
223
224### New and changed callbacks
225
226- added SCIP_DECL_IISFINDERCOPY(), SCIP_DECL_IISFINDERFREE(), and SCIP_DECL_IISFINDEREXEC() for iisfinder implementations
227- added a new callback SCIP_DECL_TABLECOLLECT() for the table plugin that collects the data for the specific statistics table in a SCIP_DATATREE object
228- for a table plugin, only one of the callbacks SCIP_DECL_TABLECOLLECT() or SCIP_DECL_TABLEOUTPUT() needs to be implemented, but implementing both is preferred;
229 if SCIP_DECL_TABLEOUTPUT() is omitted, then SCIP tries to print a table from the data given by SCIP_DECL_TABLECOLLECT()
230- the callback SCIP_DECL_EXPRINTEGRALITY(), which returns the integrality of an expression, had its fourth argument changed from `SCIP_Bool*` to `SCIP_IMPLINTTYPE*` to represent implied integrality in nonlinear expressions,
231 that is, an implied integral type of an auxiliary variable if the expression were assigned to it
232- added argument `filename` to the SCIP_DECL_READERWRITE() callback in the 4th position
233- the callback SCIP_DECL_READERWRITE() is equipped with `objoffset`, `objscale`, `objoffsetexact`, and `objscaleexact` as arguments 9 through 12 to write the exact objective offset and scale in exact mode
234
235### Deleted and changed API functions
236
237- SCIPgetProbvarLinearSum(): remove parameter `mergemultiples`, which is now automatically true with the new implementation of SCIPvarGetActiveRepresentatives()
238- `SCIPcreateRow*()`, SCIPaddVarToRow(), SCIPaddVarsToRow(), SCIPaddVarsToRowSameCoef() can now only be called in the solving stage, because otherwise the LP is not yet available and the row data is invalid
239- SCIPcreateConsPseudobooleanWithConss(), SCIPcreateConsPseudoboolean(), and SCIPcreateConsBasicPseudoboolean(): removed `intvar` from arguments because the non-linear objective reformulation with pseudoboolean constraints did not work
240- SCIPcleanupConssLinear() and SCIPcleanupConssKnapsack(): added argument `ndelconss` to directly delete empty redundant constraints before creating problem matrix
244- SCIPpermuteProb(): argument `permuteimplvars` has been replaced by new arguments `permutebinimplvars`, `permuteintimplvars`, and `permutecontimplvars`
245- SCIPgetLPBranchCands(): implied integral variables with integrality constraints are included in `nlpcands` count and stored at the end of `lpcands`
246- SCIPgetNLPBranchCands(): implied integral variables with integrality constraints are included
247- SCIPgetSolVarsData(): argument `nimplvars` has been replaced by new arguments `nbinimplvars`, `nintimplvars`, and `ncontimplvars`
249- SCIPcreateVar() (temporarily for SCIP 10 only): attempting to create a variable with type \ref SCIP_VARTYPE_IMPLINT creates a variable of type \ref SCIP_VARTYPE_CONTINUOUS and implied integral type \ref SCIP_IMPLINTTYPE_WEAK
250- SCIPchgVarType() (temporarily for SCIP 10 only): attempting to change a variable type to \ref SCIP_VARTYPE_IMPLINT leads to a call of SCIPchgVarImplType() with type \ref SCIP_IMPLINTTYPE_WEAK
251- `SCIPapplyBendersDecomposition()` has been removed; this was originally used to apply Benders' decomposition from a supplied decomposition structure; the application of Benders' decomposition now occurs in relax_benders
252- SCIPcalcMIR(), SCIPcutGenerationHeuristicCMIR(), SCIPcalcStrongCG(): replaced boolean argument `usevbds` by an integer argument `vartypeusevbds`, which indicates for which variables variable bound substitution should be performed
253- `SCIPchgAndConsCheckFlagWhenUpgr()`, `SCIPchgAndConsRemovableFlagWhenUpgr()`: removed to keep upgrade flags consistent; use SCIPconsAddUpgradeLocks() to control upgrades instead
254- SCIPaddConflict(): argument `cons` changed to type `SCIP_CONS**` to release the conflict constraint in a clean way
255- SCIPprintOrigProblem() and SCIPprintTransProblem(): moved declaration moved from scip_solvingstats.h to scip_prob.h
256- `SCIPnlpiOracleGetJacobianSparsity()`: renamed to SCIPnlpiOracleGetJacobianRowSparsity() and added arguments `colnlflags` and `nnlnz`
270 `SCIPbendersApplyDecomposition()`, `SCIPgetExprsdataBilinear()`, `SCIPgetVarCoefChg()`, `SCIPvarGetOrigIndex()`, `SCIPallocateSymgraphConsnodeperm()`, `SCIPwriteSto()`: removed the declaration because there was no implementation
271
272### New API functions
273
274Exact Solving:
275- SCIPenableExactSolving(): enable and disable exact solving mode; see below for a list of many new API functions added to support exact solving
276- `SCIPrational*()`: create and compute with rational numbers
277- SCIPintervalSetRational(): compute interval of rational number
278- SCIPstrToRationalValue(), SCIPrationalStrLen(), SCIPrationalToString(): handle string conversion of a rational number
279- SCIPrationalChgInfinity(), SCIPrationalGetInfinity(): handle infinity threshold of rational numbers
280- `SCIPrationalarray*()`: create and handle rational arrays
281- SCIPisExact(): query whether exact solving is enabled
282- SCIPisCertified(): query whether certification is enabled
283- `SCIPcertify*()`, `SCIP*Certificate()`: support proof logging/certificate generation
284- `SCIP*MarkExact()`: mark plugins as safe to use in exact solving mode
285- `SCIP*IsExact()` : query whether objects are ready for exact solving
286- SCIPincludeConshdlrExactLinear(): include the constraint handler for exact linear constraints
287- `SCIP*ExactLinear()`: create, query, and modify an exact linear constraint
288- SCIPconsGetLhsExact()`, SCIPconsGetRhsExact(), SCIPgetConsValsExact(): query exact sides and coefficients of a linear constraint
289- `SCIPmatrix*Exact()`: query matrix information in rational arithmetic
290- SCIPaddVarExactData(): add exact data to an existing variable
291- `SCIPvarGet*Exact()`: query variable information in rational arithmetic
294- SCIPlpExactDiving(): query whether exact LP is in diving mode
295- SCIPlpExactIsSolved(): query whether the exact LP is solved
296- SCIPwriteLPexact(): write the exact LP
297- `SCIPcolExact*()`, `SCIProwExact*()`: handle the exact LP columns and rows
298- `SCIPlpiExact*()`: handle the exact LP interface
299- SCIPgetNExactLPs(): query the number of exact LP solves
300- SCIPgetLPExactSolstat(), SCIPgetLPExactObjval(): query solution status and objective value of the exact LP
301- SCIPaddOrigObjoffsetExact(), SCIPgetOrigObjoffsetExact(): add and query exact objective offset of the original problem
302- `SCIP*Sol*Exact()`: create and handle exact solutions
303- SCIPsolOrigAddObjvalExact(): add to exact objective of original solution
304- SCIPincludeConshdlrExactSol(): include the exact post-processing for solutions
305- `SCIP*Row*Exact*()`: create and handle exact LP rows
306- `SCIPaggrRow*Safely()`: compute safe real row aggregation
307- SCIPallowNegSlack(): query whether negative slacks are allowed
308- SCIPbranchLPExact(): branch exactly on the LP solution
309- SCIPeventGetOldboundExact(): query exact old bound for a bound change event
310- SCIPcalcIntegralScalarExact(): compute a scalar so that all given values become exactly integral
311- SCIPnodeGetLowerboundExact(): query the exact lower bound of a node
312- SCIPgetCutoffboundExact(), SCIPgetLowerboundExact(), SCIPgetUpperboundExact(), SCIPgetDualboundExact(), SCIPgetPrimalboundExact(): query exact best bounds on optimal value
313- SCIPvalidateSolveExact(): validate the exact solve
314
315Implicit Integrality:
316- SCIPincludePresolImplint(): include the new implied integral presolver
317- SCIPcreateVarImpl(), SCIPcreateObjVarImpl(): behave identically to SCIPcreateVar() and SCIPcreateObjVar(), respectively, but have an additional argument for the new implied integral type flag (8th position)
318- SCIPchgVarImplType(), SCIPvarGetImplType(), SCIPvarIsImpliedIntegral(), SCIPcolIsImpliedIntegral(): control and query implied integrality
319- SCIPvarIsNonimpliedIntegral(): query whether a variable is integral but not implied integral
320- SCIPgetNOrigBinImplVars(), SCIPgetNOrigIntImplVars(), SCIPgetNOrigContImplVars(): query the number of implied integral variables of each type in original problem;
321 note that SCIPgetNOrigBinVars(), SCIPgetNOrigIntVars(), and SCIPgetNOrigContVars() no longer include the implied integral variables in their counts
322- SCIPgetNBinImplVars(), SCIPgetNIntImplVars(), SCIPgetNContImplVars(): query the number of implied integral variables of each type in current problem;
323 note that SCIPgetNBinVars(), SCIPgetNIntVars(), and SCIPgetNContVars() no longer include the implied integral variables in their counts
324- SCIProwGetNumImpliedIntCols(): query number of implied integer columns in a row
325- SCIPvarsCountTypes(): determine the variable type count distribution for an array of variables
326- SCIPeventGetOldImplType(), SCIPeventGetNewImplType(): query implication type change for the new event \ref SCIP_EVENTTYPE_IMPLTYPECHANGED
327- SCIPexprGetIntegrality(): provides information about the presence of weakly implied integral variables, in addition to the existing function SCIPexprIsIntegral()
331- SCIPdisplaySymmetryGenerators(), SCIPdialogExecDisplaySymmetry(): display generators of symmetry group
332- SCIPclearSymgraph(), SCIPcopySymgraphAsSubgraph(): clear and copy a symmetry detection graph, respectively
333
334Conflict Analysis:
335- SCIPgetNResConflictConssApplied(): return the number of generalized resolution conflict constraints added to the problem
336- SCIPaddConsUpgrade(): add constraint upgrades while informing the conflict store
337
338Branching:
339- SCIPhistoryUpdateAncPseudocost(), SCIPvarUpdateAncPseudocost(): update the ancestral pseudo cost fields in variable history
340- SCIPhistoryGetAncPseudocost(), SCIPhistoryGetAncPseudocostCount(), SCIPhistoryIsAncPseudocostEmpty(), SCIPgetVarAncPseudocostVal(), SCIPvarGetAncPseudocost(): retrieve values related to ancestral pseudo cost fields in variable history
342- SCIPboundchgGetLPSolVal(): access LP solution value in the branching data of a bound change
343
344Cutting Planes:
345- SCIPincludeSepaFlower(): include the new flower cut separator
346- SCIPconsCreateRow(): to create and return the row of a linearly representable constraint
347- SCIPcreateRowKnapsack(), SCIPcreateRowLinear(), SCIPcreateRowLogicor(), SCIPcreateRowSetppc(), SCIPcreateRowVarbound(): create and get the row of linearly representable constraints
348
349Benders' Decomposition:
350- SCIPincludeRelaxBenders(): include the Benders' decomposition relaxator
351- SCIPgetMasterProblemRelaxBenders(): retrieve master problem SCIP instance from the Benders' decomposition relaxator
352- SCIPbendersGetSubproblemMasterVars(), SCIPbendersGetNSubproblemMasterVars(), SCIPbendersGetSubproblemMasterVarsData(): get the linking master variables for each subproblem and details about the number of binary and integer variables
353- SCIPsetBendersObjectiveType(), SCIPbendersGetObjectiveType(): set and get the objective type for the aggregation of the Benders' decompostion subproblems
354- SCIPbenderGetMasterAuxiliaryVar(): get master auxiliary variable
355- SCIPfreeReaderdataCor(), SCIPfreeReaderdataTim(), SCIPfreeReaderdataSto(): free the data for the COR, TIM, and STO readers, respectively; these readers are all used when reading an SMPS instance
368 SCIPhypergraphOverlapsEdgesGetAtIndex(), SCIPhypergraphVertexOverlapsFirst(), SCIPhypergraphVertexOverlapsBeyond(), SCIPhypergraphVertexOverlapsGetAtIndex(): query information about vertices, edges, and overlaps as well as their incidences
369
370Network Matrix:
371- SCIPnetmatdecCreate(), SCIPnetmatdecFree(): create and delete a network matrix decomposition
372- SCIPnetmatdecTryAddCol(), SCIPnetmatdecTryAddRow(): add columns and rows to a matrix decomposition
373- SCIPnetmatdecContainsRow(), SCIPnetmatdecContainsColumn(): check if a matrix decomposition contains the given row or columns
374- SCIPnetmatdecRemoveComponent(): remove connected components from a matrix decomposition
375- SCIPnetmatdecCreateDiGraph(): expose underlying digraph of matrix decomposition
376- SCIPnetmatdecIsMinimal(), SCIPnetmatdecVerifyCycle(): check whether certain invariants of a matrix decomposition are satisfied and used in tests
377
378Solve Statistics:
379- functions to create, modify, and free SCIP_DATATREE objects and to print as JSON or table (see pub_datatree.h and scip_datatree.h)
380- `SCIPcollect*Statistics()`: for every `SCIPprint*Statistics()` in scip_solvingstats.h
381- SCIPprintStatisticsJson(): output a JSON string of the table statistics data
382
383Nonlinearity:
384- SCIPincludeNlpSolverConopt(), SCIPsetLicenseConopt(), SCIPgetSolverNameConopt(), SCIPgetSolverDescConopt(), SCIPisConoptAvailableConopt(): interact with the new CONOPT interface
385- SCIPnlpiOracleGetConstraintLinearCoef(): get a linear coefficient of a variable in a given constraint in the NLP oracle
386- SCIPnlpiOracleGetJacobianColSparsity(): get the column-wise sparsity pattern of the Jacobian from the NLP oracle
387- SCIPnlpiOracleGetObjGradientNnz(): get indices of nonzeroes in the objective gradient
388- `src/objscip/objexprhdlr.h`: C++ interface for expression handlers
389
390Miscellaneous:
391- SCIPsortRealPtrPtr(), ..., SCIPsortDownIntIntIntReal(): new sorting functions
392- `SCIPdebugClearSol()`: clear the debug solution
393- SCIPdialogIsHidden(), SCIPdialogSetHidden(): determine whether a dialog should be hidden in help list
394- SCIPstatusName() to get a string representation of SCIP_STATUS
395- SCIPconshdlrSetNeedsCons(): set whether constraint handler callbacks should also be called if there are no constraints
396- SCIPpropSetTimingmask(): set timing mask of a propagator
398- SCIPvarGetMinAggrCoef(), SCIPvarGetMaxAggrCoef(): get bounds on absolute aggregation coefficients for a loose variable
399- SCIPisVarAggrCoefAcceptable(): check whether bounds on aggregation coefficients would exceed thresholds when using a loose variable in another aggregation
400- SCIPgetNRootIntFixings(): retrieve the number of integer fixings at the root node
401- SCIPcollectMemoryGarbage(): explicitly trigger garbage collection on block memory; before SCIP 10, this was done in SCIPtransformProb()
402
403### Data Structures
404
405\attention changed the numeric values in the \ref SCIP_STATUS enum
406
407- added struct \ref SCIP_RATIONAL for rational number arithmetic
408- added struct \ref SCIP_LPEXACT and many further data structures to support exact solving mode
410- added struct \ref SCIP_DATATREE to model generic serializable data; new enum \ref SCIP_DATATREE_VALUETYPE
411
412### Changes in Preprocessor Macros
413
414- `SCIP_EVENTTYPE_TYPECHANGED`: no longer generated if a variable becomes implied integral
415- `SCIP_EVENTTYPE_IMPLTYPECHANGED`: new event that is generated if a variable is declared implied integral, this event is included in the set \ref SCIP_EVENTTYPE_VARCHANGED
416- `SCIP_EVENTTYPE_DUALBOUNDIMPROVED`: new event that is generated whenever the global dual bound is improved
417- `SCIP_EVENTTYPE_GAPUPDATED`: new event mask for catching updates in primal or dual bound
418- `SCIP_PROPTIMING_NONE`: new propagator timing for never calling a propagator
419- `SCIP_HEURTIMING_NONE`: new heuristic timing for never call a primal heuristic
420- `strcasecmp`, `strncasecmp` (Windows builds): removed `#define` from scip/def.h; use SCIPstrcasecmp() and SCIPstrncasecmp() instead
427- `help <command>` now allows to display information on specific command
428- allow to hide certain commands in the help list
429- added the (hidden) command "exit" to exit the shell
430- added command `iis` to create an infeasible subsystem
431- added `write/iis` dialog to write out the infeasible subsystem to file
432- added `display/iis` dialog to write out the infeasible subsystem to console
433
434### Changed parameters
435
436- `heuristics/scheduler/heurtimelimit` removed to avoid indeterministic behavior of scheduler heuristic, uses main time limit instead
437- removed parameters `constraints/orbitope/checkpporbitope`, `constraints/orbitope/sepafullorbitope`, `constraints/orbitope/forceconscopy`, which became superfluous
438- removed `reading/gmsreader/signpower`
439- removed `benders/default/numthreads`: multi-threading support for Benders' decomposition has been temporarily disabled
440- restricted range of parameter `propagating/symmetry/sstleadervartype` to [1,7]; its new default value is 6
441- `propagating/∗/timingmask` extended by setting 0 to disable propagators completely
442- changed defaults of `constraints/components/propfreq` and `constraints/components/maxdepth` to -1 and 2147483647, respectively, to avoid unnecessary calls of components propagator by default
443- changed frequencies for the following heuristics: shifting, gins, crossover, rins, randrounding
444- changed default `maxlpiterquot` to 0.05 for all LP diving heuristics and feaspump, whereas adaptivediving uses 0.15 and rootsoldiving remains at 0.01
445- changed default of `presolving/restartminred` to 0.05
446- changed default of `presolving/immrestartfac` to 0.05
448- updated description of parameter `misc/usesymmetry`
449
450### New parameters
451
452- `exact/enable`: enable exact solving mode
453- `exact/improvingsols`: whether only improving exact solutions should be considered
454- `exact/safedbmethod`: method of safe dual bounding
455- `exact/interleavedbstrat`: interleaving strategy between safe dual bounding and exact LP solving
456- `exact/psdualcolselection`: project-and-shift strategy of dual column selection
457- `exact/cutapproxmaxboundval`: maximal absolute bound for which coefficients in exact cuts should be approximated
458- `exact/cutmaxdenom`: maximal denominator of coefficients in approximating exact cuts
459- `exact/allownegslack`: whether negative slack variables in exact Gomory cuts should be used
460- `exact/lpinfo`: whether the exact LP solver should display status messages
461- `constraints/exact{linear,sol}/{sepafreq,propfreq,proptiming,eagerfreq,maxprerounds,delaysepa,delayprop,presoltiming}`: functionality of constraint handlers exactlinear and exactsol
462- `constraints/exactlinear/sortvars`: whether binary variable coefficients should be sorted with decreasing absolute value in exactlinear constraints
463- `constraints/exactlinear/{tightenboundsfreq,propcont,limitdenom,boundmaxdenom}`: propagation of exactlinear constraints
464- `constraints/exactlinear/{maxrounds,maxroundsroot,maxsepacuts,maxsepacutsroot}`: separation of exactlinear constraints
465- `constraints/exactsol/solbufsize`: size of solution buffer in exactsol handler
466- `constraints/exactsol/{minimprove,checkfpfeasibility,checkcontimplint,abortfrac,unfixfrac}`: solution processing in exactsol handler
467- `constraints/exactsol/maxstalls`: maximal number of consecutive unsuccessful reparations in exactsol handler
469- `branching/pscost/discountfactor`, `branching/relpscost/discountfactor`: discount factor for ancestral pseudo costs in pscost and relpscost branching rules
470- `branching/collectancpscost`: enable/disable recording of ancestral pseudo costs
472 configure the dynamic max-lookahead criterion for strong branching: enable flag, fraction threshold, distribution choice, and minimum sample size
473- `constraints/cumulative/maxtime`: limit the time horizon and avoid integer overflow for unbounded variables
474- `constraints/orbitope_full/forceconscopy`, `constraints/orbitope_pp/forceconscopy`: whether non-model constraints of type full orbitope and packing/partitioning orbitope are copied to sub-SCIPs, respectively
475- `propagating/symmetry/handlesignedorbitopes`: whether to apply special symmetry handling techniques for orbitopes whose columns can be (partially) reflected
476- `propagating/symmetry/usesimplesgncomp:` whether symmetry components all of whose variables are simultaneously reflected by a symmetry shall be handled by a special inequality
477- `propagating/symmetry/dispsyminfo`: whether to print information about applied symmetry handling methods
478- `propagating/symmetry/nautymaxlevel`: limit on depth level of Nauty's search tree
479- `presolving/implint/convertintegers`: whether implied integrality should also be detected for enforced integral variables
480- `presolving/implint/columnrowratio`: ratio of rows/columns where the row-wise network matrix detection algorithm is used instead of the column-wise network matrix detection algorithm
481- `presolving/implint/numericslimit`: limit for absolute integral coefficients beyond which the corresponding rows and variables are excluded from implied integrality detection
482- `write/implintlevel`: whether integrality constraints should be written for implied integral variables (regarded by cip, mps, lp, rlp, pip, fzn, and gms writers)
483- `iis/∗`
484- `presolving/milp/enablecliquemerging`: whether to enable clique merging in PaPILO
485- `presolving/milp/maxedgesparallel`: maximal number of edges in the parallel clique merging graph
486- `presolving/milp/maxedgessequential`: maximal number of edges in the sequential clique merging graph
487- `presolving/milp/maxcliquesize`: maximal size of cliques considered for clique merging
488- `presolving/milp/maxgreedycalls`: maximal number of greedy max clique calls in a single thread
490- `relaxing/benders/continueorig`: whether original problem should continue solving after the completion of the Benders' decomposition algorithm in the Benders' relaxator, if the problem is not solved to optimality
491- `relaxing/benders/nodelimit`: node limit for the Benders' decomposition master problem in the Benders' relaxator; by default the limits from the original SCIP instance are copied
493- `lp/minsolvedepth`: lower bound on the depth at which LPs are solved
494- `reading/opbreader/maxintsize`: maximal intsize above which an OPB instance is rejected
495- `reading/nlreader/binary`, `reading/nlreader/comments`: adjust writing of `nl` files
496- `nlpi/conopt/priority`: priority of the CONOPT NLP solver
497- `randomization/randomseedshiftmultiplier`: multiplier for the shift set by `randomization/randomseedshift`;
498 the shift is multiplied by (6*`randomseedshiftmultiplier`+1), with the default value for `randomseedshiftmultiplier` set to 10 now;
499 this default value is expected to change with every major release; setting the parameter to 0 restores SCIP 9 behavior
500
501### Other Changes
502
503- removed LP solver interface `lpi_spx1`, which used the old SoPlex interface; renamed `lpi_spx2` to `lpi_spx`
504- removed `cons_abspower.{h,c}`, `cons_quadratic.{h,c}`, and `cons_soc.{h,c}`
505
506Build system
507------------
508
509- new option `SYM=dejavu` to choose Dejavu for computing symmetries
510- changed the default for `TPI` to `tny`
511- added build flag `CHECKSTAGE=auto` to control stage checks in API function calls
512- removed `LPS` options `spx1` and `spx2`, only `LPS=spx` is available to select SoPlex now
513- removed previously deprecated `PARASCIP` option, use `THREADSAFE=false` instead to disable thread-safety
514
515### Makefile
516
517- added build flag `EXACTSOLVE=<true|false|auto>` to turn exact solving mode on, off, or turn it on if all necessary dependencies are available
518- added build flag `MPFR` (default: false) to link with the multiprecision floating-point library, needed when SoPlex is also built with `MPFR=true` for precision boosting in rational solving mode
519- added build flag `CONOPT` (default: false) to link to the CONOPT NLP solver
520- link-time-optimization can be enabled on Linux and macOS with gcc and clang by setting `LTO=true`, default is false
521- revised `SANITIZE` options: removed `SANITIZE=full`, added `SANITIZE=thread`, `SANITIZE=address`, and `SANITIZE=memory` to enable thread, address, and memory sanitizers, respectively, in addition to undefined behavior sanitizer;
522 changed default to `SANITIZE=false`
523- default settings for makefile variables in `make.project` are now only used if variable hasn't been set already
524- the symlink `$(LIBDIR)/include/papilo` should now point to the `src` subdirectory of a PaPILO repository or the headers directory of a PaPILO installation without TBB; pointing to the directory of a PaPILO repository still works, but is deprecated
525- removed option to link TBB library, as this is not used by default when PaPILO has not been built via cmake (use `USRCXXFLAGS=-DPAPILO_TBB USRLDFLAGS=-ltbb` to enable TBB for PaPILO)
526- `LPS=spx` is no longer mapped to `LPS=spx2`, which changes the name of the generated LPI libraries and binaries when using SoPlex
527- removed `OPENSOURCE` flag
528
529### Cmake
530
531- added build flag `EXACTSOLVE=<on|off|auto>` to turn exact solving mode on, off, or turn it on if all necessary dependencies are available
532- added build flag CONOPT (default: off) to link to the CONOPT NLP solver and variable `CONOPT_DIR` to specify the path to CONOPT
533- link-time-optimization can be enabled if supported by compiler by using `-DLTO=on`, default is `off`
534- replaced `SANITIZE_XYZ=(on|off)` options by `SANITIZE=(on|off|thread|address|memory)`;
535 undefined behavior sanitizer is always enabled if not `SANITIZE=off` (the default)
536- increased minimal required cmake version to 3.11
537- scip-config.cmake now defines a variable `SCIP_COMPILE_FLAGS`, which could be used to compile code that builds against SCIP via cmake;
538 currently, this only passes on the sanitizer flags that were used to build `libscip`
539- removed automatic download and build of Bliss during cmake configuration when `-DSYM=(s)bliss`;
540 a Bliss installation from https://github.com/scipopt/bliss can be specified with `-DBLISS_DIR`
541- removed option `LEGACY`
542
543Fixed bugs
544----------
545
546- fixed bug related to unreleased data for the Benders' decomposition framework; when reading an SMPS file and applying
547 Benders' decomposition, data is created that was not correctly released; also, data within the Benders' decomposition
548 framework was not appropriately reset; the data is now released/reset as expected
549- to fix a bug where duplicate cuts from different constraint handlers were not recognized, `SCIPrealHash()` was changed
550 to be stable around shortly representable numbers, and a numerical tolerance for comparing cutting plane efficacy for the aggregation
551 separator is introduced
552- accept fractional continuous implied integral variables in heuristic "completesol"
553- invalidate activity with contradicting infinity contributions
554- avoid integer overflow in cumulative constraints triggered by unbounded variables, see new parameter `constraints/cumulative/maxtime`
555- allow negative update in SCIPconsAddUpgradeLocks() to unlock constraint upgrade
556- fixed memory leaks when LP, MPS, and OPB/WBO readers abort unsuccessfully
557- removed erroneous catching of objective-changed events in intobj separator; instead, the separator no longer executes within probing with changed objective function
558- propagator dualfix no longer fixes variables to infinity to avoid issues when transferring the solution to the original problem
559- track and check bounds on the coefficients that is used for a variable in aggregations of other variables to improve numerical stability
560- corrected the upgrade of full orbitopes to packing/partitioning orbitopes in case the orbitopal symmetries form a proper subgroup of a component's symmetry group
561- aggregate integer variable to not in clique variable in cliquePresolve() of xor constraints to avoid infeasible solutions
562- fixed memory leak in dynamic partition search primal heuristic
563- fixed issue with file existence check in XML parser when SCIP was build with ZLIB support on Windows
564- fixed thread-safety issue when using CppAD and user-defined expression handler
565- fixed typo in `#pragma` directive of redistributed nauty.h
566
567Miscellaneous
568-------------
569
570- removed 4th number in SCIP version; the new format is major.minor.patch
571- changed sassy to the version included in Dejavu
572- updated ampl/mp to v4.0.3
573- the CIP reader now sets an objective offset instead of adding a variable fixed to the objective offset
574- the solchecker tool has been extended for rational values
575- SCIPclassifyConstraintTypesLinear() classify a varbound only when a binary variable is present
576- the internal limit `MAXGENNUMERATOR` has been increased to allow more generators of symmetry groups, especially for problems with many variables
577
578@page RN9 Release notes for SCIP 9
579
580@section RN924 SCIP 9.2.4
581*************************
582
583Fixed bugs
584----------
585
586- fixed bugs with counting changes in presolving of nonlinear and setppc constraints, which resulted in negative values
587- cut off dead end node to correctly track dual bound update during solving
588- no longer construct and flush the LP in SCIPwriteLP() and SCIPwriteMIP() to avoid unexpected side effects
589- apply multi-aggregations before detecting redundancy in propagation of varbound constraints to keep bound implications
590- skip bound changes when cutting off a branch-and-bound subtree
591- correct detection of doublelex matrices and their handling via orbitope constraints
592- skip attempting to free transformed problem if SCIPtransformProb() failed with an error in SCIPpresolve(), since freeing
593 the transformed problem is likely to fail as well
594- fixed memory leak in primal heuristic "scheduler" when there is a restart
595- fixed stopping when there is a candidate with a change in the LP bound for both children in strong branching of branch_fullstrong
596- fixed detection of sinks in varbound detection from cumulative constraints
597- fixed memory allocation when adding strong SBCs for enclosing orbit of symmetric subgroups (disabled by default)
598- free paths of branch-and-bound tree iteratively instead of recursively to avoid stack overflow
599- fixed rare invalid memory access when collecting symmetry information for indicator constraints
600- recompute activity bounds before checking infeasibility and redundancy in linear constraint presolving
601- skip integer variables with fractional value in reference solution when finding additional variable fixings in ALNS heuristic
602- fix call of SCIPaddExprsViolScoreNonlinear() with constant expressions (no variables)
603- fixed bug with concurrent solve w.r.t. variable indices that led to segmentation faults and fix termination test
604- adjust further bounds before checking feasibility in SCIPvarAddVlb() and SCIPvarAddVub() to detect integrality cutoff
605- fixed that the last fixed binary variable was not set after binary variables were created for linking constraints
606- fixed that when a linking constraint with only one binary variable was added during solving, it was not disabled
607- fixed set_search_limits call when using SYM=sbliss with an old patched Bliss version
608
609Build system
610------------
611
612### CMake
613
614- added workaround for recent ctest versions rejecting -R -default as arguments
615
616### Makefile
617
618- added experimental target to run cppcheck
619
620
621@section RN923 SCIP 9.2.3
622*************************
623
624Fixed bugs
625----------
626
627- avoid hashmap key error in removal of doubletons and singletons in dual presolve of setppc constraints by skipping tripleton locks
628- when upgrading to xor constraint require parity variable to be enforced integral
629- provide the depth of the applied effective root with SCIPtreeGetEffectiveRootDepth() to avert invalid globalization of constraint set changes
630- disable objective limit during lexicographic dual minimization to preserve feasibility status
631- declare infinite bound inference infeasible in SCIPinferVarLbCons() and SCIPinferVarUbCons() to maintain correct loose LP values
632- fixed update of consssorted flags in a variable expressions data when adding an additional constraint using this variable
633- corrected computation of number of variables affected by symmetry
634- fixed computation of symmetry group size
635- correct comparison conditions in checkRedundancySide() of cons_varbound.c to ensure pair redundancy
636- also for the initial LP solve force acceptance of Farkas row in SCIPlpGetDualfarkas() if all other means for obtaining a reliable Farkas proof have failed
637- avoid overwriting the cutoff flag in tightenCoefs(), preprocessConstraintPairs(), and applyFixings() of cons_varbound.c to reject infeasible solutions
638- fix memory leak in CppAD interface w.r.t. user expressions
639- adjust bound before checking feasibility in SCIPvarAddVlb() and SCIPvarAddVub() to detect integrality cutoff
640- choose incumbent solution as reference in varFixingsRins() and varFixingsDins() of ALNS heuristic to ensure integrality
641- consider variable type in selectInitialVariableRandomly() of GINS heuristic to count integral variables
642- correct fractionality sign when standardizing bounds in simplifyInequalities() of cons_linear.c
643
644Build system
645------------
646
647### CMake
648
649- disable setting the boolean variable MACOSX_RPATH to a string value to actually enable @rpath usage
650- define SOPLEX_NEEDED and ZIMPL_NEEDED to avoid syntax error in configuration file
651
652Miscellaneous
653-------------
654
655- when writing a problem with non-generic names, warnings are printed if variable or constraint names are not unique
656
657@section RN922 SCIP 9.2.2
658*************************
659
660Fixed bugs
661----------
662
663- fixed definition of slack variables of >= constraints and ranged rows in LP interface to Gurobi
664- free memory leaking singleton arrays for ignored variables in SCIPapplyHeurDualval()
665- use epsilon tolerance for bound implications of dual substitutions in dualPresolve() of cons_linear
666- fixed timeouts due to race conditions when using TPI=omp
667- fixed issues with indexing of concurrent solvers when a solver finishes (because SCIP is too fast) before others have been created when using TPI=tny
668- respect fixing if variable is declared binary in bounds section of mps file
669- fixed reading mps files with short row and column names and some fixed-form mps files with spaces in row names
670- force local bounds to adjusted value when fixing variable
671- adds missing NULL check for Benders' subproblems in feasalt cut
672- apply objective scale to pseudoboolean non-linear terms
673- impose pseudoboolean cost bound without intermediate casting
674- flatten aggregation graph before finishing presolve to accelerate evaluating an empty solution
675- respect fixed resultants in binvarGetActiveProbindex() of branch_relpscost
676- drop fixed resultants when copying pseudoboolean constraint
677- correct matrix entry when resolving aggregated variables in checkSystemGF2() of cons_xor
678- corrected symmetry detection graph of cons_and, cons_or, cons_xor, and cons_indicator
679- correct redundancy filter in consdataCreateRedundant() of cons_bounddisjunction
680- replaced unreliable comparison of node pointers by node numbers in prop_genvbounds
681- allocate memory for all integral variables in applyCliqueFixings() of heur_clique
682- fix conflict resolution for one particular case in cons_indicator
683- make interface to nauty thread safe
684- use relative epsilon tolerance to check Farkas row in SCIPlpGetDualfarkas() to avoid invalid cutoff
685- fixed bug with SOS2 constraints of size that avoided a correct enforcing
686
687Build system
688------------
689
690### Cmake
691
692- allow to set HIGHS_DIR via -D flag as well
693- reenable building and testing of SCFLP example
694- fixed that compiler flags for sanitizers were not used for compiling objects of SCIP library
695- prioritize local includes for unittests, examples, and applications to link the intended SCIP version
696- fix detection of Gurobi 11 and 12 libs on Linux
697
698### Makefile
699
700- fix use of SANITIZE=full for debug builds with GCC on Linux: removed -fsanitize=leak because it cannot be used together with -fsanitize=address
701- fix that make install SHARED=true missed to install libscipbase
702
703@section RN921 SCIP 9.2.1
704*************************
705
706Fixed bugs
707----------
708
709- apply same feasibility definition in PaPILO as in SCIP to avoid numerical inconsistencies
710- check variable cancellation in SCIPvarAddVlb() and SCIPvarAddVub() to avert wrong infeasibility
711- SCIPfreeReoptSolve() now also clears partial solutions
712- fixed bug in calculation of "fractionality score" for spatial branching candidates in cons_nonlinear
713- fixed bug with installing symmetry dialog in sub-SCIPs
714- added copy callbacks for presolvers dualagg and redvub, branching rules lookahead and cloud, primal heuristics dualval and repair, propagator nlobbt, and separators gauge and convexproj
715- respect maximal separation rounds setting by running remaining delayed separators in last round
716- replace terms consistently in applyFixings() of cons_linear to handle infinite aggregations
717
718Build system
719------------
720
721### Cmake
722
723- fix SCIP Optimization Suite build with -DSYM=(s)bliss and bliss being downloaded and built during configuration by cmake
724- fix use of a bliss cmake installation (from https://github.com/scipopt/bliss) specified via BLISS_DIR if -DSYM=(s)bliss
725
726### Makefile
727
728- the check/solchecker build can now use also GMP installations by Homebrew on macOS/arm64
729
730Miscellaneous
731-------------
732
733- the output precision for writing CIP/OPB files has been increased at several places for nonlinear constraints
734- the solchecker tool now also supports SCIP solutions without unknown or infinite values
735- generate an error if the same linear constraint is used by several indicator constraints
736
737@section RN920 SCIP 9.2.0
738*************************
739
740Features
741--------
742
743- added check for absolute and relative gap limits at end of synchronization in concurrent solving mode, in order to terminate earlier;
744 note that if the concurrent solve is stopped due to a gap limit, the "winner" solver will have an interrupted solution status and
745 its primal and dual bounds may not be the best possible ones (use SCIPgetConcurrentPrimalbound() and SCIPgetConcurrentDualbound() instead)
746- parse pseudoboolean constraint from CIP format (and add linear-"and"-reformulation)
747
748
749Performance improvements
750------------------------
751
752- reoptimization now also stores propagations from propagators if reoptimization/saveconsprop is enabled;
753 the parameter will be renamed to reoptimization/saveprop in a next major release
754- imposed stricter limits on the size of disconnected components which may be solved separately during presolve
755- use individual slack variables also for constraints indicated by a common binary variable to use tighter formulation by default
756- when computing symmetries using Nauty, iteration limits are now available to terminate Nauty early
757
758Fixed bugs
759----------
760
761- Benders' decomposition subproblems that are always infeasible are correctly handled and the complete problem is declared infeasible
762- skip linear constraint propagation if the residual activity bound cancels the side precision
763- correct bound tracking to make the evaluation of primal-dual-integrals work
764- skip aggregations on fixed variables in milp presolver to avoid errors for earlier versions of PaPILO
765- use indices of negation counterparts and accept fixings when ordering and-resultants of pseudoboolean constraints
766- update locks on model variables before removing pseudoboolean constraints in presolve
767- reformulate soft pseudoboolean constraints with linear constraints if the indicator decomposition is disabled
768- add workaround for recent HiGHS versions resetting the model status when changing the presolve option after a solve
769- avoid hashmap key error in removal of doubletons and singletons in dual presolve of setppc constraints by updating constraints and corresponding hashmaps after each multi-aggregation
770
771Interface changes
772-----------------
773
774### New API functions
775
776- added SCIPtpiIsAvailable() to check whether a working task processing interface is available (TPI != none)
777- added SCIPtpiGetLibraryName() and SCIPtpiGetLibraryDesc()
778- SCIPdelCons() can now also be called in SCIP_STAGE_TRANSFORMED
779- added SCIPstrcasecmp() and SCIPstrncasecmp() for case-insensitive string comparison
780- added SCIPbendersSubproblemsAreInfeasible() to return if at least one subproblem has been identified as being
781 infeasible prior to performing any variable fixing
782
783### New parameters
784
785- presolving/milp/abortfacexhaustive to control the abort threshold for exhaustive presolving in PAPILO
786- presolving/milp/abortfacmedium to control the abort threshold for medium presolving in PAPILO
787- presolving/milp/abortfacfast to control the abort threshold for fast presolving in PAPILO
788- constraints/components/maxcompweight to determine the maximum weight for a disconnected component that is solved during presolve
789- constraints/components/contfactor counts the contributing factor of a single continuous variables with respect to the weight limit specified by constraints/components/maxcompweight
790- constraints/indicator/usesameslackvar to decide whether the same slack variable should be used for indicators constraints with common binary variable
791- propagating/symmetry/nautymaxncells and propagating/symmetry/nautymaxnnodes to set iteration limits in Nauty (only available if build with SYM=nauty or SYM=snauty)
792
793### Changed parameters
794
795- presolving/milp/threads is now only available if PaPILO is built with TBB
796- changed default of numerics/recomputefac to 1e+6 to aim at relative epsilon precision
797
798Build system
799------------
800
801### Cmake
802
803- attempted to fix detection of CPLEX library on macOS and Windows systems
804
805Testing
806-------
807
808- added parameter FILTER for tests/Makefile to run only tests with a specific pattern (ctest with -R FILTER)
809
810Miscellaneous
811-------------
812
813- adjusted Gurobi interface for Gurobi 12
814- reordered events: BESTSOLFOUND/NODE_FEASIBLE are now processed before the nodes are cut off and before NODE_DELETE events are processed
815- removed `#define` of `getcwd` (in case of Windows builds) in scip/def.h
816- the `#define` of `strcasecmp` and `strncasecmp` (in case of Windows builds) in scip/def.h will be removed with SCIP 10;
817 use `SCIPstr(n)casecmp()` (scip/pub_misc.h) instead
818
819@section RN911 SCIP 9.1.1
820*************************
821
822Fixed bugs
823----------
824
825- fix bug in separator aggregation that caused incorrect terminations when for an integral objective the objective limit was set to a fractional value
826- fix bug in memory management of doublelex matrices where indices were set beyond array bounds
827- store relevance flags in consdataTightenCoefs() of cons_linear.c to avoid dropping variables unintentionally due to numerical changes
828- fix possible segmentation fault when resetting local and global bounds of original variables after abnormal termination
829- compare coefficient scales to detect parallelism to avoid integral relaxations in detectRedundantConstraints() of cons_linear.c
830- remove coefficient information from linear constraint hashes in order to compare keys with tolerances
831- fixed NULL pointer dereference in SCIPtpiGetNumThreads() of TinyCThread interface if called before SCIPtpiInit(); now returns 0 in this case
832- calling SCIPsolveConcurrent() when SCIP was compiled without a TPI now results in a plugin-not-found error
833- fixed LPI status functions of lpi_cpx if the barrier is called
834- check cuts for redundancy after scaling in cutTightenCoefs() and cutTightenCoefsQuad() of cuts.c
835- maintain definition of artificial integral variables in xor constraints to avoid invalidation of conflict constraints
836- free childless nodes only after the deactivation of the old focus path in treeSwitchPath() of tree.c
837- only normalize rows for column norm evaluations in shift-and-propagate heuristic to avoid unscaled violations
838- expression handler for absolute value computes now also a cut when one of the bounds is infinite as long as the sign of the argument is known
839- check for more data to be freed before modifying nonlinear constraints in SCIPaddExprNonlinear()
840- allow for terms with zero coefficients when checking sum in SCIPexprCheckQuadratic()
841- do not abort writing of constraints to lp/pip files (and forget to free buffer memory) when encountering unsupported nonlinear constraint
842- fixed that strings with names and descriptions of the LPI's were not null-terminated
843- fixed decision on when to enforce nonlinear constraints on relaxation solutions if integer variables are present
844- fixed reading of very long lines (>78000 characters) in FlatZinc reader
845- fixed write of strings with at least 1024 characters when compiling with MSVS 2015 (14.0) or later (still an issue with earlier MSVS, which will not be fixed)
846- keep epsilon coefficients in applyFixings() of cons_linear.c until multiples are merged to avoid loss of relevant contributions
847- fixed that some variable type changes were not accounted correctly in presolve of linear constraints
848- fix constraint sorting in setpp-orbitope upgrade in symmetry code
849- fixed that SCIPnodeGetConsProps() also counted bound changes from propagators
850- use original and-constraints of an untransformed pseudoboolean constraint when copying original problems to avert segmentation faults
851- sort and-constraints of a pseudoboolean constraint with respect to the resultant problem indices to avoid shuffled copies
852- treat pseudoboolean constraints as nonlinear constraints in OPB reader to prevent duplication mistakes
853
854Examples and applications
855-------------------------
856
857- in example Binpacking implement Farkas pricing for packings because branching can actually lead to infeasible restricted master LPs
858
859Testing
860-------
861
862- allow unknown parameters to let tests pass if only optional dependencies are missing
863
864Build system
865------------
866
867### Cmake
868
869- fixed compilation and linking with HiGHS; to use HiGHS, cmake now requires to specify the directory containing the `highs-config.cmake` file via `-DHIGHS_DIR`
870- extended identification of Ipopt library on Windows to also look for ipopt.dll.lib, as this is used since Ipopt 3.13.0 (2019)
871
872
873@section RN910 SCIP 9.1.0
874*************************
875
876Features
877--------
878
879- added constraint handler that checks and enforces bounds on original variables which have been fixed or aggregated in the transformed problem
880- allow for implicit integer variables in xor constraints
881- implemented symmetry detection callbacks for pseudoboolean constraints
882- added option to consider enforcement of nonlinear constraints (including spatial branching) before integrality has been enforced
883
884Fixed bugs
885----------
886
887- make sure that, in dual proof analysis, upgraded constraints can report their number of variables
888- check knapsack constraints as linear constraints to avoid violations based on implicit integrality
889- make sure that symmetry detection callbacks report success
890- make arithmetics in cuts.c more robust to avoid invalid scg cuts due to numerical rounding sensitivity
891- allow to copy pseudoboolean constraints even if no AND constraints are present in order to avoid a warning
892- set value for variable that is introduced to reformulate nonlinear objective function when reading .nl files with initial solution
893- fixed that multi-aggregations from PaPILO were accepted without ensuring that their bounds hold
894
895Examples and applications
896-------------------------
897
898- TSP: removed `gzstream.h/hpp` and parse gzipped files differently
899
900Interface changes
901-----------------
902
903### New callbacks
904
905- SCIP_DECL_NLHDLRENFO takes additional parameter branchcandonly to indicate whether only branching candidates should be registered,
906 without looking for cuts or boundchanges
907
908### New API functions
909
910- new function SCIPgetExprActivityNonlinear() to get activity of nonlinear constraint
911- new function SCIPincludeConshdlrFixedvar() to include new constraint handler that checks bounds on fixed original variables
912
913### New parameters
914
915- limits/primal to terminate the solve as soon as the primal bound is at least as good as this value, same as limits/objectivestop (deprecated)
916- limits/dual to terminate the solve as soon as the dual bound is at least as good as this value
917- presolving/milp/internalmaxrounds to control the maximal rounds for each call of the milp presolver (PaPILO)
918- constraints/fixedvar/∗ to control the new constraint handler that checks bounds on fixed original variables
919- constraints/nonlinear/branching/mixfractional to specify minimal average pseudo cost count for discrete variables
920 at which to start considering spatial branching before branching on fractional integer variables
921 (default infinity means that integrality is always enforced before nonlinear constraints)
922- constraints/nonlinear/branching/fracweight to specify weight of fractionality of integer variables in spatial branching
923
924### New data structures
925
926- enum SCIP_Status has been extended by SCIP_STATUS_PRIMALLIMIT and SCIP_STATUS_DUALLIMIT to indicate termination at limits/primal and limits/dual respectively
927
928Build system
929------------
930- changed the default symmetry computation package from sassy+bliss to sassy+nauty
931- bliss source is no longer included in the source tree, but can be linked as external library (https://github.com/ds4dm/Bliss)
932- cmake now automatically downloads and installs the latest release version of SoPlex from GitHub if it is not found directly
933
934Miscellaneous
935-------------
936
937- updated nauty to version 2.8.8
938
939
940@section RN901 SCIP 9.0.1
941*************************
942
943Fixed bugs
944----------
945
946- fixed bug in detection of double lex matrices due to wrong memory allocation
947- fixed bug where parameter `limits/objectivestop` was copied to subscips in plugins which have different objectives
948- in count mode respect empty solution when problem is solved in presolving
949- fixed that SCIP may have tried to pass a negative random seed to an LP solver
950- fixed bug where conflict analysis in strong branching tried to analyze an unsuccessful LP solve
951- enable parameter limits/restarts by allowing to reach the restart limit in restartAllowed()
952- handle normalizing linear constraints in presolving with more caution to avoid numerical difficulties for integer variables with large coefficients
953- use quad precision to calculate residual activity bounds to reduce numerical errors for large variable bounds in cons_linear.c
954- in SCIPsolveProbingLP() when objective has been changed do not return cutoff due to exceeding the cutoff bound
955- set probing LP to be a relaxation only when objective has not been changed
956- declare contradicting infinities in getMinActivity() and getMaxActivity() as non-tight
957- reject farkas solution with large values to bound magnification of errors in SCIPgetFarkasProof()
958- if all variables are fixed, apply relative feasibility tolerance to avoid invalid infeasibility in applyFixings() of cons_linear.c
959- delete empty redundant knapsack and linear constraints after cleanup in SCIPmatrixCreate()
960- cleanup first constraints in SCIPcleanupConssVarbound(), SCIPcleanupConssSetppc(), and SCIPcleanupConssLogicor()
961- symmetry handling methods have not been added immediately after computing symmetries, which has been fixed
962- delay checking node limits after presolving to correctly continue up to the exceeding main node
963- simplified the objective sense assumption for the subproblems in the Lagromory separator
964- update effective root depth iteratively to avoid trapping it at a single child node
965- fixed that dualsparsify presolver did not always check do-not-multiaggregate variable flag
966- fixed bug in computing elements of orbits in orbital reduction
967
968Miscellaneous
969-------------
970
971- redefine isrelax to istight in cons_linear.c
972
973Build system
974------------
975
976### Cmake
977
978- A file cmake.log containing the changed options is written to the cmake build directory.
979- removed replacement of the settings of RelWithDebInfo
980- add compile option -ffp-contract=off or /fp:precise to enhance reproducibility across different systems
981
982### Makefile
983
984- add flags -ffp-contract=off and /fp:precise to enhance reproducibility across different systems
985
986Interface changes
987-----------------
988
989### New parameters
990
991- added parameter "propagating/symmetry/symtiming" to determine when symmetries are computed and handled
992
993### Changed parameters
994
995- Disabled "propagating/symmetry/addconsstiming" since it is not used anymore.
996- Disabled "propagating/symmetry/ofsymcomptiming" since it is not used anymore.
997
998@section RN900 SCIP 9.0.0
999*************************
1000
1001Features
1002--------
1003
1004- added simplification of abs(x)^n to x^n when n is even (simplify rule POW12)
1005- in expression simplification, added possibility to expand power of sum with exponents larger than 2 (simplify rule POW7)
1006- in expression simplification, added possibility to expand products with sums as factor when there are more than two factors (simplify rule SP12b)
1007- in expression simplification, added possibility to allow expanding power of products with fractional exponent (simplify rule POW5a)
1008- can now build with Lapack (used for solving nonlinear problems) explicitly; if IPOPT is used, then Lapack is accessed through it;
1009 an interface to Lapack is available in lapack_calls.h
1010- added support for logical constraints in binary variables and basic logical operators (and, or, not, equal) to AMPL .nl reader
1011- indicator constraints now use the same slack variable for the linear constraints if binary variables are used multiple times
1012 for indicator constraints
1013- new diving heuristic indicatordiving that focuses on indicator variables which control semicontinuous variables
1014- updated statistics on NLP relaxation; information on convexity of NLP has been added
1015- added new bandit method (EXP.3-IX) that is the new default of the ALNS heuristic
1016- added dialog to display recognized permutation symmetries ("display symmetry")
1017- The symmetry detection code has been completely restructured. Instead of completely encoding symmetry information in
1018 prop_symmetry.c, there is a new callback for constraint handlers, which returns symmetry relevant information by
1019 encoding a constraint as a node and edge colored graph. This way, also custom constraint handlers can provide
1020 symmetry information.
1021- added special presolving step for logicor and set covering/packing for constraints with two variables and one independent variable
1022- increased the depth field of the tree structure from 16 to 30 bits and the max depth of the search tree from 65534 to 1073741822
1023- added new cut selector plugin called cutsel_ensemble. Performs a superset of hybrid cutsel. Implements new filtering methods and scoring options.
1024- added new branching rule based on Gomory mixed-integer cuts
1025- added new branching score to the reliability pseudo-cost branching rule
1026- added new cut selector plugin called cutsel_dynamic. Performs a superset of hybrid cutsel. Implements new filtering methods and scoring options.
1027- added monoidal strengthening to intersection cut generation of nlhdlr_quadratic
1028- extended heuristic dps to run after processing the node and to use strict limits for the reoptimization step
1029- extended obbt propagator to handle variables of the linear constraints corresponding to indicator constraints
1030- added new heuristic heur_scheduler that models the selection of LNS and diving heuristics as a multi-armed bandit problem
1031- added nonlinear handler for signomial expressions: adds cuts based on a difference of convex functions representation
1032- Delayed separators are now called if no other cuts have been found. Previously, such separators were only called near stalling or when the separation rounds limit was reached.
1033- added a new separator sepa_lagromory to generate Lagromory cuts in a relax-and-cut framework, i.e., GMI cuts generated
1034 at different bases that are explored in the process of solving the Lagrangian dual problem at a node. This separator
1035 is OFF by default.
1036- when parsing nonlinear constraints from CIP files, the * after the number in a term is now optional if followed by a variable,
1037 i.e., instead of 3*<x>*<y>, now also 3<x>*<y> can be read, but 3<x><y> is not supported;
1038 this allows to read some CIP files that were written with SCIP < 8
1039- when running bliss, we now limit the number of actually created generators and not the ones considered by bliss
1040
1041Performance improvements
1042------------------------
1043
1044- Variable conflict-based addition of Schreier-Sims cuts for symmetry handling in prop_symmetry.c does no longer use
1045 an expensive explicit conflict graph construction.
1046- Only run propagation of indicator constraints if relevant variables have changed.
1047- Propagation of indicator constraints propagates maximal activity of linear constraint to upper bound of slack variable.
1048- Added initialization of LP relaxation for SOC constraints.
1049- Avoided some numerical issues when separating SOC constraints.
1050- If differentation of convex expression fails in convex nlhdlr, then a perturbed point is tried.
1051- Use sassy/bliss as default symmetry computation package.
1052- No longer linearize indicator constraints in undercover heuristic by default.
1053- Deactivate pre-root heuristic zeroobj in undercover heuristic.
1054- Added new branching score tiebreaker for reliability pseudo-cost branching rule
1055- Try nearest bound if zero solution value is out of bounds in heuristic trivial.
1056
1057Interface changes
1058-----------------
1059
1060### New and changed callbacks
1061
1062- Added solution linearization callback for nonlinear handlers.
1063 The nonlinear handler may use this callback to add tight cuts that use the given solution as reference point to the cutpool.
1064 The callback is called if option constraints/nonlinear/linearizeheursol is enabled.
1065- The callback for copying problem data SCIP_DECL_PROBCOPY() now has a parameter "original" indicating whether the original
1066 or transformed problem should be copied. Similarly, SCIPprobCopy() in prob.h/c has such a parameter.
1067- Added CONSGETPERMSYMGRAPH and CONSGETSIGNEDPERMSYMGRAPH callback for constraint handlers, which provides symmetry information about constraints to SCIP.
1068
1069### Deleted and changed API functions
1070
1071- SCIPtpiInitLock(), SCIPtpiDestroyLock(), SCIPtpiInitCondition(), SCIPtpiDestroyCondition() now take a double
1072 pointer to SCIP_LOCK/SCIP_CONDITION, respectively.
1073- Renamed SCIPtpiSumbitJob() to SCIPtpiSubmitJob().
1074- SCIPcreateConsIndicatorLinCons(), SCIPcreateConsIndicatorGenericLinCons() do not allow binvar to be NULL anymore
1075- Replaced SCIPnlrowSetCurvature() by SCIPsetNlRowCurvature().
1076- SCIPsnprintf() now returns the required string length in case reallocation is necessary.
1077- SCIPcomputeCoverUndercover() receives three more arguments which nonlinearities to cover
1078- removed definition of SQRT
1079- SCIPincludeObjConshdlr(), SCIPincludeConshdlr(), SCIPconshdlrCreate() receive two more arguments for the
1080 conshdlr callbacks CONSGETPERMSYMGRAPH and CONSGETSIGNEDPERMSYMGRAPH
1082- new parameter issigned for SCIPcomputeOrbitsSym()
1083- new parameter symtype for SCIPcomputeComponentsSym()
1084- new parameter symtype and permvardomaincenter for SCIPlexicographicReductionAddPermutation()
1085- replaced parameters matrixdata and exprdata of SYMcomputeSymmetryGenerators() by graph
1086
1087### New API functions
1088
1089- new functions for interfacing with Lapack: SCIPlapackIsAvailable(), SCIPlapackIsAvailable(), SCIPlapackComputeEigenvalues(), and SCIPlapackSolveLinearEquations
1090 These functions should be used instead of SCIPisIpoptAvailableIpopt(), SCIPcallLapackDsyevIpopt(), and
1091 SCIPsolveLinearEquationsIpopt() in the context of computing eigenvalues or solving linear equations.
1092 If IPOPT is available, the calls will be passed on to Ipopt's interface to Lapack.
1115- SCIPincludeCutselEnsemble(), SCIPselectCutsEnsemble() to include cutsel_ensemble or use the selection algorithm
1116- SCIPincludeBranchruleGomory() includes new gomory cut based branching rule
1117- SCIPgetVarAvgGMIScore(), SCIPincVarGMISumScore(), SCIPgetVarLastGMIScore(), SCIPsetVarLastGMIScore() set historical values used by SCIP's default branching rule
1118- SCIPincludeNlhdlrSignomial() includes the signomial nonlinear handler
1119- SCIPgetExprMonomialData() returns a monomial representation of a product expression
1120- SCIPestimateRoot() computes estimators for roots with exponent in [0,1]
1121- SCIPincludeCutselDynamic(), SCIPselectCutsDynamic() to include cutsel_dynamic or use the selection algorithm
1122- SCIPincludeSepaLagromory() to include the new Lagromory separator
1123- SCIPconsCompCheck() to compare two constraints based on their check priority
1124- SCIPgetConsPermsymGraph() and SCIPgetConsSignedPermsymGraph() to access the (signed) permutation symmetry detection graph of a constraint
1125- SCIPsetConshdlrGetPermsymGraph() and SCIPsetConshdlrGetSignedPermsymGraph() to set the (signed) permutation symmetry detection graph of a constraint
1126- SCIPconshdlrSupportsPermsymDetection() and SCIPconshdlrSupportsSignedPermsymDetection() to access whether a conshdlr supports detection of (signed) permutation symmetries
1127- new API functions for creating and manipulating a symmetry detection graph: SCIPcreateSymgraph(), SCIPfreeSymgraph(), SCIPcopySymgraph(), SCIPextendPermsymDetectionGraphLinear(),
1159 String values should not be quoted and spaces in string values are not supported.
1160- sassy can be used now as preprocessor for nauty/traces
1161- The solution status codes written to AMPL solution files now match those from https://mp.ampl.com/details.html#_CPPv4N2mp3sol6StatusE.
1162
1163### Changed parameters
1164
1165- change default value of parameter separating/filtercutpoolrel to FALSE
1166- Shrunk range of parameter "propagating/symmetry/sstleaderrule" from [0,3] to [0,2], removed "MAXCONFLICTS"-option.
1167- Removed reading/gmsreader/freeints. A default upper bound of +inf is now assumed for integer variables in GAMS (which is the case since GAMS 23.1).
1168- Disabled "propagating/symmetry/symfixnonbinaryvars" since it is not used in the new symmetry code.
1169- Replaced "propagating/symmetry/onlybinarysymmetry" with "propagating/symmetry/enforcecomputesymmetry" and set to FALSE by default.
1170- Disabled "propagating/symmetry/performpresolving" since running orbital reduction during presolving is not effective.
1171- Repurposed "propagating/symmetry/usedynamicprop" since it now also applies to lexicographic reduction.
1172- Changed default value of parameter "propagating/symmetry/addsymresacks" from FALSE to TRUE.
1173
1174### New parameters
1175
1176- separating/maxcutsgenfactor and separating/maxcutsrootgenfactor as factors (w.r.t. separating/maxcuts and
1177 separating/maxcutsroot) for limits on the number of cuts generated (which used to be constants '2')
1178- expr/pow/expandmaxexponent to specify limit on exponent when to expand power of sum
1179- expr/pow/distribfracexponent to enable expanding power of products with fractional exponents
1180- expr/product/expandalways to enable expanding any product with sums as factor (that is, also when more than two factors)
1181- nlhdlr/convex/maxperturb to specify maximal perturbation of non-differential reference points
1182- benders/default/nlpiterlimit to adjust iteration limit for NLP solver for Benders' decomposition NLP subproblems
1183- limits/objectivestop to interrupt the solve as soon as a primal solution is found
1184 that is at least as good as the given value
1185- heuristics/undercover/{coverand,coverind,covernl} to control which nonlinearities to consider (by default only "and" and nonlinear constraints)
1186- cutselection/ensemble/∗ all parameters for new ensemble cut selector
1187- cutselection/dynamic/∗ all parameters for new dynamic cut selector
1188- branching/relpscost/gmiavgeffweight specifies the weight in the relpscost branching score of the normalized efficacy of all generated GMI cuts (for a variable)
1189 branching/relpscost/gmilasteffweight specifies the weight in the elpscost branching score of the normalized efficacy of the last generated GMI cut (for a variable)
1190- nlhdlr/quadratic/usemonoidal to enable monoidal strengthening when separating quadratics with intersection cuts
1191- nlhdlr/quadratic/trackmore to collect more statistics for monoidal strengthening when separating quadratics with intersection cuts
1192- nlhdlr/quadratic/useminrep to use the minimal representation to compute cut coefficients when separating quadratics with intersection cuts
1193- nlhdlr/quadratic/sparsifycuts to enable sparsification of intersection cuts for quadratics
1194- heuristics/dps/reoptlimits to set strict limits for the reoptimization step in dps
1195- heuristics/dps/timing to run dps after processing the node
1196- heuristics/scheduler/∗ all parameters for new scheduler heuristic
1197- nlhdlr/signomial/enabled, nlhdlr/signomial/maxnundervars, nlhdlr/signomial/mincutscale: parameters for the signomial nonlinear handler
1198- separating/lagromory/freq to denote the frequency for calling Lagromory separator
1199- separating/lagromory/away to denote the minimal integrality violation of a basis variable to try separation
1200- separating/lagromory/dynamiccuts to denote whether the generated cuts be removed from LP if they are no longer tight
1201- separating/lagromory/maxroundsroot to denote the maximal number of separation rounds in the root node
1202- separating/lagromory/maxrounds to denote the maximal number of separation rounds in a non-root node
1203- separating/lagromory/nmaxcutsperlproot to denote, in the root node, the maximal number of Lagromory cuts that can be
1204 separated per explored basis of the Lagrangian dual
1205- separating/lagromory/nmaxcutsperlp to denote, in a non-root node, the maximal number of Lagromory cuts that can be
1206 separated per explored basis of the Lagrangian dual
1207- separating/lagromory/perroundnmaxlpiters to denote the maximal number of separating LP iterations that are allowed per
1208 separation round
1209- separating/lagromory/dualdegeneracyratethreshold to denote the minimum dual degeneracy rate for the separator execution
1210- separating/lagromory/varconsratiothreshold to denote the minimum variable-constraint ratio on the optimal face for the
1211 separator execution
1212- many other advanced parameters for the Lagromory separator, which are also mentioned under separating/lagromory/∗
1213
1214### Data structures
1215
1216- new data structure SYM_GRAPH to encode symmetry information from a constraint
1217- new data structure SYM_EXPRDATA to encode symmetry information from expressions
1218- replaced enum SYM_SYMTYPE by a complete new one; removed SYM_RHSSENSE, added SYM_NODETYPE and SYM_CONSOPTYPE
1219
1220Deleted files
1221-------------
1222
1223- deleted the now unused files: tpi_none.h, tpi_openmp.h, tpi_tnycthrd.h, type_tpi_none.h, type_tpi_openmp.h, type_tpi_tnycthrd.h
1224
1225Unit tests
1226----------
1227
1228- new unittests for nlhdlr_quadratic that test monoidal strengthening and the use of the minimal representation to compute cut coefficients
1229- unittests for nlhdlr_signomial
1230
1231Testing
1232-------
1233
1234- changed `set lim obj` to `set lim objective` in ctest since `obj` is no longer unambiguous
1235
1236Build system
1237------------
1238
1239### Cmake
1240
1241- New flag -DLAPACK=on for linking with Lapack (must be available in the system)
1242- added flag option "SYM=sbliss" for using sassy/bliss as a graph automorphism package
1243- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP.
1244- added flag option "SYM=snauty" for using sassy/nauty as a graph automorphism package
1245
1246### Makefile
1247
1248- added flag option "nauty" for SYM variable to specify which graph automorphism package should be used
1249- added flag option "sbliss" (sassy/bliss) for SYM variable to specify which graph automorphism package should be used
1250- added flag option "snauty" (sassy/nauty) for SYM variable to specify which graph automorphism package should be used
1251- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP
1252- New flag LAPACK for linking with Lapack (must be available in the system)
1253- A file scip/config.h is created in the build directory ($(OBJDIR)/include) now.
1254 Defining NO_CONFIG_HEADER is no longer necessary and has no effect anymore.
1255
1256Fixed bugs
1257----------
1258
1259- Number of runs in which separation is enabled will now be correct as per "separating/maxruns" parameter. Earlier,
1260 separation was enabled for "maxruns + 1" number of runs, i.e., separation was enabled even when "maxruns = 0" was set.
1261- add safeguard for number of selected cuts
1262- use double double precision for delta in activity updates of cons_linear.c
1263- sort constraints in checkSolOrig() to keep the logic of constraint handlers intact
1264- fixed make install when SHARED=no and make uninstall
1265- check absolute coefficients relative to extremal average to avoid invalid unifications in normalizeCons()
1266- enforce and check symmetry-based constraints to take their locks (in dual reductions) into account
1267- flush changes at the end of SCIPlpiSetBase() in lpi_grb.c to apply the newly set basis correctly
1268
1269Miscellaneous
1270-------------
1271
1272- The TPI has been changed to become mostly independent from the actual parallel interface during compile time.
1273 For this, the locks and conditions are now pointers to abstract structs.
1274- fixed that scip/def.h, the header for C preprocessor definition (`#define`'s), included headers for some SCIP type and function definitions
1286- fixed that scaling of rows in Gurobi interface (SCIPlpiScaleRow()) changed infinite sides to large finite ones (1e20) when scale factor is negative
1287- check whether objective limit is truly reached in SCIPlpiIsStable()
1288- if an objective limit is set and Mosek claims that it is exceeded, check that this is indeed the case in SCIPlpiIsStable()
1289- the .mps file reader was extended to additionally accept .mps files with the objective sense section on one line
1290- ensure that delayed cutpool separation does not happen if enough cuts have been found already
1291- fixed that a Gurobi or Mosek interface (LPI) could not be freed from a thread different than the one it was created in, which lead to problems when, e.g., using the concurrent optimizer
1292- in cons_varbound if both variables are fixed, instead of propagating the constraint check the feasibility of the constraint since propagating can lead to unnecessary numerical troubles
1293- fixed memory leak in branching rule "distribution"
1294- fixed that undercover did not enforce that sufficiently many variables in an and-constraints were fixed to have it linearized in the generated sub-scip
1295- fixed two bugs in cons_varbound: avoid adding variable bounds if vbdcoef is infinite and unlock/lock variables if lhs/rhs/vbdcoef are changed
1296- globalize constraint changes before bound changes during the effective root shift in treeSwitchPath() to correctly update variable locks by avoiding global bounds with outstanding bound change events when deleting constraints
1297- fixed error when attempting to copy SCIP with activated pricers
1298- remove integrality check for implicit integral variables in cons_integral.c, updated the definition for variable type implicit integer to be more explicit that these variables can take fractional values, and updated FAQ entry
1299- updated and, or, and pseudoboolean constraint handlers to better handle fractional implicit integer variables in enforcement
1300- avoid invalid strong Chvatal-Gomory cuts by ceiling with tolerance in the calculation of parameter k and flooring slack coefficients with standard epsilon tolerance as well as quad precision
1301- add missing row links to columns in SCIPflushRowExtensions() required to maintain correct row norms
1302- restrict separator intobj to solutions for which there can be no better feasible integral objective values to avoid cutting them off
1303- delay removal of clique lists from SCIPvarRemoveCliquesImplicsVbs() into cliqueCleanup() to avoid segmentation faults by incomplete cleanups after variable conversions
1304- reject sub-solutions with invalid objectives in SCIPtranslateSubSols() due to contradicting infinite contributions
1305- correct column index in getMinMaxActivityResiduals() to make presolver dualinfer work
1306- copy quiet flag from main scip's message handler to the one of solverscip in concurrent optimization
1307- avoid bound tightening cycles towards huge redundancy bounds in fullDualPresolve() to avert fatal numerical trouble in representing vertices of linear relaxations with unbounded domains
1308- fix problem where debug solution did not work if branching constraints are present
1309- update index of dominating variable on coefficient deletion in dualPresolving() of constraint handler logicor
1310- pass on flags from a redundant to the implying varbound constraint in preprocessConstraintPairs() to avoid suboptimal fixings by model relaxations
1311- apply reductions of dualinfer only if a dual solution exists (primal is bounded)
1312- before presolving is finished check solutions before retransforming them including tiny values to keep check flags consistent
1313- disable heuristics before and during presolving in benders decomposition to avoid messing up the objective structure in the solution store by dropping auxiliary variables in the required retransformations
1314- correct local flag of singleton conflict constraints in tightenSingleVar() against invalid bound globalization
1315- respect unboundedness in the computation of activity bounds in conflict.c to avoid invalid huge bounds due to small coefficients on unbounded variables
1316- ensure positive sides of a linear constraint when recognizing a set partition in rangedRowSimplify() to account for redundancy issues
1317- relax numerical conditions for variable aggregations to avert invalid variable fixings
1318- fixed harmless read of uninitialized data when creating parameters
1319- fix call of SCIPnlpiOraclePrintProblem in nlpi_worhp
1320
1321Performance improvements
1322------------------------
1323
1324- Use sassy/bliss as default symmetry computation package.
1325
1326Interface changes
1327-----------------
1328
1329### Interfaces to external software
1330
1331- added interface to nauty/traces for symmetry computation
1332- added interface to sassy, a preprocessor for symmetry computation
1333- The directory src/sassy contains the source code of sassy.
1334
1335Build system
1336------------
1337
1338### Cmake
1339
1340- added flag option "SYM=sbliss" for using sassy/bliss as a graph automorphism package
1341
1342### Makefile
1343
1344- added flag option "nauty" for SYM variable to specify which graph automorphism package should be used
1345- added flag option "sbliss" for SYM variable to specify which graph automorphism package should be used
1346- use SYM=sbliss by default, since sassy and bliss are now shipped with SCIP
1347
1348Miscellaneous
1349-------------
1350
1351- the parameter change callback is no longer called at the moment a parameter is created
1352
1353@section RN804 SCIP 8.0.4
1354*************************
1355
1356Features
1357--------
1358
1359- use quad precision in cutsSubstituteMIR() for substituting slack variables into CMIR cuts
1360- use quad precision for activity computations in cons_linear.c
1361
1362### Deleted and changed API functions
1363
1364- SCIPshrinkDisjunctiveVarSet() no longer attempts to cutoff the current node if it finds the
1365 given disjunction to be infeasible; it is now in the responsibility of the caller to act accordingly
1366
1367### New API functions
1368
1369- added SCIPskipSpace
1370- added XML parser routines from src/xml/xml.h
1371
1372### Interfaces to external software
1373
1374- updated XPRESS interface to work with XPRESS 41 as well
1375- new interface to LP solver HiGHS (lpi_highs.cpp)
1376
1377### Changed parameters
1378
1379- changed integer parameter "propagating/symmetry/recomputrestart" from range {0, 1, 2} to being fixed at value 0
1380
1381Unit tests
1382----------
1383
1384- added new checks for objective, bounds and sides inside the scaling tests in lpi/change.c
1385
1386Fixed bugs
1387----------
1388
1389- relax condition of assert in lpSolve to hold only if lp/checkstability is true
1390- OPB reader: dynamically increase the size of the line buffer for reading in getMaxAndConsDim()
1391- Enabled the solution limit checks in SCIPsolveIsStopped in solve.c when in SCIP_STAGE_PRESOLVING
1392- fix quad precision comparison for the calculation of knapsackcover constraints.
1393- force copying of symmetry constraints for concurrent solve
1394- increase the precision of double multiplications in quad precision environments
1395- corrected handling of different variable types in symmetry
1396- orbitope detection: refine computation of overlap structure and fixed bug in finding orbitope generators
1397- ensure that winner is always determined in concurrent mode
1398- when a row with invalid index range is added to the global cutpool, update the indices instead of failing with an assert
1399- update of watched literals in cons_xor.c and ensure that fixed variables are counted in propacateCons()
1400- avoid some numerical issue in check for redundant variables in linear constraints (introduced with version 8.0.2)
1401- more rows are treated as being integral in cutsSubstituteMIR() for CMIR cuts
1402- fixed several relaxations of the rhs of cuts to 0 in cuts.c
1403- avoid aggregation into a single linear constraint if they should not be upgraded (needed for indicator constraints)
1404- apply effective root changes before fork is repropagated during treeSwitchPath() in tree.c
1405- avoid invalid objective value for solutions generated from an unbounded LP relaxation in case of a nonlinear objective function
1406- disable recomputing symmetries after a restart (constraint removal is not permitted)
1407- avoid cutting off optimal solutions for small feasibility tolerances in conflict analysis
1408- initialize variable in presol_dualsparsify.c
1409- fix in presolving of variable bound constraints to use absolute instead of relative difference
1410- free variable histories in reoptimization mode
1411- handle whitespaces in interactive shell history consistently
1412- check and enforce equalities on which the objective is projected in cons_linear.c
1413- ensure row feasibilities of solution shiftings in heur_oneopt.c and heur_twoopt.c
1500- new parameters to turn on more statistics: misc/showdivingstats (diving heuristics), heuristics/alns/shownbstats (ALNS), estimation/showstats (tree size estimation)
1501
1502### Data structures
1503
1504- added nrootcalls and ncutsadded to SCIP_Cutpool
1505- added fromcutpool flag to SCIP_Row and fixed 33 bit allocation
1656 Removed support for parameterized expressions.
1657- Added support for expression types sin, cos, and entropy. Added an expression type that stores a SCIP variable.
1658- Added handling of sin and cos expressions in OSiL reader.
1659- Added handling of sin, cos, and tan expressions in ZIMPL reader.
1660- Added expression handler plugin type, removed user expression type.
1661- Replaced expressions, expression trees, and expression graphs by a new implementation of expressions.
1662- Added differentiation methods (Gradients and Hessian directions) to expressions.
1663- Added integrality information to expressions.
1664- Added comparison and hashing of expressions.
1665- Improved simplification of expressions and identification of common subexpressions, in particular terms that appear
1666 equally in several quadratic functions are now identified.
1667- Expression simplification now expands powers also when the resulting exponents will be larger than 2.
1668- Added table to print statistics on expression handlers.
1669- Removed interval-arithmetic evaluation from expression interpreter (interfaces to automatic differentiation codes).
1670- Hessians for user-provided expression handlers are not available in the NLP solver interfaces for now.
1671- Sparse Hessians are now returned by expression interpreter. Removed dense Hessians.
1672
1673Constraint handlers for NLP:
1674- cons_nonlinear has been completely rewritten and now handles constraints of the form lhs <= expr <= rhs, where
1675 expr is an expression using the new expression type. A linear part of a nonlinear constraint is no longer distinguished.
1676- Methods that work on a particular nonlinear structure are now implemented via nonlinear handlers (nlhdlr).
1677 These handlers are plugins of cons_nonlinear and interact with cons_nonlinear by detecting structures in expressions and
1678 providing propagation and separation mechanisms.
1679- Added nlhdlr "default" as a mandatory nlhdlr: this is a nlhdlr that gets active on expressions that no other nlhdlr handles.
1680 It then uses the callbacks implemented in expression handlers to provide domain propagation and linear under/overestimates.
1681- Added nlhdlr for quadratic expressions: domain propagation that was previously part of cons_quadratic; separation via intersection cuts (currently disabled).
1682- Added nlhdlr for bilinear expressions: collects bilinear products and provides under/overestimation of a product over a 2D-projection of the LP.
1683- Added nlhdlr for convex and concave expressions: detection of convex/concave subexpressions and linear under/overestimation.
1684- Added nlhdlr for quotients: detects quotients, provides specialized linear under/overestimation and domain propagation for univariate quotients.
1685- Added nlhdlr for perspective reformulations: detects expressions in semi-continuous variables and tightens linear
1686 under/overestimates of these expressions by applying a perspective transformation.
1687- Added nlhdlr for second-order cones: detects second-order cone constraints (as ||x|| <= t or a quadratic that can written like that) and
1688 separates on a disaggregated reformulation (similar to cons_soc previously).
1689- Removed constraint handlers abspower, bivariate, quadratic, and soc.
1690- Removed simplification of duplicate abspower constraints for now.
1691 Removed simplification of abspower constraints with loose variables.
1692 Removed resolving of domain propagation (ConsResProp callback) and conflict analysis for abspower constraints.
1693 Removed propagation of varbounds for variables of abspower constraints.
1694 Removed reformulation of abs(x)^p * x into signpower expression for now.
1695- Removed reformulation of SOC constraints when adding to the NLP.
1696 Removed possibility to add linearizations a la Glineur or BenTal&Nemirovski for SOC constraints.
1697- Removed possibility to disaggregate quadratic constraints.
1698 Removed lifted tangent inequalities for bilinear terms in quadratic constraints.
1699 Removed option to project LP solution onto feasible region of a quadratic constraint via interior point or gauge function.
1700 Removed handling of unbounded LPs when enforcing quadratic constraints.
1701- Removed construction of cuts from interval gradients for nonlinear constraints.
1702 Removed possibility to pretend that all nonlinear constraints are convex.
1703 Removed possibility to create local or non-initial nonlinear constraints for now.
1704- Removed explicit reformulation of nonlinear constraints in presolve.
1705 An extended formulation is now generated implicitly and used to construct the LP relaxation,
1706 but the original formulation is used to check feasibility, propagate variable domains, etc.
1707 Variables that are added for the extended formulation are now marked as relaxation-only.
1708- Improved locking of nonlinear variables in nonlinear constraints by taking monotonicity into account.
1709- Improved mechanisms to detect and handle structures in nonlinear constraints, which allows for several algorithms
1710 to work simultaneously on equal or overlapping expressions.
1711- Improved linearization of (sums of) products of binary variables, e.g., clique information is now taken into account.
1712 Removed option to linearize products between a binary and a non-binary variable.
1713- Nonlinear constraints with the same function (but possibly different left- or right-hand-side) are now merged.
1714- When a variable appears in only one concave less-or-equal constraint, it will be fixed to one of its bounds in more cases now.
1715- New branching rule for variables in nonlinear constraints (implemented in cons_nonlinear) that scores candidates
1716 based on constraint violation, variable type, and pseudo-costs simultaneously.
1717- Added tables to print statistics of nonlinear constraint handler and nonlinear handlers.
1718
1719Performance improvements
1720------------------------
1721
1722- Use the objective cutoff row as base row for separation in sepa_aggregation.c.
1723- Separate lifted cover cuts based on newer lifting function of Letchford and Souli (2019) in sepa_aggregation.c.
1724- In-tree restarts due to tree size estimation have been made compatible with orbital fixing.
1725- Improved upgrade of orbisacks to packing/partitioning orbitopes.
1726- Improved running time of symresack cover separation.
1727- Improved propagation algorithm for orbisack and symresack.
1728- Improved handling for expressions of type signpower in CppAD interface by making use of CppADs conditional expressions.
1729- Faster reevaluation of Hessian for quadratic expressions in CppAD interface.
1730- Enabled optimization of taped expressions in the CppAD interface.
1731- Sparse Hessian evaluation for expressions with sparse Hessian in the CppAD interface.
1732- Disabled branching on variables that are added for the extended formulation of a nonlinear constraint.
1733- Prefer branching on variables in nonconvex terms of nonlinear constraints also if a cut could be generated but would yield a small reduction in the convexification gap only.
1734- When violations of nonlinear constraints are tiny, the feasibility tolerance for the LP relaxation may now be reduced temporarily to allow for cuts to have an effect.
1735- Improved under/overestimation of multidimensional vertex-polyhedral (e.g., multilinear or concave) functions by use of scaling and keeping the cut-generating LP around.
1736- Products in nonlinear constraints are no longer disaggregated for the extended formulation.
1737- No longer relax bounds of integral variables when computing bounds on activity in nonlinear constraints.
1738- Revised and improved Ipopt interface.
1739- Revised and improved subNLP primal heuristic, in particular choice of iteration limit and starting condition and reuse of subSCIP.
1740- Merge strongcg into the gomory separator to avoid computing the same base equality twice. The files
1741 sepa_strongcg.{h|c} have been removed.
1742- The RENS neighborhood in ALNS now fixes fractional variables if necessary for reaching its target fixing rate.
1743- Use cpsolver emphasis in sepa_rapidlearning.
1744- If decomposition/maxgraphedge = 0, the computation of the block graph is completely turned off.
1745- Fixed a performance bug in cons_integral.c where rounding information was passed incorrectly to the generic diving algorithm.
1746
1747Examples and applications
1748-------------------------
1749
1750- Add c++ Sudoku example
1751- Removed circle.c and renamed string.c to spring.c in CallableLibrary example.
1752- SCIP-Jack (Steiner tree application):
1753 Most files have been modified and many new ones have been added (code base more than doubled).
1754 Two new problem classes are supported: maximum-weight connected subgraph problem with budget constraints, partial-terminal node-weighted Steiner tree problem.
1755 Major performance improvements accross all problem classes that are supported.
1756
1757Interface changes
1758-----------------
1759
1760### New and changed callbacks
1761
1762- extend SEPAEXEC{LP,SOL} callbacks by parameter "depth", which should be used within separation instead of SCIPgetCurrentDepth()
1763- extend SCIPseparateSolCutpool() by parameter "pretendroot", which is passed to SCIPcutpoolSeparate() instead of SCIPtreeGetCurrentDepth(scip->tree) == 0
1781- added SCIP_NLPIPROBLEM* problem to SCIP_DECL_NLPIGETSOLVERPOINTER
1782
1783### Deleted and changed API functions
1784
1785- When calling SCIPdelVar() in the SCIP_STAGE_PROBLEM stage, it is now documented as the user's responsibility to ensure
1786 the variable is not present in any constraints. Otherwise, SCIPsolve() now returns SCIP_INVALIDDATA.
1787- removed SCIPselectCuts(), replaced by SCIPselectCutsHybrid() of the hybrid cut selector plugin
1788- If SCIPvarMarkRelaxationOnly() is called for a variable, then this now need to happen before the
1789 variable is added to the transformed problem (SCIPaddVar()).
1790 SCIPvarMarkRelaxationOnly() will automatically call SCIPvarMarkDeletable().
1791- SCIPcomputeOrbitsFilterSym() and SCIPcomputeComponentsSym(): Type of argument componentblocked
1792 changed from SCIP_Shortbool* to unsigned*.
1793- removed SCIPsetParam()
1794- SCIPcreateConsOrbitope() and SCIPcreateConsBasicOrbitope() have two new arguments "usedynamicprop"
1795 and "mayinteract" to encode whether a dynamic reordering of the orbitope rows shall be used in
1796 full orbitope propagation and whether the orbitope might interact with other symmetry handling
1797 methods, respectively.
1798- internal function SCIPgetPropertiesPerm() has been replaced by SCIPisInvolutionPerm()
1799- internal function SCIPgenerateOrbitopeVarsMatrix() has new arguments "storelexorder", "lexorder",
1800 "nvarsorder", "maxnvarsorder" to compute and store the lexicographic order defined by an orbitope
1801- renamed SCIPcomputeArraysIntersection() and SCIPcomputeArraysSetminus() to
1802 SCIPcomputeArraysIntersectionInt() and SCIPcomputeArraysSetminusInt(), respectively, and changed
1803 their return type from SCIP_RETCODE (which _always_ was SCIP_OKAY) to void
1804- removed SCIPincludeDialogDefault(), use SCIPincludeDialogDefaultBasic() instead and check whether you also need SCIPincludeDialogDefaultSet() and SCIPincludeDialogDefaultFix()
1805- removed exprint argument from SCIPaddNlRowGradientBenderscutOpt()
1806- added copyexprhdlrs argument to SCIPcopyPlugins() (19th position)
1807- added copycutselectors argument to SCIPcopyPlugins() (10th position)
1808- removed refpoint argument from SCIPaddSquareSecant()
1809- added argument exprdata to SYMcomputeSymmetryGenerators()
1824- renamed SCIPsetNlRowExprtree() to SCIPsetNlRowExpr() and changed type of expr(tree) argument to SCIP_EXPR*
1825- SCIPenableNLP() is no longer allowed in stages INITSOLVE and SOLVING
1826- removed SCIPaddLinearConsToNlpHeurSubNlp()
1827- SCIPhasNLPSolution() now returns true also if a infeasible solution to the NLP exists; SCIPcreateNLPSol() can now also be used when only an infeasible solution to the NLP exists
1828- renamed SCIPsolveNLP() to SCIPsolveNLPParam() and added parameter SCIP_NLPPARAM param
1829- removed SCIPsolveDiveNLP(), use SCIPsolveNLPParam() instead
1877- removed SCIPnlpiOracleGetVarDegree() and SCIPnlpiOracleGetVarDegrees(), use SCIPnlpiOracleIsVarNonlinear() and SCIPnlpiOracleGetVarCounts(), respectively, instead
1878- removed SCIPnlpiOracleGetConstraintDegree(), use SCIPnlpiOracleIsConstraintNonlinear() instead
1879- removed argument messagehdlr from SCIPnlpiOraclePrintProblem() and SCIPnlpiOraclePrintProblemGams()
1880- removed SCIPcreateNlpiProb(), use SCIPcreateNlpiProblemFromNlRows() instead
1881- renamed SCIPupdateNlpiProb() to SCIPupdateNlpiProblem() and moved into scip_nlpi.{h,c}
1882- renamed SCIPaddNlpiProbRows() to SCIPaddNlpiProblemRows() and moved into scip_nlpi.{h,c}
1884- removed SCIPgetIpoptApplicationPointerIpopt(), use SCIPgetNlpiSolverPointer() instead
1885- removed SCIPnlpStatisticsCreate(), SCIPnlpStatisticsFree(), SCIPnlpStatisticsGetNIterations(), SCIPnlpStatisticsGetTotalTime(), SCIPnlpStatisticsSetNIterations(), SCIPnlpStatisticsSetTotalTime(), the struct is public now
1886- renamed LapackDsyev() to SCIPcallLapackDsyevIpopt()
1887- renamed SCIPsolveLinearProb() to SCIPsolveLinearEquationsIpopt()
1888
1889Expression interpreter:
1890- removed functions that operated with SCIPInterval
1891- changed first argument of SCIPexprintCreate() to SCIP*
1892- added SCIP* as first argument to SCIPexprintFree()
1893- added SCIP* as first argument to SCIPexprintCompile(), changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA**
1894- added arguments SCIP*, SCIP_EXPRINT*, and SCIP_EXPR* as first arguments to SCIPexprintFreeData()
1895- renamed SCIPexprintGetExprtreeCapability() to SCIPexprintGetExprCapability();
1896 added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
1897- removed SCIPexprintNewParametrization()
1898- SCIPexprintEval(): added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
1899- removed SCIPexprintEvalInt()
1900- SCIPexprintGrad(): added SCIP* as first argument, changed third argument to SCIP_EXPR*, added fourth argument SCIP_EXPRINTDATA*
1901- removed SCIPexprintGradInt()
1902- removed SCIPexprintHessianSparsityDense() and SCIPexprintHessianDense, use SCIPexprintHessianSparsity() and SCIPexprintHessian() instead
1903
1904Expressions:
1905- removed SCIPexpropGetName(), use SCIPexprhdlrGetName() instead
1906- removed SCIPexpropGetNChildren()
1907- removed SCIPexprGetOperator(), use SCIPexprGetHdlr() instead
1908- removed SCIPexprGetOpIndex(), SCIPexprGetOpReal(), SCIPexprGetOpData(), use SCIPexprGetData() instead
1909- removed SCIPexprGetRealPowerExponent(), SCIPexprGetIntPowerExponent(), SCIPexprGetSignPowerExponent(), use SCIPgetExponentExprPow() instead
1910- removed SCIPexprGetLinearCoefs(), SCIPexprGetLinearConstant(), use SCIPgetCoefsExprSum() and SCIPgetConstantExprSum() instead
2030- renamed SCIPgetNAllBilinearTermsQuadratic() to SCIPgetNBilinTermsNonlinear() and changed argument from SCIP* to SCIP_CONSHDLR*
2031- renamed SCIPgetAllBilinearTermsQuadratic() to SCIPgetBilinTermsNonlinear() and replaced arguments by SCIP_CONSHDLR* and changed return type to SCIP_CONSNONLINEAR_BILINTERM*
2032- removed SCIPaddBilinearIneqQuadratic(), use SCIPinsertBilinearTermImplicitNonlinear() instead
2033- renamed SCIPcreateConsQuadratic() to SCIPcreateConsQuadraticNonlinear() and removed argument stickingatnode
2034- removed SCIPincludeConshdlrSOC()
2035- replaced SCIPcreateConsBasicSOC() by SCIPcreateConsBasicSOCNonlinear()
2036- deprecated SCIPcreateConsSOC(), use SCIPcreateConsBasicSOCNonlinear() instead
2037- deprecated SCIPgetNlRowSOC(), use SCIPgetNlRowNonlinear() instead
2257- Removed parameters for strongcg separator: separating/strongcg/..., i.e.,
2258 maxrounds, maxroundsroot, maxsepacutsroot, maxsepacuts, dynamiccuts. One can control the
2259 strongcg behavior throught the parameters of sepa_gomory.
2260- renamed separating/{minortho,minorthoroot,objparalfac,intsupportfac} to cutselection/hybrid/{minortho,minorthoroot,objparalweight,intsupportweight}
2261
2262### New parameters
2263
2264- It is now possible to add orbitope constraints to handle symmetries even if not all variables
2265 in a component of the symmetry group are binary. This feature can be enabled using the
2324- new parameters "branching/inference/conflictprio" and "branching/inference/cutoffprio" that allow
2325 using the different score criteria in inference branching hierarchically
2326- new parameters "heuristics/alns/nodesquotmin", "heuristics/alns/maxcallssamesol" and "heuristics/alns/initduringroot"
2327 to control neighborhoods in ALNS
2328- new parameter "benders/default/benderscut/optimality/mir" to control whether mixed-integer rounding procedure is applied to Benders optimality cuts
2329- new parameter "misc/avoidmemout" to try to avoid running into memory limit
2445- added test projection:transitivity in prob/obbt.c
2446- added reader/nl.c
2447- added test intervalarith:sincos in scip/intervalarith.c
2448- added sepa/minor.c
2449- added sepa/rlt/cuts.c
2450- added sepa/rlt/product_detection.c
2451- added sepa/rlt/separation.c
2452- added tests test_compute_symmetry:expr{1,2,3,4} in symmetry/compute.c
2453
2454Build system
2455------------
2456
2457- the separate NLPI library has been integrated into the main SCIP library;
2458 uses of NLPILIBFILE or NLPILIBSRC in Makefiles that use make/make.project
2459 should be removed
2460
2461### Cmake
2462
2463- replace flag PARASCIP by THREADSAFE
2464- option AMPL is now ON by default
2465- add -D_XOPEN_SOURCE=600 cflag for compilation on systems other than windows
2466- add compile options directly instead of modifying CMAKE_C_FLAGS and CMAKE_CXX_FLAGS
2467
2468### Makefile
2469
2470- prefix PKG_CONFIG_PATH with Ipopt's pkgconfig dir instead of postfixing
2471- replace flag PARASCIP by THREADSAFE
2472- flag AMPL is now true by default
2473- libscip has been renamed to libscipbase and libscipsolver has been renamed to libscip
2474 in order to have the same library names for makefiles and cmake. For downward
2475 compatibility libscipsolver still exists (as a link).
2476
2477Fixed bugs
2478----------
2479
2480- fixed handling of multi-aggregation in cons_symresack and cons_orbisack
2481- SCIPgetLowerbound() now consistently returns infinity when status is infeasible
2482- improved the likelihood that a solution that satisfies the nonlinear constraints in the transformed (presolved) problem is also feasible for the original problem
2483- worked around a problem with derivatives of pow at 0 with non-integer exponents in CppAD
2484- fixed that setting of feasiblity and optimiality tolerance for NLP relaxation was overwritten with defaults when solving NLP
2485- fixed variance computation in t-value computation in hypothesis testing of reliability branching
2486- fixed potential overflow in cuts.c:evaluateLiftingFunctionKnapsack()
2487- do not transfer dual reductions to main SCIP in sepa_rapidlearning if strong dual reductions are forbidden
2488- fixed a bug in cons_setppc.c:removeDoubleAndSingletonsAndPerformDualpresolve() which led to wrong variable aggregations
2489- added missing redundancy check to coefficient tightening routine in cons_varbound that led to wrong variable locks
2490- added a check of numerics to avoid wrong reductions in cons_linear.c:simplifyInequalities()
2491- fixed a bug in cons_logicor.c regarding fixed variables that were not removed
2492- presol_milp.c handles variable fixings, suggested by PaPILO, more carefully to cover all cases that can appear
2493- fixed several reproducability bugs that led to different solving paths across multiple runs with one SCIP environment
2494- fixed check of limits/absgap, which was incorrectly applied to the scaled objective of the transformed problem
2495
2496Miscellaneous
2497-------------
2498
2499- in LP, use absolute instead of relative tolerances to check whether solutions from LP solver are primal feasible
2500- when a restart occurs, SCIP now asserts (during EXITSOLVE) that all relaxation-only variables are unlocked and
2501 only captured by the transformed problem.
2502- Avoid redundant calls to LP solver when LP is already flushed and solved
2503- In SCIPdebugMsg(), SCIPsetDebugMsg(), SCIPstatDebugMsg() strip directory from filename.
2504- Recompute activity of rows when checking LP solutions instead of trusting the value given by the LP solver
2505- The define NPARASCIP has been replaced by SCIP_THREADSAFE
2506- Parameters are not reset to their default values before activating an emphasis setting; this now allows to combine
2507 different emphasis settings.
2508- If a lazy bound is set to a value that is tighter than the current global bound, then the global bound is now tightened accordingly.
2509
2510@page RN7 Release notes for SCIP 7
2511
2512@section RN703 SCIP 7.0.3
2513*************************
2514
2515Interface changes
2516-----------------
2517
2518### New API functions
2519
2520- added function SCIPwithDebugSol() to determine whether SCIP was compiled with WITH_DEBUG_SOLUTION
2521
2522- New function SCIPcreateConsBounddisjunctionRedundant() and SCIPcreateConsBasicBounddisjunctionRedundant() that allow
2523 the input to contain redundant literals.
2524
2525### Changed API functions
2526
2527- added __attribute__((format(printf,,,))) to variadic SCIP message printing functions;
2528 this enables warnings about mismatches between format string and variadic function arguments if using GCC.
2529
2530### Interfaces to external software
2531
2532- removed MATLAB interface from interfaces/matlab
2533
2534Build system
2535------------
2536
2537- Compilation will now also work in a raw tarball of the scip git repository
2538
2539### Cmake
2540
2541- Make find_package more verbose and require packages to be found. Now enabled packages that are not found result in an error.
2542
2543Fixed bugs
2544----------
2545
2546- Fixed numerical bug by creating and checking the empty solution when problem vanishes in presolving.
2547- Fixed several bugs in reoptimization.
2548- Fixed bug in cons_bounddisjunction in which a constraint leads to a cutoff.
2549- Fixed bug in reoptimization by avoiding redundant literals for bound disjunctions.
2550- Replace wrong usage of CMAKE_BINARY_DIR by PROJECT_BINARY_DIR in CMake system
2551- Fixed lpi_glop to use absl flag instead of GFlags
2552- Fixed invalid initialization of limits/softtime parameter in cons_components
2553- Fixed MIN macro not defined in some cases.
2554- Safeguard some API functions for querying solving statistics against segmentation faults after SCIPpresolve()
2555- Fixed unfreed solution in concurrent solving
2556- Make sure that logicor constraints are enforced/separated if genlogicor is true in cons_indicator.
2557 Thus, do not change constraints/logicor/sepafreq anymore, but output warning.
2558- Fixed assert that assumed infeasibility cannot occur in presol_boundshift.
2559- Fixed sign bug during creation of conflict constraints with almost zero left-hand side.
2560- Disabled call of conflict handler for conflict sets that contain relaxation-only variables.
2561- Fixed bug in cons_symresack by initializing all constraint data in constrans
2562- Avoid allowing the upgrade of linear constraints corresponding to indicators in propagation of nodes.
2563- Fixed bug in computing lex. min/max faces in dynamic orbitope propagation.
2564- Limit vbounds propagator to one sweep through all bounds per call in order to avoid an infinite loop.
2565- Fixed mismatches between formatter strings and arguments in calls to SCIP message printing functions.
2566
2567Miscellaneous
2568-------------
2569
2570- To avoid performance variablity during reoptimization, the active constraints are now stored in the same order as in the
2571 original problem.
2572- Added workaround for bug in MSVS 2019 when compiling CppAD source.
2573- The original order of variables is now only restored after presolve if `randomization/permutevars` is set to FALSE.
2574
2575@section RN702 SCIP 7.0.2
2576*************************
2577
2578Features
2579--------
2580
2581- Extended check for valid variable and constraint names in PIP writer.
2582- Indicator constraints now write the name of the linear constraint in CIP format. This avoids a complicated
2583 name matching during parsing. The old format is still supported.
2584- The objective scale and offset are now taken into account when reading/writing problems in lp/mps/fzn/pip format.
2585 This often changes the behavior when writing transformed problems.
2586
2587Performance improvements
2588------------------------
2589
2590Examples and applications
2591-------------------------
2592
2593- Add c++ Sudoku example
2594
2595Interface changes
2596-----------------
2597
2598### Deleted and changed API functions
2599
2600- deprecated SCIPsetParam(); use SCIPsetIntParam(), SCIPsetRealParam(), etc, instead
2601
2602### New API functions
2603
2604- new function SCIPcolGetVarProbindex() for accessing the probindex of a variable corresponding to a column
2605- added new sorting functions SCIPsortPtrRealRealBoolBool()
2606
2607Fixed bugs
2608----------
2609
2610- Fixed a sign bug occuring for some cases in the computation of the directed cutoff distance
2611- Fixed overflow in inference information of cumulative constraint handler
2612- Fixed problem with propfreq == 0 in cons_linear.c
2613- Fixed aggregation heuristic in sepa_aggregation.c to not use local rows when that is requested nor modifiable rows
2614- Fixed problem with incompatibility of symmetry handling in Benders decomposition
2615- Fixed parsing of small number in CIP format of nonlinear constraint
2616- Fixed problem in upgrading full orbitopes to partitioning orbitopes
2617- Fixed treatment of negated variables in parsing orbitope constraints
2618- Fixed potential indexing error in prop_vbounds.c
2619- Fixed bug in writing fzn format
2620- Revert to old parameter value when parameter change is rejected in PARAMCHGD callback
2621- Fixed order of linker flags when building AMPL interface with cmake system.
2622- Fixed bug with ofsymcomptiming == 0: now symmetry is actually computed
2623- Improved separation for SOC constraint with multiaggregated variable on right-hand-side.
2624- Fixed bug in presol_boundshift: do not shift non-active variables
2625- Fixed bug in domain propagation for SOC constraints with negative coefficient for variable on right-hand-side.
2626- Fixed bug with multi-aggregated integer variables in cons_xor.
2627- Fixed bug with changed number of variables in storing relaxation solution in probing/diving.
2628- Fixed issues with scip statistics
2629- Fixed issue with multi-aggregated variables
2630- Fixed issue in with buffer memory in cons_cumulative
2631
2632@section RN701 SCIP 7.0.1
2633*************************
2634
2635Build system
2636------------
2637
2638### Cmake
2639
2640- Fixed cmake module for Ipopt to support Ipopt 3.13
2641- Added cmake variable BLISS_LIBRARY_DIR to pass a bliss library
2642- Added warning to require minimal GCC version 4.8
2643- Renamed FindCriterion cmake findmodule to FindCRITERION
2644
2645### Makefile
2646
2647- Updated make/make.project for macOS
2648- Add SANITZERFLAGS (only OPT=dbg) to LDFLAGS also if SHARED=true (and rename SANITZERFLAGS to SANITIZERFLAGS)
2649- Fixed GCC version check in make/make.linux.gnu.dbg
2650
2651Fixed bugs
2652----------
2653
2654- Fixed handling of constant term in quadratic objective of pip-reader
2655- Fixed incorrect value string for parameter estimation/completiontype
2656- Fixed initialization of first LP which led to wrong output about LPs not resolved correctly
2657- Fixed bug in SCIPcutpoolClear() function not clearing internal datastructures properly
2658- Fixed inability to set a value in a solution if it was within epsilon to the current value
2659- Fixed problems for linking optimized code with debug library of SCIP (and vice versa) by moving debug-only members
2660 to end of SCIP structs
2661
2662Miscellaneous
2663-------------
2664
2665- Variables that are marked as relaxation-only are no longer checked against debug solutions if
2666 they are captured by the transformed problem only.
2667
2668@section RN700 SCIP 7.0.0
2669*************************
2670
2671Features
2672--------
2673
2674- Using the parameter "propagating/symmetry/recomputerestart" one can now decide to recompute symmetries after a
2675 restart or not. Previously one could just turn off symmetry computation after a restart. If orbital fixing
2676 has found a reduction before the restart occurred, symmetries have to be updated to ensure correctness.
2677 To this end, the user can decide via "propagating/symmetry/disableofrestart" whether orbital fixing is disabled or
2678 whether symmetries are recomputed.
2679
2680- extended relaxators statistics in solve statistics about information on number of cutoffs, improved bounds, etc.
2681
2682- extends SMPS file reader for the stochastic information, the sto files, to read a lower bound for the discrete
2683 scenarios. The lower bound is used when creating the auxiliary variables for Benders' decomposition.
2684
2685- extended Benders framework to solve NLPs and generate optimality and feasibility cuts from their solution
2686 when the subproblem is convex nonlinear.
2687
2688- extended Benders framework to create copies of Benders decompositions that can be used in a multithreading environment
2689
2690- additional functionality has been added to enable the transfer of Benders' decomposition cuts between different SCIP
2691 instances, e.g., when used in UG
2692
2693- LP rows (SCIP_ROW) can now store pointer to a constraint from which the row originates
2694
2695- Trust region, a new LNS heuristic, has been added to SCIP as both a standalone primal heuristic heur_trustregion.c
2696 and as a neighborhood inside of Adaptive Large Neighborhood Search (heur_alns.c). This heuristic is designed to improve the
2697 heuristic performance of the Benders' decomposition algorithm. It builds upon the successful trust region approaches
2698 applied to Benders' decomposition.
2699
2700- Modularity of symmetry handling has been increased. It is now possible to use orbitopes (i.e., polyhedral symmetry
2701 handling techniques) and orbital fixing on the same instance.
2702
2703- cut strengthening enabled within the Benders' decomposition framework. This uses a mix of the Improved Magnanti-Wong
2704 method and Kelly's method. The cut strengthening is enabled by setting the paramemter
2705 "benders/<bendersname>/cutstrengthenenabled" to TRUE. The parameters "cutstrengthenmult", "noimprovelimit" and
2706 "corepointperturb" control the behavior of the cut strengthening method. Additionally, the parameter
2707 "cutstrengthenintpoint" allows the user to specify the solution that is used to initialize the core point. The options
2708 are the first LP solution, the first integer feasible solution, a relative interior point, a solution vector of all
2709 ones and a solution vector of all zeros. Also, the core point can be reinitialized after each update to the incumbent
2710 solution.
2711
2712- added option to adjust weights of different scores in relpscost (hybrid) branching rule based on degeneracy information
2713 and skip strong branching for very high degeneracy rates
2714
2715- added new SCIP_DECOMP* object to store user decompositions. The user can specify one or several decompositions by assigning variable
2716 and/or constraint labels either through the API or by reading a file in DEC format (which is one of the formats that GCG writes).
2717 This format specifies constraint labels, variable labels are inferred from that. The decomposition is transformed after presolving.
2718- statistics regarding the number of blocks, the largest and smallest blocks, the border, and the constraint graph are printed for the original decomposition,
2719 and for each decomposition after presolving.
2720- the decomposition can be used as initial decomposition for the Benders functionality of SCIP.
2721- new subsection "How to provide a problem decomposition" in the SCIP documentation
2722
2723- GINS heuristic can make use of a user-provided decomposition labels in two ways:
2724 1. by selecting a block of variables that maximizes the potential, and randomly selecting a start variable for the neighborhood and/or
2725 2. by selecting an interval of consecutive blocks as neighborhood, until fixing rate is reached. In this case, no variable is randomly selected.
2726
2727- extend potential parameter of GINS to allow computation based on local LP solution, as well
2728
2729- new primal heuristic Adaptive Diving, which registers all publicly available dive sets from other diving heuristics.
2730 At each call, it selects one of the available dive sets based on the user's score type choice (heuristics/adaptivediving/scoretype).
2731 During the solution process, the heuristics learns online which divesets reach the best score, and executes them more frequently.
2732 The statistic output for Diving heuristics has been extended to incorporate the statistics of each dive set within Adaptive diving.
2733
2734- Added new penalty alternating direction method (PADM) primal heuristic that splits the problem into several sub-SCIPs
2735 according to a user-provided decomposition. The sub-SCIPs are solved on an alternating basis until a feasible solution of
2736 the original problem is found.
2737
2738- Symmetry handling constraints (cons_orbisack, cons_orbitope, cons_symresack) now have an additional parameter to encode
2739 whether they are model constraints, i.e., define the problem, or whether they are only present to handle symmetries.
2740
2741- The symmetry code has been completely restructured. The presolvers presol_symbreak and presol_symmetry as well as the propagator
2742 prop_orbitalfixing have been merged into the single propagator prop_symmetry to avoid storing the same information
2743 multiple times. This propagator is now responsible for adding symmetry handling constraints as well as activating orbital
2744 fixing. Moreover, the new file symmetry.c contains general functions for symmetry computations like orbit computations.
2745
2746- Variables can now be marked as "relaxation-only". This flag should be used to introduce new variables that are required
2747 to define a relaxation, but that are not part of any checked constraints. Essentially, these variables should only be used
2748 in the current SCIP solve and disregarded after a restart or in SCIP copies. Hence, these variables are not copied by SCIPcopy and
2749 SCIPgetVarCopy, they are currently not used in conflict constraints, and cuts involving them are not upgraded to linear constraints.
2750 Relaxation-only variables cannot appear in the objective function.
2751
2752- The OSiL reader now supports nonlinear expressions of type "signpower".
2753
2754- Expressions of form abs(x)^p * x in a nonlinear constraint are now sometimes recognized and handled by abspower constraints.
2755
2756- If polyhedral symmetry handling methods are used (cons_orbisack, cons_orbitope, cons_symresack), it is now possible to
2757 recompute symmetries if a restart occurred.
2758
2759- upgrade some more quadratic constraints to second-order cone constraints, that is,
2760 handle linear binary variables as if squared in simple upgrade and
2761 do not require bounds for variables that have a zero entry in the computed eigenvectors in the non-simple upgrade
2762
2763- new variable event when changing the variable type
2764
2765- It is no longer necessary to provide a SCIP pointer for the subproblem in SCIPaddBendersSubproblem if custom solving
2766 methods are defined. A NULL pointer can be supplied to SCIPaddBendersSubproblem. In this case, no internal Benders'
2767 cut generation methods can be used.
2768
2769- Using the parameter "constraints/symresack/checkmonotonicity" one can now decide to upgrade to packing/partitioning
2770 symresacks even if the underlying permutation is not monotone.
2771
2772- New branching rule `vanillafullstrong`, mostly for scientific purpose, with the following features:
2773 1) no cutoff or domain reduction: only branching;
2774 2) idempotent (optional): leave SCIP, as much as possible, in the same state before / after the strong branching calls
2775 - basically, do not update any statistic;
2776 3) donotbranch (optional): do no perform branching. So that the brancher can be called as an oracle only
2777 (on which variable would you branch ? But do not branch please);
2778 4) scoreall (optional): keep scoring variables, even if infeasibility is detected;
2779 5) collectscores (optional): store the candidate scores from the last call, which can then be retrieved by calling SCIPgetVanillafullstrongData();
2780 6) integralcands (optional): consider integral candidates for branching,
2781 i.e., get candidates from SCIPgetPseudoBranchCands() instead of SCIPgetLPBranchCands().
2782
2783- If a reference value (misc/referencevalue) is given, the primal-reference and reference-dual integrals are calculated automatically and printed within the SCIP statistics.
2784
2785- Locally valid cuts / rows are now considered for dual proof analysis when `conflict/uselocalrows` is set to TRUE.
2786
2787- Linking variables in the linking constraint handler (cons_linking.{ch}) can now be integer or continuous. The coefficients of the binary variables are therefore now stored as SCIP_Real.
2788
2789- To save memory, it is now possible to remove all variables from the internal symmetry data structures that are
2790 not affected by any symmetry.
2791
2792- Allow to filter first variables from orbits and transfer pseudo cost information to variables in orbit
2793
2794- Add integration of external MILP presolve library as a SCIP presolver plugin that runs on MILP problems
2795
2796- Parallelisation can be used when applying Benders' decomposition. There are two different forms of parallelisation
2797 available. The first is applying Benders' decomposition within a parallel branch-and-bound. This is achieved through
2798 the integration with the UG framework. The second is the use of shared memory parallelisation for solving the Benders'
2799 decomposition subproblems. A priority queue has been added to help with load balancing.
2800
2801- The Benders' decomposition framework can handle MINLPs. If a convex relaxation of the MINLP exists, then this is
2802 solved to generate optimality and feasibility cuts. The extensions to the framework are:
2803 - New generic solving methods to solve convex NLP subproblems.
2804 - Modification to benderscut_opt and benderscut_feas to enable the generation of cuts from convex NLPs.
2805 - Addition of benderscut_feasalt to generate feasibility cuts from an alternative subproblem that minimises the
2806 violation of infeasible problems.
2807 - Better handling of subproblem solution results
2808
2809- Adds a feasibility phase to the Benders' decomposition subproblem solving methods. The feasibility phase adds slack
2810 variables to each of the constraints to ensure feasibility of the subproblem. A large coefficient is given to these
2811 slack variables in the objective function to penalise constraint violations. The coefficients are progressively
2812 increased until all slack variables take the value 0.0.
2813
2814- Improved convexity check for Benders' decomposition subproblems. The constraints of the subproblem are now checked for
2815 convexity in the initialisation of the Benders' decomposition algorithm. This enables the solving of convex NLPs as
2816 Benders' decomposition subproblems.
2817
2818- Benders' decomposition can be applied using decomposition supplied in the DEC format. To apply Benders' decomposition
2819 the parameters decomposition/benderslabels and decomposition/applybenders must be set to TRUE.
2820
2821- new event handler event_estim.c/h that approximates search tree completion and estimates tree size
2822 to trigger restarts; many approximations of search tree completion and estimation, including WBE, SSG, and tree profile method
2823- new display column that reports approx. search tree completion during the search, and an overview in the statistics table
2824- added resources (script, tutorial, test data) to adapt tree size estimation to user instances.
2825
2826- Orbital Fixing uses a list of variables that have been fixed globally since the computation of symmetries to filter
2827 symmetries. Previously, some plugins were disabled, which is not necessary anymore.
2828
2829- A new presolver "dualsparsify" was added. It tries to combine columns (i.e. variables) to cancel nonzero coefficients in the constraint matrix.
2830
2831- The presolver "tworowbnd" was implemented with better performance.
2832
2833- To be able to calculate better bounds for the dual variables, the presolver "dualinfer" was extended by the ability to perform convex combinations of continuous columns.
2834
2835- allow disabling of pricers during solving process
2836
2837- added emphasis setting for numerically challenging instances
2838
2839Performance improvements
2840------------------------
2841
2842- Extended cut presolving by removing variables that been fixed at their bounds
2843
2844- Improved branching point selection when branching on externals branching candidates. Instead of using exactly the
2845 LP solution, a point closer to the middle of the variables domain is chosen.
2846
2847- Matrix presolvers that do not work on incomplete matrices now skip matrix creation if unsupported constraint types are detected.
2848
2849- consLockBenders callback implemented to add down locks on the Benders' decomposition auxiliary variables and
2850 up and down locks per subproblem for all master problem variables. This allows the use of presolving and propagation
2851 with Benders' decomposition.
2852
2853- improved performance of orbital fixing in several ways:
2854 store permutations in transposed form to improve cache efficency;
2855 reverse order to speed up filtering of permutations;
2856 handle variables globally fixed to 1 in list;
2857 use event handler to catch global fixings;
2858 speed up orbit computations;
2859 change handling of restarts;
2860 use only permutations that can contribute to a variable's orbit;
2861
2862- allow rapid learning at local nodes
2863
2864- allow to recompute cut without using fractional values for sepa_cgmip
2865
2866- restrict the number of the clique table nonzeros relative to the number of problem nonzeros, which could be a performance bottleneck.
2867
2868- variable fixings of LP face heuristic are now computed earlier; subproblem creation is skipped if not enough variables are fixed.
2869
2870- Improved domcol presolver to not require a complete representation of all constraints in the matrix
2871
2872- performance improvement of adaptive large neighborhood search heuristic on merely continuous problems. The heuristic
2873 stops if presolving in the sub-SCIP fixes less than 50 % of the current target fixing rate over all variables
2874 (including continuous).
2875
2876- reduce memory usage in symmetry detection by a staggered allocation with decreasing overhead for larger instances
2877
2878- improved full orbitope propagation using a static implementation or a dynamic reordering of orbitope rows by a global rank function
2879
2880- improved detection of packing/partitioning orbitopes
2881
2882- enable an in-tree restart if after a reasonable initialization, the estimated size of the remaining tree is large.
2883
2884
2885Examples and applications
2886-------------------------
2887
2888- added functions to set and get hmin and hmax for optcumulative constraints
2889
2890Interface changes
2891-----------------
2892
2893### New and changed callbacks
2894
2895- new optional callback `SCIP_DECL_DIVESETAVAILABLE` to check preconditions for this dive set, e.g., if an incumbent solution is available,
2896 which is passed as new argument to SCIPcreateDiveset(). SCIPcreateDiveset() has another new parameter "ispublic".
2897
2898- new callback `SCIP_DECL_CONSHDLRCOPY` and `SCIP_DECL_CONSCOPY` in cons_orbisack and cons_symresack
2899
2900- new `idempotent` argument to SCIPgetVarStrongbranchInt() and SCIPgetVarStrongbranchFrac(),
2901 so that statistics are not updated during the call. Likewise, new `updatecol` and `updatestat` arguments to SCIPcolGetStrongbranch().
2902
2903- callback `SCIP_DECL_CONSHDLRENFOLP` can now also return SCIP_SOLVELP as *result, which indicates to the SCIP core that the LP relaxation
2904 should be solved again because the primal feasibility tolerance of the LP has been tightened (using SCIPsetLPFeastol())
2905
2906- extension of SCIP_PQUEUE by a new callback SCIP_DECL_PQUEUEELEMCHGPOS to catch swaps as well as functionality to delete arbitrary elements from the priority queue.
2907
2908### Deleted and changed API functions
2909
2910- LPI:
2911 + now for all lp interfaces consistent requirements on SCIP_LPPAR:
2912 LPITLIM and BARRIERCONVTOL positive or zero; FEASTOL, DUALFEASTOL, LPTILIM strictly positive
2913 + now projecting SCIP_LPPAR values on feasible values for each lp interface
2914 + add interface to Glop
2915 + fixed mapping between scaling parameter values in Gurobi LPI lpi_grb
2916- Symmetry:
2917 + removed function SCIPseparateCoversOrbisack() in cons_orbisack.h since the orbitope constraint
2918 handler has its own implementation of this routine with advanced features now
2919 + renamed SCIPgetGeneratorsSymmetry() to SCIPgetSymmetry() and removed two arguments
2920 + extended function SCIPgetSymmetry(): It is possible to access both the original and
2921 transposed permutations matrix as well as the (independent symmetry) components of a permutation group now.
2922 + arguments of functions SCIPcreateConsOrbisack(), SCIPcreateConsBasicOrbisack(), SCIPcreateConsOrbitope(),
2923 SCIPcreateConsBasicOrbitope(), SCIPcreateConsSymresack(), SCIPcreateConsBasicSymresack(), and SCIPcreateSymbreakCons() extended
2924 by "ismodelcons" to encode whether the constraints are model constraints or not
2925 + the function SCIPgetSymmetry() no longer accepts the parameter recompute, but has parameter permvarmap as new input
2929 + add function SCIPcomputeOrbitsComponentsSym() to compute orbits without filtering permutations and indices of orbits for each variable
2930- SCIPallowObjProp() and SCIPallowDualReds() are deprecated and replaced by SCIPallowWeakDualReds() and SCIPallowStrongDualReds(), respectively
2931- Benders' decomposition
2932 + changed SCIPstoreBenderscutCut() in scip_benders.c to SCIPstoreBendersCut(). Where this function used to take a
2933 SCIP_BENDERSCUT pointer, it now accepts a SCIP_BENDERS pointer.
2934 + the functions SCIPsolveBendersSubproblem() no longer accepts the parameter type. The type is not a necessary
2935 argument for the subproblem solving method.
2936 + arguments of functions SCIPbendersSolveSubproblemLP(), SCIPbendersSolveSubproblemCIP(), and SCIPbendersOnlyCheckConvexRelax() changed
2937 - removed SCIPbenderscutGetNAddedCuts() and SCIPbenderscutGetAddedCutData()
2938
2939
2940### New API functions
2941
2942- new argument "onlyifcomplete" in SCIPmatrixCreate() to skip matrix creation right after detecting unsupported constraint types
2943 and new arguments to count statistics when doing a clean-up of inactive variables in the constraints before building the matrix
2944
2945- new argument "threadsafe" in SCIPcopy(), SCIPcopyConsCompression(), SCIPcopyOrig(), SCIPcopyOrigConsCompression and
2946 SCIPcopyBenders(). This argument must only be set to TRUE if the source and target SCIP instances are to be solved in
2947 parallel. Setting this argument to TRUE has a performance cost.
2948
2949- new argument "append" in SCIPsetModifiedDefaultSettingsIpopt()
2950- functions SCIPclearRelaxSolVals(), SCIPsetRelaxSolVal(), SCIPsetRelaxSolVals(), SCIPsetRelaxSolValsSol(), and SCIPmarkRelaxSolValid()
2951 receive an additional argument "relax" to store the relaxation handler as creator of the relaxation solution.
2952
2953- LP:
2954 - SCIProwGetOriginCons() now returns a SCIP_CONS* instead of a SCIP_CONSHDLR*, use SCIProwGetOriginConshdlr() for the previous behavior
2955 - SCIPcreateRowCons() and SCIPcreateEmptyRowCons() now expect a SCIP_CONS* instead of a SCIP_CONSHDLR*,
2956 use SCIPcreateRowConshdlr() and SCIPcreateEmptyRowConshdlr(), respectively, for the previous behavior
2957 - deprecated SCIPlpfeastol() and SCIPchgLpfeastol(), use SCIPgetLPFeastol() and SCIPsetLPFeastol()
2958
2959- new parameter "divecontext" for every function that queries statistics for a diveset. The context can be used to distinguish between the dive set
2960 as single (standalone) heuristic or within Adaptive Diving.
2961- new parameters "divecontext" and "iterlim" to SCIPperformGenericDivingAlgorithm() to control in which context (single,adaptive) statistics are updated.
2962
2963- SCIPcopyVars, SCIPcopy, SCIPcopyConsCompression, and SCIPgetVarCopy do not copy variables that are marked as relaxation-only,
2964 thus it cannot be assumed anymore that each active variable from the master SCIP also has a counterpart in the copy.
2965 SCIPcopy, SCIPcopyConsCompression, and SCIPcopyConss can now return *valid=TRUE if some non-checked and non-enforced constraints were not copied, e.g.,
2966 because they involved relaxation-only variables. Thus, a copy is already regarded as valid if all checked or enforced constraints were copied successfully.
2967
2968- linking constraint handler:
2969 - changed type of vals argument from int* to SCIP_Real* in SCIPcreateConsLinking() and SCIPcreateConsBasicLinking()
2970 - SCIPgetIntvarLinking() has been renamed to SCIPgetLinkvarLinking().
2971 - changed return value of SCIPgetValsLinking() from int* to SCIP_Real*.
2972 - new function SCIPgetBinvarsDataLinking().
2973
2974- SCIPbendersCheckSubproblemOptimality() now returns a boolean indicating whether the subproblem is optimal or not.
2975 Previously this result was returned through a parameter. The change was required to facilitate the integration with
2976 the UG framework.
2977
2978- deleted SCIPcombineTwoInt(), SCIPcombineThreeInt(), SCIPcombineFourInt(); use the appropriate SCIPhashTwo(), ..., SCIPhashSeven() function instead
2979
2980- SCIPsetupBendersSubproblem takes a parameter of the enforcement type.
2981
2982- SCIPcreateNlpiProb takes a hashmap to store the map between the nlrows and the index in the nlrow array.
2983
2984### New API functions
2985
2986- SCIPallowWeakDualReds() and SCIPallowStrongDualReds() replace the deprecated SCIPallowObjProp() and SCIPallowDualReds(), respectively
2987- functions have been added to facilitate the transfer of Benders' decomposition cuts between solvers in UG. These include
2988 SCIPapplyBendersStoredCuts(), SCIPbendersGetNStoredCuts(), SCIPbendersGetStoredCutData() and
2989 SCIPbendersGetStoredCutOrigData().
2990- added SCIPisConvexAbspower()
2991- new functions SCIPsolGetType(), SCIPsolGetRelax(), SCIPsolSetRelax(), SCIPsolSetLPRelaxation(), SCIPsolSetStrongbranch(),
2992 SCIPsolSetPseudo to set or query the new type attribute of a primal solution. The type attribute gives information
2993 about the origin of the solution, ie, whether it was created by a relaxation handler,
2994 by the LP relaxation, by strong branching, by the current pseudo solution, or by a primal heuristic.
2995 The meaning of the argument 'heur' in all creation methods for primal solutions such as SCIPcreateSol() stays unchanged.
2997- new API functions SCIPsetCommonSubscipParams(), SCIPtranslateSubSol(), and SCIPtranslateSubSols() shared by several Large Neighborhood Search heuristics.
2998- new API function SCIPgetLPDualDegeneracy() to get two measures for the dual degeneracy of the current LP
2999- new API functions SCIPdivesetIsAvailable() to check preconditions of a dive set and SCIPdivesetIsPublic() to check if the dive set can be used
3000 by other primal heuristics.
3001- new API functions SCIPcomputeOrbitsSym(), SCIPcomputeOrbitsFilterSym(), SCIPgetPropertiesPerm(), SCIPdetermineBinvarAffectedSym(),
3002 SCIPdetermineNVarsAffectedSym(), SCIPcomputeComponentsSym(), and SCIPextendSubOrbitope(), SCIPgenerateOrbitopeVarsMatrix() for symmetry computations
3003- new API functions SCIPvarIsRelaxationOnly() and SCIPvarMarkRelaxationOnly() to query and set, resp., whether a variable is marked as relaxation-only
3004- new API functions SCIPconshdlrGetNUpdateConss() and SCIPconshdlrGetUpdateConss(), for expert users only
3005- new API function SCIPgetNConflictDualproofsApplied()
3006- new API functions SCIPeventGetOldtype() and SCIPeventGetNewtype() for the new event when changing the variable type
3007- new API function SCIPisConvexConsQuadratic() to check whether a quadratic constraint is convex when a given set of variables would be fixed
3008- new API functions SCIPgetLPFeastol(), SCIPsetLPFeastol(), and SCIPresetLPFeastol() to get, set, and reset (to the default), respectively, the primal
3009 feasibility tolerance for the LP relaxation
3010- new API functions SCIPcleanupConss{Linear,Varbound,Setppc,Logicor,Knapsack}() to clean up inactive variables from those types of linear constraints
3011- new API function SCIPsetBendersSubproblemComp() used to add a custom comparison method for ordering the Benders'
3012 decomposition subproblem solves. The comparison method is used to help with load balancing.
3013- new API function SCIPgetRowObjParallelism to get the objective parallelism of a row
3014- new API function SCIPcolGetAge to get the age of a column
3015- added SCIPhashThree(), SCIPhashFive(), SCIPhashSix(), and SCIPhashSeven() that complement SCIPhashTwo(), SCIPhashFour() to combine 32bit integers to
3016 a 32bit hash value
3017- new API function SCIPgenerateAndApplyBendersOptCut is used to generate a Benders' optimality cut using the dual
3018 solutions. This function can be supplied vectors for the primal and dual solution for generating an optimality cut.
3019 This avoids the need for a SCIP instance to solve the Benders' decomposition subproblem and generating cuts.
3020- new API function SCIPconsAddCoef used for adding a coefficient to a linear-type constraint.
3021- new API functions SCIPconsNonlinearGetRhs, SCIPconsNonlinearGetLhs and SCIPconsNonlinearAddLinearCoef for getting the
3022 RHS and LHS from a nonlinear-type constraint and adding a linear coefficient to the constraint.
3023- new API function SCIPbendersSolSlackVarsActive for checking whether any slack variables from the feasibility phase are
3024 active in the subproblem solution.
3025- new API functions SCIPbendersSetSubproblemType and SCIPbendersGetSubproblemType sets and gets the subproblem type.
3026 This is either:
3027 - Convex constraints with continuous variables
3028 - Convex constraints with discrete variables
3029 - Non-convex constraints with continuous variables
3030 - Non-convex constraints with discrete variables
3031- new API functions SCIPbendersSetSubproblemIsNonlinear() and SCIPbendersSubproblemIsNonlinear() for setting and
3032 identifying whether the Benders' decomposition subproblems contain nonlinear constraints. Similarly, the functions
3033 SCIPbendersSetMasterIsNonlinear() and SCIPbendersMasterIsNonlinear() sets and identifies whether the Benders'
3034 decomposition master problem contains nonlinear constraints.
3035- new API function SCIPapplyBendersDecomposition for applying Benders' decomposition given a decomposition in the DEC
3036 format
3037- new API function SCIPwasNodeLastBranchParent to query if a node has been the parent of the most recent branching in the tree
3038- new API functions SCIPtreemodelInit(), SCIPtreemodelFree(), SCIPtreemodelIsEnabled(), SCIPtreemodelSelectCandidate() related to the new
3039 treemodel way of comparing branching candidates. These functions are only currently used for reliability pscost branching, but they can be used
3040 in other parts of the code.
3041- New function SCIPcalcChildEstimateIncrease() to compute the increase in the child estimation
3042- new API functions SCIPisOrbitalfixingEnabled() and SCIPgetSymmetryNGenerators() to check whether orbital fixing is
3043 enabled and to get the number of generators of the current symmetry group, respectively
3044- new API function SCIPdelNlRow() to remove a row from the NLP
3045
3046### Event system
3047
3048- new event type SCIP_EVENTTYPE_NODEDELETE to react on nodes that are about to be deleted from the tree
3049
3050### Changed parameters
3051
3052- renamed parameter "propagating/orbitalfixing/enableafterrestart" to ".../symmetry/recomputerestart"
3053- Parameter "misc/allowdualreds" is now called "misc/allowstrongdualreds"
3054- Parameter "misc/allowobjprop" is now called "misc/allowweakdualreds"
3055- changed default values of propagation (new value: 1, old value: 5) and separation frequency (new value: -1, old value: 5) in cons_orbitope.c
3056- all primal heuristics that use sub-SCIPs are disabled within the heuristics fast emphasis setting
3057- deleted parameter heuristics/localbranching/useuct, use heuristics/useuctsubscip instead
3058- changed default value of "presolving/symbreak/detectorbitopes" (new value: TRUE, old value: FALSE)
3059- extended range of "misc/usesymmetry" (new range: [0,3], old range: [0,2])
3074- changed default value of "heuristics/coefdiving/freq" (old: 10, new: -1)
3075- changed default value of "heuristics/conflictdiving/freq" (old: -1, new: 10)
3076- changed default value of "heuristics/conflictdiving/lockweight" (old: 1.0, new: 0.75)
3077- replaced parameter "numerics/lpfeastol" by "numerics/lpfeastolfactor" to specify which factor should be applied to the SCIP feasibility
3078 tolerance to initialize the primal feasibility tolerance of the LP solver
3079- enabling aggressive presolving now activates all available presolving plugins,
3080 and decreases the presolving/restartfac parameter correctly with respect to default.
3081- changed default value of heuristics/rins/nodesquot to 0.3 (was 0.1), to compensate
3082 the removal of a hard coded factor of 3.0 in the code without affecting the default behavior
3083 of the RINS heuristic.
3084- changed default value of "constraints/quadratic/empathy4and" (old: 0, new: 2)
3085- changed default value of "propagating/redcost/useimplics" (old: TRUE, new: FALSE)
3086
3087### New parameters
3088
3089- the possibility to define the Benders' decomposition auxiliary variables as implicit integer is provided. This
3090 behavior is controlled with an additional parameter in the Benders' decomposition framework.
3091- added parameter benders/<bendersname>/cutcheck to enable the generation of Benders' decomposition cuts during solution
3092 checking.
3093- constraints/orbitope/usedynamicprop: the possibility to propagate orbitope constraints by reordering the rows based on the
3094 branching strategy is provided (only possible for non-model constraints)
3095
3096- new parameters heuristics/shiftandpropagate/minfixingratelp and heuristics/locks/minfixingratelp to stop the
3097 heuristics after propagating integer fixings if no sufficient fixing of the all variables (including continuous)
3098 could be achieved. These parameters help to avoid solving LP's that are comparable in hardness to the main root LP.
3099
3100- Added parameters branching/midpull and branching/midpullreldomtrig to control by how much to move
3101 the branching point for an external branching candidate closer to the middle of the candidates domain. The
3102 default of 0.75 and 0.5, respectively, uses a point that is 75*alpha% closer to the middle of the domain, where
3103 alpha is the relative width of the candidates domain (width of local domain divided by width of global domain),
3104 if the latter is below 0.5, and alpha=1.0 otherwise. That is, with the default settings, a branching point is
3105 chosen closer to the middle of the candidates domain if the variables local domain is still similar to its
3106 global domain, but is chosen closer to the LP solution if the local domain is much smaller than the global
3107 domain.
3108
3109- Added parameter lp/minmarkowitz to set the Markowitz stability threshold (range 0.0001 to 0.9999).
3110 High values sacrifice performance for stability.
3111
3112- Added parameters benders/<bendersname>/lnsmaxcalls and benders/<bendersname>/lnsmaxcallsroot to the Benders'
3113 decomposition core. These parameters limit the number of Benders' decomposition subproblem checks, for the full
3114 branch-and-bound tree and root node respective, when solving the auxiliary problem of LNS hueristics. These
3115 parameters only have effect if the lnscheck parameter is set to TRUE.
3116
3117- Added parameter cons/linear/maxmultaggrquot to limit the maximum coefficient dynamism of an equation on which
3118 multiaggregation is performed. This replaces a compiler define of the same name.
3119 Default value is 1000, smaller values make multiaggregations numerically more stable.
3120- new global parameter heuristics/useuctsubscip that affects all LNS heuristics using common sub-SCIP parameters
3121
3122- new parameter branching/relpscost/degeneracyaware to switch degeneracy-aware hybrid branching
3123
3124- new parameter separation/rapidlearning/checkexec to check whether rapid learning is allowed to run locally
3125- new parameters separation/rapidlearning/check{degeneracy,dualbound,leaves,nsols,obj} to enable checking the respective feature for local rapid learning
3126- new parameter separation/rapidlearning/maxcalls to limit the number of rapid learning executions
3127- new parameter separation/rapidlearning/nwaitingnodes to set the number of waiting nodes before the dual bound is checked
3128- new parameter separation/rapidlearning/mindegeneracy to set the minimal threshold of degenerate basic-variables
3129- new parameters separation/rapidlearning/minvarconsratio to set the minimal ratio of unfixed variables in relation to basis size
3130
3131- new parameters to control the Benders' decomposition two-phase method.
3132 - constraints/benderslp/depthfreq: after the maxdepth is reached, then the two-phase method will only be called at
3133 nodes at a depth divisible by depthfreq.
3134 - constraints/benderslp/stalllimit: after the maxdepth is reached, if there has been no improvement in the dual bound
3135 for stalllimit number of nodes, then the two-phase method is executed for the next fractional LP solution that is
3136 encountered.
3137 - constraints/benderslp/iterlimit: after the root node, only iterlimit fractional LP solutions are used at each node
3138 to generate Benders' decomposition cuts.
3139
3140- new parameters for symmetry handling
3141 - new parameter "propagating/symmetry/maxgenerators"
3142 - new parameter "propagating/symmetry/checksymmetries"
3143 - new parameter "propagating/symmetry/displaynorbitvars"
3144 - new parameter "propagating/symmetry/conssaddlp"
3145 - new parameter "propagating/symmetry/addsymresacks"
3146 - new parameter "propagating/symmetry/detectorbitopes"
3147 - new parameter "propagating/symmetry/addconsstiming"
3148 - new parameter "propagating/symmetry/ofsymcomptiming"
3149 - new parameter "propagating/symmetry/performpresolving"
3150 - new parameter "propagating/symmetry/recomputerestart"
3151 - new parameter "constraints/symresack/checkmonotonicity"
3152 - new parameter "propagating/symmetry/compresssymmetries"
3153 - new parameter "propagating/symmetry/compressthreshold"
3154 - new parameter "propagating/symmetry/disableofrestart"
3155 - new parameter "propagating/symmetry/symfixnonbinaryvars"
3156
3157- new parameter for enabling shared memory parallelisation for solving Benders' decomposition subproblems. The parameter
3158 benders/<bendersname>/numthreads sets the number of threads used for parallel subproblem solving.
3159
3160- new parameters to control enhancements for solving MINLPs by Benders' decomposition
3161 - benders/<bendersname>/execfeasphase: enables the feasibility phase for solving the Benders' decomposition
3162 subproblems
3163 - benders/<bendersname>/slackvarcoef: the initial coefficient of the slack variable for the feasibility phase
3164 - benders/<bendersname>/checkconsconvexity: should the constraints be checked for convexity. This can be set to FALSE
3165 if you are certain that the NLP subproblem is convex.
3166
3167- new parameter presolving/clqtablefac (default value 2.0) as limit on number of entries in clique table relative to number of problem nonzeros
3168
3169- new parameter conflict/uselocalrows (default: TRUE) to incorporate locally valid cuts / rows for dual proof analysis
3170
3171- new return code SCIP_NOTIMPLEMENTED for functions, e.g., in the LPI that have not been implemented (yet)
3172
3173- new parameter separating/cgmip/genprimalsols that allows to generate initial primal solutions from Gomory cuts
3174
3175- new parameter branching/relpscost/filtercandssym to allow filtering from orbits
3176
3177- new parameter branching/relpscost/transsympscost to transfer pseudo cost information to orbit
3178
3179- new parameters for tree size estimation and restarts:
3180 - estimation/restarts/restartpolicy (default value n)
3181 - estimation/method (default value c)
3182 - estimation/restarts/restartlimit (default value 1)
3183 - estimation/restarts/minnodes (default value 1000)
3184 - estimation/restarts/countonlyleaves (default value FALSE)
3185 - estimation/restarts/restartfactor (default value 2)
3186 - estimation/coefmonoprog (default value 0.3667)
3187 - estimation/coefmonossg (default value 0.6333)
3188 - estimation/restarts/hitcounterlim (default value 50)
3189 - estimation/reportfreq (default value -1)
3190 - estimation/regforestfilename (default value "-")
3191 - estimation/completiontype (default value a)
3192 - estimation/treeprofile/enabled (default value FALSE)
3193 - estimation/treeprofile/minnodesperdepth (default value 20)
3194 - estimation/useleafts (default value TRUE)
3195 - estimation/ssg/nmaxsubtrees (default value -1)
3196 - estimation/ssg/nminnodeslastsplit (default value 0)
3197
3198- new parameter constraints/linear/extractcliques to turn clique extraction off
3199
3200- new emphasis setting emphasis/numerics to increase numerical stability of (mostly) presolving operations such as (multi-)aggregations at the cost of performance.
3201
3202- new parameters for treemodel:
3203 - new parameter branching/treemodel/enable to enable the treemodel in reliability pscost branching and possible
3204 future parts of the code where it could be used.
3205 - new parameter branching/treemodel/highrule to specify which branching rule to use when treemodel thinks the node
3206 is high in the tree.
3207 - new parameter branching/treemodel/lowrule to specify which branching rule to use when treemodel thinks the node
3208 is low in the tree.
3209 - new parameter branching/treemodel/height to specify at which (estimated) height a node is high or low in the tree.
3210 - new parameter branching/treemodel/filterhigh to specify whether to filter dominated candidates in nodes which are
3211 high in the tree.
3212 - new parameter branching/treemodel/filterlow to specify whether to filter dominated candidates in nodes which are
3213 low in the tree.
3214 - new parameter branching/treemodel/maxfpiter to specify the maximum number of fixed-point iterations to use when
3215 computing the ratio of a variable using the fixed-point method.
3216 - new parameter branching/treemodel/maxsvtsheight to specify the maximum height to compute the SVTS score exactly
3217 before approximating it using the ratio.
3218 - new parameter branching/treemodel/fallbackinf defines the fallback strategy to use when the tree size estimates
3219 obtained by SVTS are infinite.
3220 - new parameter branching/treemodel/fallbacknoprim defines the fallback strategy to use when no primal bound is known
3221 and thus SVTS would not be able to compute a tree size (it would be infinite).
3222 - new parameter branching/treemodel/smallpscost defines the value under which pscosts are considered too small to be
3223 the deciding factor for branching, in which case it may be better not to use the treemodel.
3224
3225- new parameters for symmetry handling constraint handlers to enforce that also non-model constraint are copied:
3226 - new parameter "constraints/orbisack/forceconscopy"
3227 - new parameter "constraints/orbitope/forceconscopy"
3228 - new parameter "constraints/symresack/forceconscopy"
3229
3230
3231### Data structures
3232
3233- small changes in constants of hash functions
3234- added fast 2-universal hash functions for two to seven 32bit elements with 32bit output
3235- extended SCIPpqueueCreate() by additional callback argument SCIP_DECL_PQUEUEELEMCHGPOS to catch position changes
3236- new methods SCIPpqueueDelPos() to delete elements at a specific position in the priority queue and SCIPpqueueFind() to
3237 find a specific position. It is recommended to track position changes using the new callback SCIP_DECL_PQUEUEELEMCHGPOS.
3238 In contrast, using SCIPpqueueFind() can be slow because it needs to compare the element it searches for
3239 with each slot in the queue.
3240
3241### Build system
3242
3243- The default value for DFLAGS in the non-cmake buildsystem has changed from -MM to -MMD. This will break the
3244 generation of depend.* files if that was done by a compiler call that relied on -MM. The new preferred way
3245 to handle compilation dependencies is to additionally use $(DFLAGS) when compiling the object files (.o) and
3246 to include the generated .d files in the Makefile, see also "Build system / Makefile" below.
3247
3248Unit tests
3249----------
3250 - new unit test for treemodel.
3251
3252Testing
3253-------
3254
3255 - fixed an issue that may have lead to wrong status reports in the evaluation scripts
3256
3257Build system
3258------------
3259
3260### Cmake
3261
3262- avoid problem with doubly defined object together with CPLEX
3263
3264### Makefile
3265
3266- Removed static object compilation dependency files (depend.*). If using a GCC compatible compiler, then dependency
3267 files are now dynamically created and updated during build. The new dependency files (*.d) reside next to each object
3268 file (.o) in the corresponding obj subdirectory.
3269- added support for building against Ipopt >= 3.13
3270- unify compiler switches for Intel compiler and avoid problem with doubly defined object together with CPLEX
3271
3272Fixed bugs
3273----------
3274
3275- fix and improve memory handling in symmetry computation
3276- fix shown number of applied conflicts in solving statistics
3277- fix wrongly skipping strong branching call and using old information if LP was solved with 0 iterations
3278- fix minor bug in cut score calculation
3279- fixed several bugs related to rounding locks of variables not being updated correctly
3280- small fix in cons_varbound.c to skip changing bounds of multi-aggregated variables in separation callback
3281- fixed issue in SCIPtightenVar* and SCIPinferVar* that occurs for small bound changes
3282- fixed rejecting minimal boundchange that changed sign of variable, even though SCIPisLb/UbBetter approved it
3283- fixed issue in generateCutNonConvex() which is triggered when adding quadratic constraints during the solving process
3284- fixed bug in freeing the reoptimization data if no problem exists
3285- fixed bug in SCIPreoptReleaseData() when freeing all stored constraints
3286- fixed bug when freeing the transformed problem via interactive shell if reoptimization is enabled
3287- fixed two issues related to (near-)redundant logicor constraints in presolving
3288- fixed counting of aggregations in XOR constraint handler
3289- fixed handling of unbounded solutions
3290- fixed update of LP size information when an LP error occurred during probing
3291- handle special case of variable bound constraints during aggregating variables
3292- tighten sides of linear constraints before trying to upgrade them to more specialized constraints (knapsack, logic-or etc.) when calling SCIPupgradeConsLinear()
3293- fixed an issue in repair heuristic in the case of loose (noncolumn) variables
3294- allow user to correctly set heuristics/alns/(un)fixtol
3295- fixed an issue in heur_completesol which is triggered during bound widening of unbounded continuous variables
3296- fixed bug in cons_indicator if addopposite is true
3297- fixed bug in sepa_disjunctive: treat case that conflictgraph is empty
3298- added safety check in conversion to rational number to avoid overflow
3299- fixed bug in interval evaluation with power-operator in certain situations
3300- fixed behavior of SCIPmatrixCreate() regarding memory management and column generation
3301- SCIPmatrixCreate() returns complete=FALSE when locks do not add up
3302- fixed bug in sepa_oddcylce when variables are fixed
3303- fixed numerical issues related to tighter constraint sides in varbound constraint handler
3304- fixed update of watchedvars in logicor constraint handler in case of a restart during the tree
3305- fixed treatment of multi-aggregated variables in logicor constraint handler
3306- handle special case of redundant implications
3307- fixed numerical issue related to almost-0-values in pseudosolution conflict analysis
3308- fixed numerical issue related to very large greatest common dividers in linear constraint handler
3309- avoid using implications on multiaggregated variables when propagating implications
3310- fixed creation of (Lagrangian) variable bounds in the OBBT propagator
3311- fixed sorting of primal solutions
3312- fixed cleaning of clean buffer in conflict analysis
3313- avoid probing on variables with huge bounds in shift and propagate heuristic
3314- fix issue in printing solutions for variables that have been added by the dual sparsify presolver
3315- fix issue related to fixing redundant logic-or constraints after presolving
3316- fixed bug when parsing logic-or and and-constraints
3317- fixed wrong assert in updateLazyBounds()
3318- fixed bug in pricestore, which resulted in too many problem variables being added
3319- fixed bug in cons_knapsack where weight of clique was not reset after an infeasibility was detected
3320- fixed bug in presol_inttobinary which did not take into account that the aggregation could be rejected due to numerics
3321- fixed bug in debug solution mechanism in connection to variables created by presol_inttobinary
3322- fixed wrong indexing while undoing the implications from a redundant variable in SCIPshrinkDisjunctiveVarSet
3323- redundancy checks in SCIPnodeAddBoundinfer now take a possible change to an active variable into account
3324- fixed adding already added quadratic rows to NLP relaxation during solve
3325- fixed issue related to variable locks in the varbound constraint handler
3326- fixed bug in the quadratic constraint handler when changing infinite constraint sides
3327- fixed sorting of variables in linear constraint handler
3328- added additional checks to ensure numerical stability of dual proofs
3329- fixed a case when activities of a linear constraint got unreliable but where still used for reductions
3330- ensure that lhs <= rhs for linear constraints (without tolerances)
3331- make handling of read errors in SCIPfread() consistent between version with and without ZLIB
3332- correctly drop variable events in cons_indicator in restart
3333- fixed bug in cons_orbitope with upgrading of orbitope constraints
3334- additional checks in some presolvers for time limit being exceeded
3335- fixed bug in presolving of cons_varbound with multi-aggregated variables
3336- improve numerics in conflict analysis by using double-double arithmetic
3337- fixed bound acceptance condition to avoid inconsistencies
3338- fixed numerics in pseudoobj propagator by using double-double arithmetic
3339
3340Miscellaneous
3341-------------
3342
3343- modified display column for memory usage ("mem"), which reports the memory usage most of the time, but shows the creator name
3344 (heuristic, relaxation handler, LP relaxation, strong branching, pseudo solution) of every new incumbent solution. Together with this change,
3345 heuristic display characters have been unified to represent the type of the heuristic
3346 (diving, Large neighborhood search, propagation, etc.), see also type_heur.h.
3347- added assert that ensures that the locks of a variable have been decreased to 0 when it is freed
3348- added more output for completing a partial solution
3349- checks in debug mode that clean buffer memory is really clean when being freed are now disabled by default
3350- don't compute symmetries if reoptimization is enabled
3351- prefer integral values when fixing an almost-fixed continuous variable in the trivial presolver
3352- changed the name of the variable that is added by the OSiL reader to represent the quadratic or nonlinear parts of the objective function
3353- SCIP_EXPORT is now defined as __attribute__((__visibility__("default"))) if GCC and no SCIP config header is used
3354
3355@page RN6 Release notes for SCIP 6
3356
3357@section RN602 SCIP 6.0.2
3358*************************
3359
3360Features
3361--------
3362
3363- The abspower constraint handler now passes more accurate convexity
3364 information to the NLP relaxation.
3365
3366Examples and applications
3367-------------------------
3368
3369- added parsing functionality for optcumulative constraints in CIP format
3370
3371Interface changes
3372-----------------
3373
3374### Interfaces to external software
3375
3376- Updated the Mosek LP solver interface to support Mosek 9.0.
3377
3378Build system
3379------------
3380
3381### Cmake
3382
3383- new target to 'doc' to build documentation
3384- ctests now fail if parameter file not found
3385- add flag STATIC_GMP and improve GMP find module
3386- remove non-API functions from library (API functions use new macro SCIP_EXPORT)
3387- increase minimal required CMake version to 3.3
3388- correct paths and dependency information when installing SCIP
3389
3390Fixed bugs
3391----------
3392- fixed SCIP-Jack presolving bug that could lead to wrong results for Steiner arborescence problems
3393- fixed wrong unboundedness result in case not all constraints were already in the LP and enforcement was
3394 skipped because an optimal solution was found
3395- fixed wrong enforcement of constraints in the disjunction constraint handler
3396- fixed wrong behavior of concurrent solve ignoring initial solutions
3397- fixed bug in concurrent solve when problem was already solved in presolving
3398- aggregate non-artificial integer variable for XOR constraints with two binary variables and delete constraint
3399- copy the objective offset when copying the original problem
3400- fixed bug in SCIPlpiGetBInvARow in lpi_cpx using wrong size of resulting vector
3401- fixed quadratic runtime behavior in sepa_aggregation
3402- fixed statistics of separators
3403- improve numerical stability in varbound constraint handler by using double-double arithmetic
3404- fixed bug in propagation of dual proofs
3405- fixed bugs that arise for multiaggregated indicator variables by disallowing multiaggregation for them
3406- improve numerical stability in SCIPcomputeBilinEnvelope* by using double-double arithmetic
3407- fixed bug related to releasing pending bound changes in tree.c
3408- set STD FENV_ACCESS pragma to on in code that changes floating-point rounding mode
3409- disable GCC optimizations in main interval arithmetic code to prevent wrong optimizations
3410- fixed wrong assert in cons_xor concerning the variable type
3411- fixed different behavior of SCIPisLbBetter and SCIPisUbBetter between having NDEBUG defined or not
3412- correctly handle bound disjunctions in symmetry detection
3413- fixed issue in reliability branching related to the LP error flag not being reset
3414- fixed treatment of near-infinite bounds in shiftandpropagate's problem transformation
3415- fixed handling of infinite values in SCIPcomputeHyperplaneThreePoints()
3416- fixed comparisons of infinite values in heur_intshifting.c and heur_shifting.c
3417- fixed bug related to updating unprocessed cuts in the cutpool
3418- fixed bug related to enabling quadratic constraints during `CONSINITLP`
3419- add missing SCIP_EXPORT for functions used by GCG
3420- fixed memory leak and wrong initialization for trival cases in cons_symresack.c
3421- fixed bug with upgrading to packing/partitioning orbitopes
3422- fixed bug with the status while upgrading in presol_symbreak.c
3423- fixed wrong stage while clearing the conflict store
3424- fixed behavior of SCIPfixVar() by setting infeasible pointer to TRUE if fixval lies outside variable domain
3425- allow tightenVar() in SCIP_STAGE_PROBLEM stage
3426- fixed bug in cumulative constraint handler when separating the LP solution
3427- fixed issues with integer overflow in cumulative constraint handler
3428- fixed bug where the convexity of Benders' decomposition subproblems was checked even when users defined subproblem
3429 solving methods. Now, as per the documentation, the user must explicitly state whether the subproblem is convex
3430- fixed wrong indexing in heur_dualval
3431- fixed issue with basis status in SoPlex LPi
3432
3433Miscellaneous
3434-------------
3435
3436- statistics now output primal/dual bounds if objective limit is reached
3437- memory check in debug mode is now disabled by default
3438- message is now provided to the user to inform that automatic Benders' auxiliary variable lower bound computations are
3439 not activated when user defined subproblem solving methods are present
3440- corrected documentation of the primalgap in SCIP; describe when it will be infinite
3441
3442@section RN601 SCIP 6.0.1
3443*************************
3444
3445Features
3446--------
3447
3448- when using a debug solution every (multi-)aggregation will be checked w.r.t. this solution
3449
3450Performance improvements
3451------------------------
3452
3453- try greedy solution first before solving knapsack exactly using dynamic programming in SCIPsolveKnapsackExactly,
3454 compute greedy solution by weighted median selection.
3455- don't consider implied redcost by default in the reduced cost propagator
3456
3457Interface changes
3458-----------------
3459
3460### Deleted and changed API functions and macros
3461
3462- The preprocessor macro NO_CONFIG_HEADER now needs to be defined when
3463 including SCIP header files from a SCIP build or installation that
3464 has been build via the Makefile-only build system.
3465
3466- The following preprocessor macros have been renamed:
3467 WITH_ZLIB to SCIP_WITH_ZLIB, WITH_GMP to SCIP_WITH_GMP, WITH_READLINE
3468 to SCIP_WITH_READLINE, NO_SIGACTION to SCIP_NO_SIGACTION, NO_STRTOK_R
3469 to SCIP_NO_STRTOK_R, ROUNDING_FE to SCIP_ROUNDING_FE, ROUNDING_FP to
3470 SCIP_ROUNDING_FP, ROUNDING_MS to SCIP_ROUNDING_MS. Note, however, that
3471 the names of macros NO_RAND_R and NO_STRERROR_R have not been changed
3472 so far.
3473
3474### New API functions
3475
3476- SCIPhashmapInsertInt(), SCIPhashmapSetImageInt(), and SCIPhashmapGetImageInt() to use integer values as images in hashmaps
3477
3478### Command line interface
3479
3480- warn about coefficients in MPS files with absolute value larger than SCIP's value for infinity
3481
3482### Changed parameters
3483
3484- default clock type for timing is now wallclock
3485
3486Unit tests
3487----------
3488
3489- added unit tests for exact knapsack solving and (weighted) median selection algorithms
3490
3491Build system
3492------------
3493
3494### Cmake
3495
3496- add missing GMP dependency when compiling with SYM=bliss
3497- add DL library when linking to CPLEX to avoid linker errors
3498- new config.h header defining the current build configuration, e.g. SCIP_WITH_GMP
3499
3500Fixed bugs
3501----------
3502
3503- fixed handling of weights in cons_sos1 and cons_sos2 (NULL pointer to weights)
3504- fixed handling of unbounded LPs in SCIP and in several LPIs; added heuristic method to guess solution
3505- the STO reader is capable of handling scenarios defined using lower case "rhs"
3506- fixed OPB reader for instances without explicit plus signs
3507- correct dual solution values for bound constraints
3508- fixed recognition of variable with only one lock in cons_bivariate, cons_quadratic, and cons_nonlinear
3509- fixed update of constraint violations in solution repair in cons_bivariate, cons_quadratic, and cons_nonlinear
3510- print error message and terminate if matrix entries of a column are not consecutive in mps format
3511- fixed incorrect handling of fixed variables when transfer of cuts from LNS heuristic for Benders' decomposition
3512- fix returning local infeasible status by Ipopt interface if Ipopt finds problem locally infeasible
3513- skip attempt to apply fixings in linear constraint handler during solving stage as LP rows cannot change anymore
3514- fixed bug when reading >= indicator constraints in MPS format
3515- fix issue with nodes without domain changes if we ran into solution limit in prop_orbitalfixing
3516- fixed unresolved reference to CppAD's microsoft_timer() function on builds with MS/Intel compilers on Windows
3517- ignore implications added through SCIPaddVarImplication() that are redundant to global bounds also in the
3518 special case of an implication between two binary variables; also, use implications instead of cliques in the case
3519 of a binary implied variable with nonbinary active representative
3520- fixed bug with aggregated variables that are aggregated in propagation of cons_sos1
3521- fixed some special cases in SCIPselect/SCIPselectWeighted methods
3522- relaxed too strict assertion in Zirounding heuristic
3523- fixed the upgrade routine to XOR constraints: aggregate integer variable if its coefficient has the wrong sign
3524- fixed handling of nonartificial parity variables when deleting redundant XOR constraints
3525- earlier deletion of trivial XOR constraints (at most 1 operator left)
3526- fixed wrong hashmap accesses and added sanity check for the correct hashmap type
3527- avoid copying of unbounded solutions from sub-SCIPs as those cannot be checked completely
3528- corrected the output of the first LP value in case of branch-and-price
3529- fixed possible integer overflow, which led to wrong conclusion of infeasibility, in energetic reasoning of cons_cumulative.c
3530
3531Miscellaneous
3532-------------
3533
3534- do not scale linear constraints to integral coefficients
3535
3536@section RN600 SCIP 6.0.0
3537*************************
3538
3539Features
3540--------
3541
3542- new diving heuristic farkasdiving that dives into the direction of the pseudosolution and tries to construct Farkas-proofs
3543- new diving heuristic conflictdiving that considers locks from conflict constraints
3544- restructuring of timing of symmetry computation that allows to add symmetry handling components within presolving
3545- `lp/checkstability` is properly implemented for SoPlex LPI (spx2)
3546- new branching rule lookahead that evaluates potential child and grandchild nodes to determine a branching decision
3547- limits on the number of presolving rounds a presolver (maxrounds) or propagator/constraint handler (maxprerounds)
3548 participates in are now compared to the number of calls of the particular presolving method, not the number of
3549 presolving rounds in general, anymore
3550- new miscellaneous methods for constraints that have a one-row linear representation in pub_misc_linear.h
3551- a Benders' decomposition framework has been added. This framework provides the functionality for a user to solve a
3552 decomposed problem using Benders' decomposition. The framework includes classical optimality and feasibility cuts,
3553 integer optimality cuts and no-good cuts.
3554- add statistic that presents the number of resolves for instable LPs
3555- new readers for stochastic programming problems in SMPS format (reader_sto.h, reader_smps.h)
3556
3557Performance improvements
3558------------------------
3559
3560- cuts generated from certain quadratic constraints with convex feasible region are now global
3561- performance improvements for Adaptive Large Neighborhood Search heur_alns.c
3562 + all neighborhoods now start conservatively from maximum fixing rate
3563 + new default parameter settings for bandit selection parameters
3564 + no adjustment of minimum improvement by default
3565- improved bound tightening for some quadratic equations
3566- constraint handler checking order for original solutions has been modified to check those with negative check priority
3567 that don't need constraints after all other constraint handlers and constraints have been checked
3568- deactivate gauge cuts
3569
3570Examples and applications
3571-------------------------
3572
3573- new example `brachistochrone` in CallableLibrary examples collection; this example implements a discretized model to
3574 obtain the trajectory associated with the shortest time to go from point A to B for a particle under gravity only
3575- new example `circlepacking` in CallableLibrary examples collection; this example models two problems about packing
3576 circles of given radii into a rectangle
3577- new price-and-branch application for the ringpacking problem
3578- new stochastic capacitated facility location example demonstrating the use of the Benders' decomposition framework
3579
3580Interface changes
3581-----------------
3582
3583### New and changed callbacks
3584
3585- added parameter locktype to `SCIP_DECL_CONSLOCK` callback to indicate the type of variable locks
3586
3587### Deleted and changed API functions
3588
3589- Symmetry:
3590 + removed function SCIPgetTimingSymmetry() in presol_symmetry.h since this presolver does not compute symmetries independent
3591 of other components anymore
3592 + additional argument `recompute` to SCIPgetGeneratorsSymmetry() to allow recomputation of symmetries
3593
3594- Random generators:
3595 + the seed of SCIPinitializeRandomSeed() is now an unsigned int
3596 + the seed of SCIPsetInitializeRandomSeed() is now an unsigned int and it returns an unsigned int
3597 + new parameter for SCIPcreateRandom() to specify whether the global random seed shift should be used in the creation of
3598 the random number generator
3599
3600- Miscellaneous:
3601 + additional arguments `preferrecent`, `decayfactor` and `avglim` to SCIPcreateBanditEpsgreedy() to choose between
3602 weights that are simple averages or higher weights for more recent observations (the previous default).
3603 The last two parameters are used for a finer control of the exponential decay.
3604 + functions SCIPintervalSolveUnivariateQuadExpression(), SCIPintervalSolveUnivariateQuadExpressionPositive(), and
3605 SCIPintervalSolveUnivariateQuadExpressionPositiveAllScalar() now take an additional argument to specify already
3606 existing bounds on x, providing an entire interval ([-infinity,infinity]) gives previous behavior
6701 - added writing for pip files (linear, quadratic, polynomial nonlinear, polynomial abspower, polynomial bivariate, and
6702 and constraints)
6703 - CIP format variable characters defined, e.g. `SCIP_VARTYPE_INTEGER_CHAR`
6704 - Improved support for wbo format for weighted PBO problems, IBM's xml-solution
6705 format and pip and zimpl format for polynomial mixed-integer programs
6706 - New reader for (standard) bounds on variables
6707 - Extended reader for CIP models to handle various new constraints, including all types of linear constraints
6708 - flatzinc reader is now capable to read cumulative constraints
6709 - changed opb(/wbo) reader which now creates pseudoboolean constraints instead of linear- and and-constraints, only a
6710 non-linear objective will create and-constraints inside the reader and while reading a wbo file the topcost constraint
6711 is created as well
6712 - added clock for determine the time for reading
6713 - added reader for variable bounds (reader_bnd.{c,h})
6714 - Removed method SCIPreadSol(); call solution reading via SCIPreadProb() which calls the solution reader for .sol files.
6715
6716- Nonlinear:
6717 - Major extensions for nonlinear CIP, new option for n-ary branching on nonlinear variables (within pseudocost branching rule)
6718 - added BETA version of constraint handler for nonlinear constraints (cons_nonlinear.{c,h}) to handle nonlinear
6719 equations given by algebraic expressions using operands like addition, multiplication, power, exp, log, bivariate
6720 nonlinear constraints; currently no trigonometric functions
6721 - added BETA version of constraint handler for bivariate nonlinear constraints (cons_bivariate.{c,h}) to compute tight
6722 estimators for 1-convex and convex-concave bivariate nonlinear functions (given as expression tree)
6723 - the gams writer can now write nonlinear, abspower and bivariate constraints
6724 - Extended writer for GAMS and pip format to write more types of nonlinear constraints
6725 - the pip and zimpl reader now create nonlinear constraints for polynomials of degree > 2
6726
6727- Presolving:
6728 - new dual presolving methods in cons_setppc and cons_logicor
6729 - new presolving step `removeConstraintsDueToNegCliques` in locigor constraint handler which updates logicor constraints
6730 to setppc constraints if a negated clique inside this constraint exist, by default is off
6731 - new presolving step in cons_knapsack (detectRedundantVars, deleteRedundantVars) which determines redundant variables
6732 in knapsack constraint with or without using clique information
6733 - cons_logicor is now able to replace all aggregated variables in presolving by there active or negation of an active
6734 variable counterpart
6735 - prop_pseudoobj is now working in presolving as well
6736 - implement presolving in exitpre() in cons_orbitope and cons_indicator
6737
6738- Propagators:
6739 - added counter for number calls and timing for resolve propagation calls for constraint handler and propagators
6740 - Propagators are now also called in node presolving
6741 - the probing presolver presol_probing.{c.h} is now a propagator prop_probing.{c,h}, all corresponding parameters moved as well
6742 - the redcost separator sepa_redcost.{c.h} is now a propagator prop_redcost.{c,h}, all corresponding parameters moved as well
6743 - outsourced propAndSolve() method in solve.c which calls domain propagation and solving of the lp and relaxation
6744
6745- Statistic:
6746 - solutions which are given by the user from the outside are now marked by `#` in the output
6747 - the `Solving Time` is now spitted into presolving, solving and reading time
6748 - Presolvers section has new column `AddCons` which states the number of added constraint
6749 - Constraints section has new column named \#ResProp which show the number of resolve propagation calls of certain
6750 constraint handler
6751 - Constraint Timing section has a new column \#ResProp which states the time spend in resolve propagation method of the
6752 constraint handler
6753 - improved output of propagators in display statistics
6754 - new section `Propagator Timing` which shows the time spend in different callbacks of the propagator
6755 - rearranged first two columns of Propagators section; \#Propagate and \#ResProp stating the number of call for
6756 propagation and resolve propagation; the Time column is moved into the new section Propagator Timings
6757 - Constraints section has new column named `MaxNumber` which the maximum number of active constraint of a certain
6758 constraint handler
6759 - added two columns `Time-0-It` and `Calls-0-It` in the LP section which states the number of LP call and time spend for
6760 solving LPs with zero iterations (only refactorization)
6761 - The display of statistics for presolvers, propagators, constraints and LP solving has changed.
6762
6763Performance improvements
6764------------------------
6765
6766- Reorganized filtering process of separation storage (allows adding cuts for different solutions)
6767- Improved presolving for various constraint handlers
6768- Improved propagation methods for variable bound constraints
6769- Improved performance for quadratic constraints
6770- performance improvements in prop_vbounds
6771- child selection rules now get also applied when the relaxation value is equal to the bound changed in branching
6772- added dual reduction to cons_cumulative.c
6773- for continuous variables, the pseudo costs update and the pscost branching rule now use the same strategies for
6774 updating the pseudo costs and estimating the improvement in the LP bound
6775- only perform probing if the variables are locked
6776- performance and memory consumption improvements in xmlparse.c
6777- Improved knapsack cover cuts
6778- avoid very long separation times of LEWIs in cons_knapsack for very large minimal covers
6779- used SCIPallocMemoryArray() instead of SCIPallocBlockMemoryArray() which leads to fewer memory consumption in
6780 getLiftingSequence() in cons_knapsack, also improved cache use bei using an extra array instead blockmemory chunks
6781- switched FASTMIP from 1 to 2 for CPLEX and changed default pricing rule back to steepest edge pricing instead of
6782 quickstart steepest edge pricing
6783- made sorting method more robust
6784- LNS heuristics now use SCIPcopy() by default
6785- considering inactive variables in undercover heuristic; limiting effort for solving covering problem
6786- if during probing mode the LP relaxation is solved from scratch, e.g., when calling the shiftandpropagate heuristic
6787 before root node solving, then we clear the resulting LP state, since it might be a bad starting basis for the next
6788 solve of the LP relaxation (controlled by new parameter `lp/clearinitialprobinglp`)
6789- included LP simplifier into SoPlex LP interface, applied when solving from scratch (lpi_spx.cpp)
6790- new presolving steps in varbound constraint handler, tightening bounds, coefficients, sides and pairwise presolving
6791
6792Interface changes
6793-----------------
6794
6795- Miscellaneous:
6796 - The emphasis setting types now distinguish between plugin-type specific parameter settings (default, aggressive, fast, off),
6797 which are changed by SCIPsetHeuristics/Presolving/Separating(), and global emphasis settings (default, cpsolver, easycip,
6798 feasibility, hardlp, optimality, counter), which can be set using SCIPsetEmphasis().
6799
6800### New and changed callbacks
6801
6802- added propagator timings `SCIP_PROPTIMING_BEFORELP`, `SCIP_PROPTIMING_DURINGLPLOOP` and `SCIP_PROPTIMING_AFTERLPLOOP` for
6803 all propagation callbacks (see propagators and constraint handlers) which lead to calling the propagation methods of a
6804 propagator before the lp is solved, during the lp loop and after the lp solving loop
6805
6806- Conflict Analysis:
6807 - Added parameter `separate` to conflict handler callback method SCIP_DECL_CONFLICTEXEC() that defines whether the conflict
6808 constraint should be separated or not.
6809
6810- Constraint Handler:
6811 - The new constraint handler callback SCIP_DECL_CONSDELVARS() is called after variables were marked for deletion.
6812 This method is optional and only of interest if you are using SCIP as a branch-and-price framework. That means,
6813 you are generating new variables during the search. If you are not doing that just define the function pointer
6814 to be `NULL`.
6815 If this method gets implemented you should iterate over all constraints of the constraint handler and delete all
6816 variables that were marked for deletion by SCIPdelVar().
6817
6818- NLP Solver Interface:
6819 - The callbacks SCIP_DECL_NLPIGETSOLUTION() and SCIP_DECL_NLPISETINITIALGUESS() got new parameters to get/set values of
6820 dual variables.
6821 - The callback SCIP_DECL_NLPICOPY() now passes the block memory of the target SCIP as an additional parameter.
6822
6823- Presolving:
6824 - New parameters `isunbounded` and `isinfeasible` for presolving initialization (SCIP_DECL_CONSINITPRE(),
6825 SCIP_DECL_PRESOLINITPRE(), SCIP_DECL_PROPINITPRE()) and presolving deinitialization (SCIP_DECL_CONSEXITPRE(),
6826 SCIP_DECL_PRESOLEXITPRE(), SCIP_DECL_PROPEXITPRE()) callbacks of presolvers,
6827 constraint handlers and propagators, telling the callback whether the problem was already declared to be
6828 unbounded or infeasible. This allows to avoid expensive steps in these methods in case the problem is already
6829 solved, anyway.
6830
6831 Note, that the C++ methods
6832 - scip::ObjConshdlr::scip_presol() corresponding to SCIP_DECL_CONSPRESOL()
6833 - scip::ObjConshdlr::scip_initpre() corresponding to SCIP_DECL_CONSINITPRE()
6834 - scip::ObjPresol::scip_initpre() corresponding to SCIP_DECL_PRESOLINITPRE()
6835 - scip::ObjProp::scip_initpre() corresponding to SCIP_DECL_PROPINITPRE()
6836 - scip::ObjConshdlr::scip_exitpre() corresponding to SCIP_DECL_CONSEXITPRE()
6837 - scip::ObjPresol::scip_exitpre() corresponding to SCIP_DECL_PRESOLEXITPRE()
6838 - scip::ObjProp::scip_exitpre() corresponding to and SCIP_DECL_PROPEXITPRE()
6839 are virtual functions. That means, if you are not adding the new parameters, your code will still compile, but these methods are not executed.
6840 - Propagators are now also called in during presolving, this is supported by the new callback methods SCIP_DECL_PROPINITPRE(),
6841 SCIP_DECL_PROPEXITPRE(), and SCIP_DECL_PROPPRESOL().
6842 - The new parameters `nnewaddconss` and `naddconss` were added to the constraint handler callback method SCIP_DECL_CONSPRESOL()
6843 and the presolver callback method SCIP_DECL_PRESOLEXEC(). These parameters were also added to corresponding C++ wrapper
6844 class methods (scip_presol() in objconshdlr.h and scip_exec() in objpresol.h)
6845
6846- Problem Data:
6847 - The callback SCIP_DECL_PROBCOPY() got a new parameter `global` to indicate whether the global problem or a local version is copied.
6848
6849### Deleted and changed API functions
6850
6851- implemented SCIPlpiGetPrimalRay() in SoPlex interface that has become available with SoPlex version 1.5.0.2
6852- allowed calling SCIPgetRowSolActivity() in `SCIP_STAGE_SOLVED`, since LP is still available
6853- various extensions and modifications for expressions and expression trees (too much to state here)
6854- The result value `SCIP_NEWROUND` has been added, it allows a separator/constraint handler to start a new separation round
6855 (without previous calls to other separators/conshdlrs).
6856- SCIPcalcNodeselPriority() got a new parameter `branchdir`, which defines the type of branching that was performed: upwards, downwards, or fixed.
6857
6858- Constraint Handlers:
6859 - Method SCIPincludeQuadconsUpgrade() of quadratic constraint handler got new parameter `active` to indicate whether the upgrading method is active by default.
6860 - Method SCIPseparateRelaxedKnapsack() in knapsack constraint handler got new parameter `cutoff`, which is a pointer to store whether a cutoff was found.
6861
6862- Nonlinear expressions, relaxation, and solver interface:
6863 - SCIPcreateNLPSol() now creates a `SCIP_SOL` that is linked to the solution of the current NLP relaxation
6864 - Various types and functions dealing with polynomial expressions have been renamed to use the proper terms `monomial` and
6865 `polynomial` in nonlinear expressions (nlpi/∗expr*); results in many renamings of types, structs and methods.
6866 - The methods SCIPnlpGetObjective(), SCIPnlpGetSolVals(), and SCIPnlpGetVarSolVal() have been removed, use SCIPgetNLPObjval(),
6867 SCIPvarGetNLPSol() and SCIPcreateNLPSol() to retrieve NLP solution values instead.
6868 SCIPcreateNLPSol() now returns an error if NLP or NLP solution is not available
6869 - Removed methods SCIPmarkRequireNLP() and SCIPisNLPRequired(), because the NLP is now always constructed if nonlinearities
6870 are present.
6871 - SCIPgetNLP() has been removed and NLP-methods from pub_nlp.h have been moved to scip.h, which resulted in some renamings, too.
6872 - renamed SCIPexprtreeEvalSol() to SCIPevalExprtreeSol() and now located in scip.h.
6873 - renamed SCIPexprtreeEvalIntLocalBounds() to SCIPevalExprtreeLocalBounds() and now located in scip.h.
6874 - renamed SCIPexprtreeEvalIntGlobalBounds() to SCIPevalExprtreeGlobalBounds() and now located in scip.h.
6875 - The functions SCIPnlpiGetSolution() and SCIPnlpiSetInitialGuess() got additional arguments to get/set dual values.
6876 - The method SCIPgetNLPI() got a new parameter `nlpiproblem`, which is a pointer to store the NLP solver interface problem.
6877
6878- Timing:
6879 - SCIPincludeProp() got additional parameters to set the timing mask of the propagator and the new callbacks and parameters
6880 related to calling the propagator in presolving.
6881 - SCIPincludeConshdlr() got additional parameters to set the variable deletion callback function and the timing mask for
6882 propagation.
6883 - removed parameters timelimit and memorylimit from SCIPapplyRens()
6884 - The parameters `timelimit` and `memorylimit` were removed from SCIPapplyRens().
6885
6886- Problem Data:
6887 - The method SCIPcopyProb() got a new parameter `global` to indicate whether the global problem or a local version is copied.
6888
6889- Writing and Parsing Constraints:
6890 - The methods SCIPwriteVarName(), SCIPwriteVarsList(), and SCIPwriteVarsLinearsum() got a new boolean parameter `type`
6891 that indicates whether the variable type should be written or not.
6892 - The methods SCIPparseVarName() and SCIPparseVarsList() got a new output parameter `endptr` that is filled with the position
6893 where the parsing stopped.
6894 - The method SCIPwriteVarsList() got additionally a new parameter `delimiter` that defines the character which is used for delimitation.
6895
6896- Variables:
6897 - SCIPmarkDoNotMultaggrVar()/SCIPvarMarkDoNotMultaggr() now allow to mark negated and aggregated variables
6898 - SCIPgetVarCopy() got a new parameter `success` that will be FALSE if method is called after problem creation stage and no hash map is
6899 given or no image for the given variable is contained in the given hash map.
6900 - SCIPchgVarType() got an extra boolean parameter to store if infeasibility is recognized while upgrading a variable from continuous
6901 type to an integer type.
6902 - SCIPdelVar() got a new parameter `deleted`, which stores whether the variable was successfully marked to be deleted.
6903
6904### New API functions
6905
6906- information about the quality of the solution of an LP (currently the condition number of the basis matrix) can now be:
6907 + requested from the LPI (currently only available for CPLEX): methods SCIPlpiGetRealSolQuality() and
6908 + SCIPprintLPSolutionQuality() command display lpsolquality in interactive shell display column lpcond to show
6909 + estimate on condition number, if available
6910- SCIPround() and SCIPfeasRound() to round to nearest integer
6911- SCIPsortRealRealIntInt() and corresponding sorting/inserting/deleting methods in pub_misc.h and necessary defines in misc.c
6912- SCIPsortRealIntLong(), SCIPsortPtrPtrRealInt() and corresponding sorting/inserting/deleting methods in
6913 pub_misc.h and necessary defines in misc.c
6914- SCIPcomputeLPRelIntPoint() to compute relative interior point of the current LP
6915- SCIPstartSolvingTime() and SCIPstopSolvingTime() which can be used to start or stop the solving time clock
6916- SCIPstrToRealValue() and SCIPstrCopySection() in pub_misc.h; these methods can be used to convert a string
6917 into a `SCIP_Real` value and to copy a substring.
6918- SCIPgetBinvarRepresentatives() which gets binary variables that are equal to some given binary variables,
6919 and which are either active, fixed, or multi-aggregated, or the negated variables of active, fixed, or multi-aggregated variables
6920- SCIPhasPrimalRay() and SCIPgetPrimalRayVal() that return whether a primal ray is stored and which value a
6921 given variable has in the primal ray, respectively
6922- SCIPsetConsModifiable()
6923- SCIPsetParam() which is a generic parameter setter method, independent of the parameter type
6924- SCIPpropInitpre(), SCIPpropExitpre(), SCIPpropPresol() which initializes, exists and executes the presolving phase
6925- SCIProwGetAge() to access the age of a row (pub_lp.h/lp.c)
6926- SCIPsolGetOrigObj() in pub_sol.h which returns for a solution in the original problem space the objective value
6927- SCIPretransformSol() in scip.h that allows to retransform a solution to the original space
6928- SCIPlpiClearState() to LP interfaces for clearing basis information in the LP solver
6929- SCIPgetSubscipDepth() to access the depth of the current SCIP as a copied subproblem
6930- SCIPdebugAddSolVal() and SCIPdebugGetSolVal() to add/get values to/from a debug solution
6931- SCIPsepastoreRemoveInefficaciousCuts() to remove non-efficious cuts from the separation storage
6932
6933- Nodes:
6934 - SCIPnodeGetParent() to get parent node of a node
6935 - SCIPnodesSharePath() in pub_tree.h that determines whether two nodes are on the same leaf-root path
6936 - SCIPnodesGetCommonAncestor() in pub_tree.h that finds the common ancestor node for two given nodes
6937
6938- Read and Write:
6939 - SCIPgetReadingTime() which returns the time for reading in seconds
6940 - SCIPparseVarsLinearsum(), SCIPparseVarsPolynomial() and SCIPwriteVarsPolynomial() and for writing and
6941 parsing polynomials in constraint handler writing/parsing methods
6942
6943- Memory:
6944 - SCIPcreateMesshdlrPThreads() and SCIPfreeMesshdlrPThreads() for allocating and deleting necessary memory
6945 for message handlers for parallel pthread version
6946 - SCIPallocClearMemoryArray() and BMSallocClearMemoryArray() for allocating cleared memory arrays in scip.h and memory.h
6947
6948- Intervals:
6949 - SCIPintervalPowerScalarInverse() to solve an equation y = x^p for given bounds on y and scalar exponent p
6950 - SCIPintervalQuadBivar() to compute tight bounds on a bivariate quadratic form
6951 - SCIPintervalSolveBivariateQuadExpressionAllScalar() to compute tight bounds on the solutions of a bivariate quadratic equation
6952
6953- Variables:
6954 - SCIPcomputeVarCurrent{L,U}b{Local,Global}() to compute local or global lower or upper bounds of a
6955 multiaggregated variable from the bounds of the aggregation variables
6956 - SCIPbranchVarValNary() for n-ary variable branching
6957 - SCIPgetNegatedVars() which returns all negated variables for a given array of variables, if the negated
6958 variables are not existing yet, they will be created
6959 - SCIPgetNTotalVars() that returns the total number of created vars, icluding variables that were deleted in the meantime
6960 - SCIPvarGetHashkey(), SCIPvarIsHashkeyEq(), SCIPvarGetHashkeyVal() in pub_var.h which can be used for `SCIP_HASHTABLE` of variables
6961 - SCIPvarGetNBdchgInfosLb() and SCIPvarGetNBdchgInfosUb() in pub_var.h returning the number of lower or upper bound changes on the active path
6962 - SCIPvarGetBdchgInfoLb() and SCIPvarGetBdchgInfoUb() returning the bound change information at the given position
6963 - SCIPvarMarkDeletable() to mark a variable to be deletable completely from the problem (for
6964 branch-and-price); can only be called before the variable is added to the problem
6965 - SCIPvarMarkNotDeletable() that marks a variable to be non-deleteable (used within SCIP for forbidding
6966 deletion of variables contained in solution, LP bases, (multi)aggregation, ...)
6967 - SCIPvarIsDeletable() that returns whether a variable is marked to be deletable (each variable is per default non-deletable)
6968
6969- NLP:
6970 - SCIPgetNLPVarsNonlinearity() to get for each variable in the NLP the number of NLP rows in which this variable appears in a nonlinear way
6971 - SCIPnlrowGetDualsol(), SCIPgetNLPVarsLbDualsol(), SCIPgetNLPVarsUbDualsol() to retrieve dual values from an NLP solution
6972 - SCIPgetNLPFracVars() to get the fractional variables in an NLP solution
6973
6974- Propagator:
6975 - SCIPpropSetPresolPriority() which changes the presolving priority of a given propagator
1.17.0