Package org.jacop.jasat.modules

Class HeuristicRestartModule

java.lang.Object

org.jacop.jasat.modules.HeuristicRestartModule

All Implemented Interfaces:

SolverComponent, BackjumpListener, ConflictListener

public final class HeuristicRestartModule
extends java.lang.Object
implements ConflictListener, BackjumpListener

A module that indicates if a restart would be useful now. Currently based on number of conflicts since last restart. Each restart makes the next restart twice harder to reach.

Version:

4.8

Field Summary

Fields

Modifier and Type	Field	Description
private long	conflictCount
boolean	shouldRestart
private long	threshold
private double	THRESHOLD_INCREASE_RATE

Constructor Summary

Constructors

Constructor	Description
HeuristicRestartModule()

Method Summary

Modifier and Type	Method	Description
void	initialize(Core core)	initializes the component with the given solver.
void	onBackjump(int oldLevel, int newLevel)	Called when the solver backtracks.
void	onConflict(MapClause clause, int level)	called when a conflict occurs
void	onRestart(int oldLevel)	called when the solver restarts.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

shouldRestart

public boolean shouldRestart

conflictCount

private long conflictCount

threshold

private long threshold

THRESHOLD_INCREASE_RATE

private double THRESHOLD_INCREASE_RATE

Constructor Detail

HeuristicRestartModule

public HeuristicRestartModule()

Method Detail

onConflict

public void onConflict(MapClause clause,
                       int level)

Description copied from interface: ConflictListener

called when a conflict occurs

Specified by:

onConflict in interface ConflictListener

Parameters:

clause - the conflict (unsatisfiable) clause

level - the level at which the conflict occurred

onBackjump

public void onBackjump(int oldLevel,
                       int newLevel)

Description copied from interface: BackjumpListener

Called when the solver backtracks. It will also be called when the solver restarts.

components that want to be warned about backjumps should put themselves in Core.backjumpModules.

Specified by:

onBackjump in interface BackjumpListener

Parameters:

oldLevel - the level at which the solver was before backtracking

newLevel - the level to which the solver backtracks

onRestart

public void onRestart(int oldLevel)

Description copied from interface: BackjumpListener

called when the solver restarts.

components that want to be warned about restarts should put themselves in Core.restartModules.

Specified by:

onRestart in interface BackjumpListener

Parameters:

oldLevel - the level at which the solver was before restarting

initialize

public void initialize(Core core)

Description copied from interface: SolverComponent

initializes the component with the given solver. May be called only once. This method must register the component to the solver for the run.

Specified by:

initialize in interface SolverComponent

Parameters:

core - core component to initialize