Package org.jacop.constraints

Class ExtensionalSupportMDD

java.lang.Object
org.jacop.constraints.DecomposedConstraint<Constraint>
org.jacop.constraints.Constraint
org.jacop.constraints.ExtensionalSupportMDD
All Implemented Interfaces:
SatisfiedPresent
public class ExtensionalSupportMDD extends Constraint implements SatisfiedPresent
Extensional constraint assures that one of the tuples is enforced in the relation.

This implementation uses technique developed/improved by Roland Yap and his student. Paper presented at CP2008. We would like to thank Roland for answering our detailed questions about the implementation. It is a slightly improved version to what was presented at the conference.

This constraint uses a lot of memory, despite using an MDD. However, if the constraint is imposed multiple times (50+) its overall usage of memory maybe advantageous. Always test against STR version.

Version:
4.10

  • Field Details

  • Constructor Details

    • ExtensionalSupportMDD

      public ExtensionalSupportMDD(MDD diagram)
      It creates an extensional constraint.
      Parameters:
      diagram - multiple-valued decision diagram describing allowed tuples.

    • ExtensionalSupportMDD

      public ExtensionalSupportMDD(IntVar[] vars, int[][] table)
      It constructs extensional support constraint. Please note that parameters will be stored internally as references until the impose of the constraint takes place. Changing parameters after constructing the constraint and before its imposition will change the constraint too.
      Parameters:
      vars - the variables in the scope of the constraint.
      table - list of tuples which are allowed.

  • Method Details

    • impose

      public void impose(Store store)
      Description copied from class: Constraint
      It imposes the constraint in a given store.
      Overrides:
      impose in class Constraint
      Parameters:
      store - the constraint store to which the constraint is imposed to.

    • consistency

      public void consistency(Store s)
      Description copied from class: Constraint
      It is a (most probably incomplete) consistency function which removes the values from variables domains. Only values which do not have any support in a solution space are removed.
      Specified by:
      consistency in class Constraint
      Parameters:
      s - constraint store within which the constraint consistency is being checked.

    • seekSupport

      public boolean seekSupport(int nodeId, int level)
      It checks if the node at a given level of MDD has a support.
      Parameters:
      nodeId - the position of the node in the MDD.
      level - number of variable associated with the node.
      Returns:
      true if node is supported by current domains of variables.

    • getDefaultConsistencyPruningEvent

      public int getDefaultConsistencyPruningEvent()
      Specified by:
      getDefaultConsistencyPruningEvent in class Constraint

    • satisfied

      public boolean satisfied()
      Description copied from interface: SatisfiedPresent
      It checks if the constraint is satisfied. It can return false even if constraint is satisfied but not all variables in its scope are grounded. It needs to return true if all variables in its scope are grounded and constraint is satisfied.

      Implementations of this interface for constraints that are not PrimitiveConstraint may require constraint imposition and consistency check as a requirement to work correctly.

      Specified by:
      satisfied in interface SatisfiedPresent
      Returns:
      true if constraint is possible to verify that it is satisfied.

    • toString

      public String toString()
      Description copied from class: Constraint
      It produces a string representation of a constraint state.
      Overrides:
      toString in class Constraint