Class ExtensionalSupportVA

All Implemented Interfaces:
Stateful, UsesQueueVariable

public class ExtensionalSupportVA extends Constraint implements UsesQueueVariable, Stateful
Extensional constraint assures that one of the tuples is enforced in the relation.

This implementation tries to balance the usage of memory versus time efficiency.

Version:
4.8
  • Field Details

    • debugAll

      static final boolean debugAll
      See Also:
    • debugPruning

      static final boolean debugPruning
      See Also:
    • idNumber

      static AtomicInteger idNumber
      It specifies the id of the constraint.
    • firstConsistencyCheck

      boolean firstConsistencyCheck
    • levelOfFirstConsistencyCheck

      int levelOfFirstConsistencyCheck
    • tuples

      int[][][][] tuples
      It represents tuples which are supports for each of the variables. The first index denotes variable index. The second index denotes value index. The third index denotes tuple.
    • tuplesFromConstructor

      private int[][] tuplesFromConstructor
    • values

      int[][] values
      It represents values which are supported for a variable.
    • variableQueue

      LinkedHashSet<IntVar> variableQueue
    • list

      public IntVar[] list
      It stores variables within this extensional constraint, order does matter.
  • Constructor Details

    • ExtensionalSupportVA

      public ExtensionalSupportVA(IntVar[] list)
      Partial constructor which stores variables involved in a constraint but does not get information about tuples yet. The tuples must set separately.
      Parameters:
      list - list of variables for the constraint
    • ExtensionalSupportVA

      public ExtensionalSupportVA(List<? extends IntVar> variables, int[][] tuples)
      The constructor does not create local copy of tuples array. Any changes to this array will reflect on constraint behavior. Most probably incorrect as other data structures will not change accordingly.
      Parameters:
      variables - the constraint scope.
      tuples - the tuples which are supports for the constraint.
    • ExtensionalSupportVA

      public ExtensionalSupportVA(IntVar[] list, int[][] tuples)
      Constructor stores reference to tuples until imposition, any changes to tuples parameter will be reflected in the constraint behavior. Changes to tuples should not performed under any circumstances. The tuples array is not copied to save memory and time.
      Parameters:
      list - the constraint scope.
      tuples - the tuples which are supports for the constraint.
  • Method Details

    • removeLevel

      public void removeLevel(int level)
      It puts back tuples which have lost their support status at the level which is being removed.
      Specified by:
      removeLevel in interface Stateful
      Parameters:
      level - the level which is being removed.
    • consistency

      public void consistency(Store store)
      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:
      store - constraint store within which the constraint consistency is being checked.
    • findPosition

      protected int findPosition(int value, int[] values)
    • getDefaultConsistencyPruningEvent

      public int getDefaultConsistencyPruningEvent()
      Specified by:
      getDefaultConsistencyPruningEvent in class Constraint
    • 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.
    • queueVariable

      public void queueVariable(int level, Var var)
      Description copied from class: Constraint
      This is a function called to indicate which variable in a scope of constraint has changed. It also indicates a store level at which the change has occurred.
      Overrides:
      queueVariable in class Constraint
      Parameters:
      level - the level of the store at which the change has occurred.
      var - variable which has changed.
    • smaller

      boolean smaller(int[] tuple1, int[] tuple2)
    • equal

      boolean equal(int[] tuple1, int[] tuple2)
    • toString

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

      public int[] seekSupportVA(int varPosition, int value)
      It seeks support for a given variable-value pair.
      Parameters:
      varPosition - position of the variable for which the support is seek.
      value - value for which the support is seek.
      Returns:
      support tuple.
    • setFirstValid

      public int[] setFirstValid(int varPosition, int value)
      It computes the first valid tuple for a given variable-value pair.
      Parameters:
      varPosition - position of the variable.
      value - value for which the fist valid tuple is seek.
      Returns:
      first valid tuple.
    • findFirstAllowed

      public int[] findFirstAllowed(int varPosition, int value, int[] t)
      It finds the first allowed tuple from the given tuple.
      Parameters:
      varPosition - position of the variable.
      value - value for which first allowed tuple is seek.
      t - tuple from which the search commences.
      Returns:
      first allowed tuple for a given variable-value pair.
    • seekInvalidPosition

      public int seekInvalidPosition(int[] t)
      It gives the position of the variable for which current domain of this variable does not hold the used value. It is variable because of which allowed tuple does not become a support tuple.
      Parameters:
      t - tuple being checked.
      Returns:
      -1 if tuple is both valid and allowed (support), otherwise the position.