ExtensionalSupportSTR (Java Constraint Programming (JaCoP) Specification)

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JaCoP.constraints
Class ExtensionalSupportSTR

java.lang.Object
  JaCoP.constraints.DecomposedConstraint
      JaCoP.constraints.Constraint
          JaCoP.constraints.ExtensionalSupportSTR

public class ExtensionalSupportSTR
extends Constraint
extends Constraint

Extensional constraint assures that one of the tuples is enforced in the relation. This implementation uses technique developed/improved by Christophe Lecoutre. Paper presented at CP2008. We would like to thank him for making his code available, which helped to create our own version of this algorithm.

Version:: 3.1
Author:: Radoslaw Szymanek

Field Summary
`boolean`	`backtrackOccured` It specifies if there was a backtrack and no yet consistency function execution after backtracking.
`int`	`first` Gives the position of the first tuple (in the current list) or -1 if the current list is empty.
`boolean`	`firstConsistencyCheck` It specifies if there was no first consistency check yet.
`int`	`firstResidue` It stores the position of the first residue.
`TimeStamp<java.lang.Integer>`	`headsOfEliminatedTuples` Gives the first position of the eliminated tuple at a given level.
`int`	`last` Gives the position of the last tuple (in the current list) or -1 if the current list is empty.
`int`	`lastAssignedVariablePosition`
`int`	`lastResidue` It stores the position of the last residue.
`IntVar[]`	`list` It stores variables within this extensional constraint, order does matter.
`int`	`nbGlobalValuesToBeSupported` The number of variable-value pairs which need to have support.
`int`	`nbSupportsVariables` It specifies the current number of variables for which it is required to check if their values from the domains are supported.
`int`	`nbValidityVariables` It specifies the number of variables for which validity check within a tuple must be performed.
`int[]`	`nbValuesToBeSupported` The number of variable-value pairs which need to have support per variable.
`int[]`	`nexts` Gives the position of the next tuple wrt the position given in index, or -1.
`boolean`	`reinsertBefore` It specifies if the tuples previously removed are re-inserted at the beginning.
`boolean`	`residuesBefore` It specifies if the residues are moved at the beginning of the list.
`int[]`	`supportsVariablePositions` The positions of the variables for which GAC must be checked.
`TimeStamp<java.lang.Integer>`	`tailsOfEliminatedTuples` Gives the last position of the eliminated tuple at a given level.
`int[][]`	`tuples`
`int[]`	`validityVariablePositions` The positions of the variables for which validity of any tuple must be checked.
`java.util.HashMap<Var,java.lang.Integer>`	`varToIndex` It specifies the mapping of the variable into its index.
`static java.lang.String[]`	`xmlAttributes` It specifies the arguments required to be saved by an XML format as well as the constructor being called to recreate an object from an XML format.

Fields inherited from class JaCoP.constraints.Constraint
`atomicExecution, consistencyPruningEvents, earlyTerminationOK, id, increaseWeight, numberArgs, numberId`

Fields inherited from class JaCoP.constraints.DecomposedConstraint
`queueIndex`

Constructor Summary
`ExtensionalSupportSTR(IntVar[] list, boolean reinsertBefore, boolean residuesBefore)` Partial constructor which stores variables involved in a constraint but does not get information about tuples yet.
`ExtensionalSupportSTR(IntVar[] variables, int[][] tuples)` It creates an extensional constraint.
`ExtensionalSupportSTR(IntVar[] list, int[][] tuples, boolean reinsertBefore, boolean residuesBefore)` It constructs an extensional constraint.

Method Summary
`java.util.ArrayList<Var>`	`arguments()` It returns the variables in a scope of the constraint.
`void`	`consistency(Store store)` It is a (most probably incomplete) consistency function which removes the values from variables domains.
`static void`	`fromXML(ExtensionalSupportSTR object, java.lang.String content)` It updates the specified constraint with the information stored in the string.
`int`	`getConsistencyPruningEvent(Var var)` It retrieves the pruning event which causes reevaluation of the constraint.
`java.lang.String`	`id()` It gives the id string of a constraint.
`void`	`impose(Store store)` It imposes the constraint in a given store.
`void`	`increaseWeight()` It increases the weight of the variables in the constraint scope.
`void`	`queueVariable(int level, Var V)` This is a function called to indicate which variable in a scope of constraint has changed.
`void`	`remove(int previous, int current)` It removes the tuple which is no longer valid.
`void`	`removeConstraint()` It removes the constraint by removing this constraint from all variables.
`void`	`removeLevel(int level)` This function is called in case of the backtrack, so a constraint can clear the queue of changed variables which is no longer valid.
`boolean`	`satisfied()` It checks if the constraint is satisfied.
`void`	`storeResidue(int previous, int current)` It moves the residue to the beginning of the list.
`java.lang.String`	`toString()` It produces a string representation of a constraint state.
`void`	`toXML(javax.xml.transform.sax.TransformerHandler tf)` It writes the content of this object as the content of XML element so later it can be used to restore the object from XML.

Methods inherited from class JaCoP.constraints.Constraint
`cleanAfterFailure, decompose, getGuideConstraint, getGuideValue, getGuideVariable, impose, imposeDecomposition, numberArgs, removeLevelLate, requiresMonotonicity, setConsistencyPruningEvent, supplyGuideFeedback`

Methods inherited from class JaCoP.constraints.DecomposedConstraint
`auxiliaryVariables, imposeDecomposition`

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Field Detail

list

public IntVar[] list

It stores variables within this extensional constraint, order does matter.

tuples

public int[][] tuples

first

public int first

Gives the position of the first tuple (in the current list) or -1 if the current list is empty.

last

public int last

Gives the position of the last tuple (in the current list) or -1 if the current list is empty.

public int[] nexts

Gives the position of the next tuple wrt the position given in index, or -1.

headsOfEliminatedTuples

public TimeStamp<java.lang.Integer> headsOfEliminatedTuples

Gives the first position of the eliminated tuple at a given level.

tailsOfEliminatedTuples

public TimeStamp<java.lang.Integer> tailsOfEliminatedTuples

Gives the last position of the eliminated tuple at a given level.

nbGlobalValuesToBeSupported

public int nbGlobalValuesToBeSupported

The number of variable-value pairs which need to have support.

nbValuesToBeSupported

public int[] nbValuesToBeSupported

The number of variable-value pairs which need to have support per variable.

firstResidue

public int firstResidue

It stores the position of the first residue.

lastResidue

public int lastResidue

It stores the position of the last residue.

nbValidityVariables

public int nbValidityVariables

It specifies the number of variables for which validity check within a tuple must be performed.

validityVariablePositions

public int[] validityVariablePositions

The positions of the variables for which validity of any tuple must be checked.

nbSupportsVariables

public int nbSupportsVariables

It specifies the current number of variables for which it is required to check if their values from the domains are supported.

supportsVariablePositions

public int[] supportsVariablePositions

The positions of the variables for which GAC must be checked. It does not contain variables which were singletons in previous invocation of the consistency function.

varToIndex

public java.util.HashMap<Var,java.lang.Integer> varToIndex

It specifies the mapping of the variable into its index.

lastAssignedVariablePosition

public int lastAssignedVariablePosition

xmlAttributes

public static java.lang.String[] xmlAttributes

It specifies the arguments required to be saved by an XML format as well as the constructor being called to recreate an object from an XML format.

reinsertBefore

public boolean reinsertBefore

It specifies if the tuples previously removed are re-inserted at the beginning.

residuesBefore

public boolean residuesBefore

It specifies if the residues are moved at the beginning of the list.

firstConsistencyCheck

public boolean firstConsistencyCheck

It specifies if there was no first consistency check yet.

backtrackOccured

public boolean backtrackOccured

It specifies if there was a backtrack and no yet consistency function execution after backtracking.

Constructor Detail

ExtensionalSupportSTR

public ExtensionalSupportSTR(IntVar[] list,
                             boolean reinsertBefore,
                             boolean residuesBefore)

Partial constructor which stores variables involved in a constraint but does not get information about tuples yet. The tuples must set separately.

Parameters:: list - the variables in the scope of the constraint.; reinsertBefore - it specifies if the tuples which were removed and are reinstatiated are inserted at the beginning.; residuesBefore - it specifies if the residue tuples are moved to the beginning.

ExtensionalSupportSTR

public ExtensionalSupportSTR(IntVar[] list,
                             int[][] tuples,
                             boolean reinsertBefore,
                             boolean residuesBefore)

It constructs an extensional constraint.

Parameters:: list - the variables in the scope of the constraint.; tuples - the tuples which are supports.; reinsertBefore - it specifies if the tuples which were removed and are reinstatiated are inserted at the beginning.; residuesBefore - it specifies if the residue tuples are moved to the beginning.

ExtensionalSupportSTR

public ExtensionalSupportSTR(IntVar[] variables,
                             int[][] tuples)

It creates an extensional constraint.

Parameters:: variables - the variables in the scope of the constraint.; tuples - the support tuples.

Method Detail

remove

public void remove(int previous,
                   int current)

It removes the tuple which is no longer valid.

Parameters:: previous - the tuple pointing at removed tuple.; current - the removed tuple.

storeResidue

public void storeResidue(int previous,
                         int current)

It moves the residue to the beginning of the list.

Parameters:: previous - the tuple pointing at tuple residue.; current - the residue tuple.