org.jacop.constraints

Class ExtensionalSupportSTR

java.lang.Object

org.jacop.constraints.DecomposedConstraint<Constraint>

org.jacop.constraints.Constraint

org.jacop.constraints.ExtensionalSupportSTR

All Implemented Interfaces:

Stateful, UsesQueueVariable

public class ExtensionalSupportSTR
extends Constraint
implements UsesQueueVariable, Stateful

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:

4.9

Author:

Radoslaw Szymanek

Field Summary

Fields

Modifier and Type	Field and Description
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<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<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.
Map<Var,Integer>	varToIndex It specifies the mapping of the variable into its index.

Fields inherited from class org.jacop.constraints.Constraint

atomicExecution, consistencyPruningEvents, constraintScope, earlyTerminationOK, increaseWeight, numberId, scope, trace

Fields inherited from class org.jacop.constraints.DecomposedConstraint

queueIndex

Constructor Summary

Constructors

Constructor and Description
ExtensionalSupportSTR(IntVar[] list, boolean reinsertBefore, boolean residuesBefore) Deprecated.
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

Modifier and Type	Method and Description
void	consistency(Store store) It is a (most probably incomplete) consistency function which removes the values from variables domains.
int	getDefaultConsistencyPruningEvent()
void	impose(Store store) It imposes the constraint in a given store.
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	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.
void	storeResidue(int previous, int current) It moves the residue to the beginning of the list.
String	toString() It produces a string representation of a constraint state.

Methods inherited from class org.jacop.constraints.Constraint

afc, arguments, cleanAfterFailure, decompose, getConsistencyPruningEvent, getGuideConstraint, getGuideValue, getGuideVariable, grounded, grounded, id, impose, imposeDecomposition, increaseWeight, intArrayToString, long2int, numberArgs, removeConstraint, requiresMonotonicity, setConsistencyPruningEvent, setConstraintScope, setScope, setScope, setScope, setScope, setScope, setWatchedVariableGrounded, supplyGuideFeedback, updateAFC, watchedVariableGrounded

Methods inherited from class org.jacop.constraints.DecomposedConstraint

auxiliaryVariables, checkInput, checkInput, checkInputForDuplication, checkInputForDuplicationSkipSingletons, checkInputForNullness, checkInputForNullness, checkInputForNullness, derivative, getDubletonsSkipSingletons, imposeDecomposition

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jacop.api.Stateful

isStateful

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.

nexts

public int[] nexts

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

headsOfEliminatedTuples

public TimeStamp<Integer> headsOfEliminatedTuples

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

tailsOfEliminatedTuples

public TimeStamp<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 Map<Var,Integer> varToIndex

It specifies the mapping of the variable into its index.

lastAssignedVariablePosition

public int lastAssignedVariablePosition

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

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

Deprecated.

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.

removeLevel

public void removeLevel(int level)

Description copied from interface: Stateful

This function is called in case of the backtrack, so a constraint can clear the queue of changed variables which is no longer valid. This function is called *before* all timestamps, variables, mutablevariables have reverted to their previous value.

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.

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 V)

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.

V - variable which has changed.

toString

public String toString()

Description copied from class: Constraint

It produces a string representation of a constraint state.

Overrides:

toString in class Constraint