org.jacop.constraints

Class ExtensionalSupportVA

java.lang.Object

org.jacop.constraints.DecomposedConstraint<Constraint>

org.jacop.constraints.Constraint

org.jacop.constraints.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:

4.9

Author:

Radoslaw Szymanek

Field Summary

Fields

Modifier and Type	Field and Description
IntVar[]	list It stores variables within this extensional constraint, order does matter.

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
ExtensionalSupportVA(IntVar[] list) Partial constructor which stores variables involved in a constraint but does not get information about tuples yet.
ExtensionalSupportVA(IntVar[] list, int[][] tuples) Constructor stores reference to tuples until imposition, any changes to tuples parameter will be reflected in the constraint behavior.
ExtensionalSupportVA(List<? extends IntVar> variables, int[][] tuples) The constructor does not create local copy of tuples array.

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[]	findFirstAllowed(int varPosition, int value, int[] t) It finds the first allowed tuple from the given tuple.
protected int	findPosition(int value, int[] values)
int	getDefaultConsistencyPruningEvent()
void	impose(Store store) It imposes the constraint in a given store.
void	queueVariable(int level, Var var) This is a function called to indicate which variable in a scope of constraint has changed.
void	removeLevel(int level) It puts back tuples which have lost their support status at the level which is being removed.
int	seekInvalidPosition(int[] t) It gives the position of the variable for which current domain of this variable does not hold the used value.
int[]	seekSupportVA(int varPosition, int value) It seeks support for a given variable-value pair.
int[]	setFirstValid(int varPosition, int value) It computes the first valid tuple for a given variable-value pair.
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.

Constructor Detail

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 Detail

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.

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.