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:

4.9

Author:

Radoslaw Szymanek

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	debugAll It specifies if the debugging information is printed.
MDD	mdd It specifies a multiple value decision diagram used by this constraint.

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
ExtensionalSupportMDD(IntVar[] vars, int[][] table) It constructs extensional support constraint.
ExtensionalSupportMDD(MDD diagram) It creates an extensional constraint.

Method Summary

Modifier and Type	Method and Description
void	consistency(Store s) 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.
boolean	satisfied() It checks if the constraint is satisfied.
boolean	seekSupport(int nodeId, int level) It checks if the node at a given level of MDD has a support.
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, queueVariable, 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

Field Detail

debugAll

public static final boolean debugAll

It specifies if the debugging information is printed.

See Also:

Constant Field Values

mdd

public MDD mdd

It specifies a multiple value decision diagram used by this constraint.

Constructor Detail

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 Detail

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