org.jacop.constraints

Class ExtensionalSupportMDD

java.lang.Object

org.jacop.constraints.DecomposedConstraint

org.jacop.constraints.Constraint

org.jacop.constraints.ExtensionalSupportMDD

public class ExtensionalSupportMDD
extends Constraint

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:

2.3

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.
static 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 org.jacop.constraints.Constraint

atomicExecution, consistencyPruningEvents, earlyTerminationOK, id, increaseWeight, numberArgs, numberId, 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
ArrayList<Var>	arguments() It returns the variables in a scope of the constraint.
void	consistency(Store s) It is a (most probably incomplete) consistency function which removes the values from variables domains.
int	getConsistencyPruningEvent(Var var) It retrieves the pruning event which causes reevaluation of the 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	removeConstraint() It removes the constraint by removing this constraint from all variables.
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

cleanAfterFailure, decompose, getGuideConstraint, getGuideValue, getGuideVariable, id, impose, imposeDecomposition, numberArgs, queueVariable, removeLevel, removeLevelLate, requiresMonotonicity, setConsistencyPruningEvent, supplyGuideFeedback

Methods inherited from class org.jacop.constraints.DecomposedConstraint

auxiliaryVariables, derivative, 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.

xmlAttributes

public static 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.

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.

Specified by:

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.

getConsistencyPruningEvent

public int getConsistencyPruningEvent(Var var)

Description copied from class: Constraint

It retrieves the pruning event which causes reevaluation of the constraint.

Specified by:

getConsistencyPruningEvent in class Constraint

Parameters:

var - variable for which pruning event is retrieved

Returns:

it returns the int code of the pruning event (GROUND, BOUND, ANY, NONE)

arguments

public ArrayList<Var> arguments()

Description copied from class: Constraint

It returns the variables in a scope of the constraint.

Specified by:

arguments in class Constraint

Returns:

variables in a scope of the constraint.

increaseWeight

public void increaseWeight()

Description copied from class: Constraint

It increases the weight of the variables in the constraint scope.

Specified by:

increaseWeight in class Constraint

removeConstraint

public void removeConstraint()

Description copied from class: Constraint

It removes the constraint by removing this constraint from all variables.

Specified by:

removeConstraint in class Constraint

satisfied

public boolean satisfied()

Description copied from class: Constraint

It checks if the constraint is satisfied. If this function is incorrectly implemented a constraint may not be satisfied in a solution.

Specified by:

satisfied in class Constraint

Returns:

true if the constraint is for certain satisfied, false otherwise.

toString

public String toString()

Description copied from class: Constraint

It produces a string representation of a constraint state.

Specified by:

toString in class Constraint