org.jacop.constraints

Class Distance

java.lang.Object

org.jacop.constraints.DecomposedConstraint<Constraint>

org.jacop.constraints.Constraint

org.jacop.constraints.PrimitiveConstraint

org.jacop.constraints.Distance

All Implemented Interfaces:

SatisfiedPresent, Stateful, StoreAware

public class Distance
extends PrimitiveConstraint
implements Stateful

Constraint |X - Y| #= Z

Version:

4.9

Author:

Radoslaw Szymanek and Krzysztof Kuchcinski

Field Summary

Fields

Modifier and Type	Field and Description
IntVar	x It specifes variable x in constraint |x-y|=z.
IntVar	y It specifes variable y in constraint |x-y|=z.
IntVar	z It specifes variable z in constraint |x-y|=z.

Fields inherited from class org.jacop.constraints.PrimitiveConstraint

notConsistencyPruningEvents

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
Distance(IntVar x, IntVar y, IntVar z) Distance between x and y |x-y| = z

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()
protected int	getDefaultNestedConsistencyPruningEvent()
protected int	getDefaultNestedNotConsistencyPruningEvent()
protected int	getDefaultNotConsistencyPruningEvent()
void	notConsistency(Store store) It makes pruning in such a way that constraint is notConsistent.
boolean	notSatisfied() It checks if constraint would be always not satisfied.
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This function is called in case of the backtrack, so a constraint can clear the queue of changed variables which is no longer valid.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.
String	toString() It produces a string representation of a constraint state.

Methods inherited from class org.jacop.constraints.PrimitiveConstraint

getNestedPruningEvent, getNotConsistencyPruningEvent, impose, include, setNotConsistencyPruningEvent

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

Methods inherited from interface org.jacop.api.Stateful

isStateful

Field Detail

x

public final IntVar x

It specifes variable x in constraint |x-y|=z.

y

public final IntVar y

It specifes variable y in constraint |x-y|=z.

z

public final IntVar z

It specifes variable z in constraint |x-y|=z.

Constructor Detail

Distance

public Distance(IntVar x,
                IntVar y,
                IntVar z)

Distance between x and y |x-y| = z

Parameters:

x - first parameter

y - second parameter

z - result

Method Detail

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.

getDefaultNestedConsistencyPruningEvent

protected int getDefaultNestedConsistencyPruningEvent()

Overrides:

getDefaultNestedConsistencyPruningEvent in class PrimitiveConstraint

getDefaultNestedNotConsistencyPruningEvent

protected int getDefaultNestedNotConsistencyPruningEvent()

Overrides:

getDefaultNestedNotConsistencyPruningEvent in class PrimitiveConstraint

getDefaultNotConsistencyPruningEvent

protected int getDefaultNotConsistencyPruningEvent()

Specified by:

getDefaultNotConsistencyPruningEvent in class PrimitiveConstraint

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

getDefaultConsistencyPruningEvent

public int getDefaultConsistencyPruningEvent()

Specified by:

getDefaultConsistencyPruningEvent in class Constraint

notSatisfied

public boolean notSatisfied()

Description copied from class: PrimitiveConstraint

It checks if constraint would be always not satisfied.

Specified by:

notSatisfied in class PrimitiveConstraint

Returns:

true if constraint must be notSatisfied, false otherwise.

notConsistency

public void notConsistency(Store store)

Description copied from class: PrimitiveConstraint

It makes pruning in such a way that constraint is notConsistent. It removes values which always belong to a solution.

Specified by:

notConsistency in class PrimitiveConstraint

Parameters:

store - the constraint store in which context the notConsistency technique is evaluated.