JaCoP.constraints
Class ExtensionalSupportVA

java.lang.Object
  JaCoP.constraints.DecomposedConstraint
      JaCoP.constraints.Constraint
          JaCoP.constraints.ExtensionalSupportVA

public class ExtensionalSupportVA
extends Constraint

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:

3.1

Author:

Radoslaw Szymanek

Field Summary

static int	idNumber It specifies the id of the constraint.
IntVar[]	list It stores variables within this extensional constraint, order does matter.
static java.lang.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 JaCoP.constraints.Constraint

atomicExecution, consistencyPruningEvents, earlyTerminationOK, id, increaseWeight, numberArgs, numberId

Fields inherited from class JaCoP.constraints.DecomposedConstraint

queueIndex

Constructor Summary

ExtensionalSupportVA(java.util.ArrayList<? extends IntVar> variables, int[][] tuples)
The constructor does not create local copy of tuples array.

ExtensionalSupportVA(IntVar[] list)
Partial constructor which stores variables involved in a constraint but does not get information about tuples yet.

ExtensionalSupportVA(IntVar[] variables, int[][] tuples)
Constructor stores reference to tuples until imposition, any changes to tuples parameter will be reflected in the constraint behavior.

Method Summary

java.util.ArrayList<Var>	arguments() It returns the variables in a scope of the constraint.
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.
static void	fromXML(ExtensionalSupportVA object, java.lang.String content) It updates the specified constraint with the information stored in the string.
int	getConsistencyPruningEvent(Var var) It retrieves the pruning event which causes reevaluation of the constraint.
java.lang.String	id() It gives the id string of a 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	queueVariable(int level, Var var) This is a function called to indicate which variable in a scope of constraint has changed.
void	removeConstraint() It removes the constraint by removing this constraint from all variables.
void	removeLevel(int level) It puts back tuples which have lost their support status at the level which is being removed.
boolean	satisfied() It checks if the constraint is satisfied.
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.
java.lang.String	toString() It produces a string representation of a constraint state.
void	toXML(javax.xml.transform.sax.TransformerHandler tf) It writes the content of this object as the content of XML element so later it can be used to restore the object from XML.

Methods inherited from class JaCoP.constraints.Constraint

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

Methods inherited from class JaCoP.constraints.DecomposedConstraint

auxiliaryVariables, imposeDecomposition

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

idNumber

public static int idNumber

It specifies the id of the constraint.

list

public IntVar[] list

It stores variables within this extensional constraint, order does matter.

xmlAttributes

public static java.lang.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

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 -

ExtensionalSupportVA

public ExtensionalSupportVA(java.util.ArrayList<? 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[] variables,
                            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:

variables - the constraint scope.

tuples - the tuples which are supports for the constraint.

Method Detail

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.

arguments

public java.util.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.

removeLevel

public void removeLevel(int level)

It puts back tuples which have lost their support status at the level which is being removed.

Overrides:

removeLevel in class Constraint

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.

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)

id

public java.lang.String id()

Description copied from class: Constraint

It gives the id string of a constraint.

Specified by:

id in class Constraint

Returns:

string id of the constraint.

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.

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.

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 java.lang.String toString()

Description copied from class: Constraint

It produces a string representation of a constraint state.

Specified by:

toString in class Constraint

toXML

public void toXML(javax.xml.transform.sax.TransformerHandler tf)
           throws org.xml.sax.SAXException

It writes the content of this object as the content of XML element so later it can be used to restore the object from XML. It is done after restoration of the part of the object specified in xmlAttributes.

Parameters:

tf - a place to write the content of the object.

Throws:

org.xml.sax.SAXException

fromXML

public static void fromXML(ExtensionalSupportVA object,
                           java.lang.String content)

It updates the specified constraint with the information stored in the string.

Parameters:

object - the constraint to be updated.

content - the information used for update.

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