org.chocosolver.solver.constraints.nary.nValue

Class PropAtMostNValues_BC

java.lang.Object

org.chocosolver.solver.constraints.Propagator<IntVar>

org.chocosolver.solver.constraints.nary.nValue.PropAtMostNValues_BC

All Implemented Interfaces:

Serializable, Comparable<Propagator>, ICause, Identity

public class PropAtMostNValues_BC
extends Propagator<IntVar>

Propagator for the atMostNValues constraint The number of distinct values in the set of variables vars is at most equal to nValues Performs Bound Consistency in O(n+d) with n = |vars| d = maxValue - minValue (from initial domains)

=> very appropriate when d <= n It is indeed much better than the usual time complexity of O(n.log(n)) => not appropriate when d >> n (you should encode another data structure and a quick sort algorithm)

!redundant propagator!

Author:

Jean-Guillaume Fages

See Also:

Serialized Form

Field Summary

Fields inherited from class org.chocosolver.solver.constraints.Propagator

aCause, ACTIVE, constraint, LOGGER, NEW, PASSIVE, priority, reactToFineEvt, REIFIED, solver, vars

Constructor Summary

Constructors

Constructor and Description

PropAtMostNValues_BC(IntVar[] variables, IntVar nValues) The number of distinct values in vars is at most nValues Performs Bound Consistency in O(n+d) with n = |vars| d = maxValue - minValue (from initial domains) => very appropriate when d <= n It is indeed much better than the usual time complexity of O(n.log(n)) => not appropriate when d >> n (you should encode another data structure and a quick sort algorithm)

Method Summary

Methods

Modifier and Type	Method and Description
void	duplicate(Solver solver, gnu.trove.map.hash.THashMap<Object,Object> identitymap) Duplicate the current propagator.
int	getPropagationConditions(int vIdx) Return the specific mask indicating the variable events on which this Propagator object can react.
ESat	isEntailed() Check wether this is entailed according to the current state of its internal structure.
void	propagate(int evtmask) Call the main filtering algorithm to apply to the Domain of the Variable objects.

Methods inherited from class org.chocosolver.solver.constraints.Propagator

addVariable, advise, arity, compareTo, contradiction, decNbPendingEvt, defineIn, dynPriority, flushPendingEvt, forcePropagate, getConstraint, getId, getNbPendingEvt, getNbVars, getPriority, getSolver, getVar, getVars, getVIndices, hashCode, incNbPendingEvt, isActive, isCompletelyInstantiated, isPassive, isReifiedAndSilent, isStateLess, propagate, reactToFineEvent, setActive, setPassive, setReifiedSilent, setReifiedTrue, setVIndices, toString, why

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

PropAtMostNValues_BC

public PropAtMostNValues_BC(IntVar[] variables,
                    IntVar nValues)

The number of distinct values in vars is at most nValues Performs Bound Consistency in O(n+d) with n = |vars| d = maxValue - minValue (from initial domains)

=> very appropriate when d <= n It is indeed much better than the usual time complexity of O(n.log(n)) => not appropriate when d >> n (you should encode another data structure and a quick sort algorithm)

Parameters:

variables - array of integer variables

nValues - integer variable

Method Detail

propagate

public void propagate(int evtmask)
               throws ContradictionException

Description copied from class: Propagator

Call the main filtering algorithm to apply to the Domain of the Variable objects. It considers the current state of this objects to remove some values from domains and/or instantiate some variables. Calling this method is done from 2 (and only 2) steps:
- at the initial propagation step,
- when involved in a reified constraint.
It should initialized the internal data structure and apply filtering algorithm from scratch.

Specified by:

propagate in class Propagator<IntVar>

Parameters:

evtmask - type of propagation event this must consider.

Throws:

ContradictionException - when a contradiction occurs, like domain wipe out or other incoherencies.

getPropagationConditions

public int getPropagationConditions(int vIdx)

Description copied from class: Propagator

Return the specific mask indicating the variable events on which this Propagator object can react.
Checks are made applying bitwise AND between the mask and the event. Reacts to any kind of event by default.

Overrides:

getPropagationConditions in class Propagator<IntVar>

Parameters:

vIdx - index of the variable within the propagator

Returns:

int composed of REMOVE and/or INSTANTIATE and/or DECUPP and/or INCLOW

isEntailed

public ESat isEntailed()

Description copied from class: Propagator

Check wether this is entailed according to the current state of its internal structure. At least, should check the satisfaction of this (when all is instantiated).

Specified by:

isEntailed in class Propagator<IntVar>

Returns:

ESat.TRUE if entailed, ESat.FALSE if not entailed, ESat.UNDEFINED if unknown

duplicate

public void duplicate(Solver solver,
             gnu.trove.map.hash.THashMap<Object,Object> identitymap)

Description copied from class: Propagator

Duplicate the current propagator. A restriction is that the resolution process should have not begun yet. That's why state of the propagator may not be duplicated.

Overrides:

duplicate in class Propagator<IntVar>

Parameters:

solver - the target solver

identitymap - a map to ensure uniqueness of objects