Module org.chocosolver

Package org.chocosolver.solver.constraints.nary.nvalue

Class PropAtLeastNValues_AC

java.lang.Object

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

org.chocosolver.solver.constraints.nary.nvalue.PropAtLeastNValues_AC

All Implemented Interfaces:

Comparable<Propagator>, ICause, Identity

public class PropAtLeastNValues_AC
extends Propagator<IntVar>

AtLeastNValues Propagator (similar to SoftAllDiff) The number of distinct values in vars is at least nValues Performs Generalized Arc Consistency based on Maximum Bipartite Matching The worst case time complexity is O(nm) but this is very pessimistic In practice it is more like O(m) where m is the number of variable-value pairs

BEWARE UNSAFE : BUG DETECTED THROUGH DOBBLE(3,4,6)

!redundant propagator!

Author:

Jean-Guillaume Fages

Field Summary

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

ACTIVE, constraint, DEFAULT_EXPL, model, operations, OUTPUT_DEFAULT_EXPL, priority, reactToFineEvt, state, vars

Constructor Summary

Constructors

Constructor	Description
PropAtLeastNValues_AC(IntVar[] variables, int[] vals, IntVar nValues)	AtLeastNValues Propagator (similar to SoftAllDiff) The number of distinct values in vars is at least nValues Performs Generalized Arc Consistency based on Maximum Bipartite Matching The worst case time complexity is O(nm) but this is very pessimistic In practice it is more like O(m) where m is the number of variable-value pairs

Method Summary

Modifier and Type	Method	Description
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.
void	propagate(int varIdx, int mask)	Incremental filtering algorithm defined within the Propagator, called whenever the variable of index idxVarInProp has changed.

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

addVariable, arity, compareTo, defaultExplain, doFinePropagation, doFlush, doSchedule, doScheduleEvent, dynPriority, equals, explain, fails, forcePropagate, forcePropagationOnBacktrack, forEachIntVar, getConstraint, getId, getModel, getNbVars, getPosition, getPriority, getPropagationConditions, getVar, getVars, getVIndice, getVIndices, hashCode, isActive, isCompletelyInstantiated, isPassive, isReified, isReifiedAndSilent, isScheduled, isStateLess, linkVariables, reactToFineEvent, reifiedWith, setActive, setActive0, setPassive, setPosition, setReifiedSilent, setReifiedTrue, setVIndices, toString, unlinkVariables, unschedule

Methods inherited from class java.lang.Object

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

Constructor Detail

PropAtLeastNValues_AC

public PropAtLeastNValues_AC(IntVar[] variables,
                             int[] vals,
                             IntVar nValues)

AtLeastNValues Propagator (similar to SoftAllDiff) The number of distinct values in vars is at least nValues Performs Generalized Arc Consistency based on Maximum Bipartite Matching The worst case time complexity is O(nm) but this is very pessimistic In practice it is more like O(m) where m is the number of variable-value pairs

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.

propagate

public void propagate(int varIdx,
                      int mask)
               throws ContradictionException

Description copied from class: Propagator

Incremental filtering algorithm defined within the Propagator, called whenever the variable of index idxVarInProp has changed. This method calls a CUSTOM_PROPAGATION (coarse-grained) by default.

This method should be overridden if the argument reactToFineEvt is set to true in the constructor. Otherwise, it executes propagate(PropagatorEventType.CUSTOM_PROPAGATION.getStrengthenedMask());

Overrides:

propagate in class Propagator<IntVar>

Parameters:

varIdx - index of the variable var in this

mask - type of event

Throws:

ContradictionException - if a contradiction occurs

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