Module org.chocosolver
Class PropAtMostNValues_BC
- java.lang.Object
-
- org.chocosolver.solver.constraints.Propagator<IntVar>
-
- org.chocosolver.solver.constraints.nary.nvalue.PropAtMostNValues_BC
-
- All Implemented Interfaces:
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
-
-
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 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)
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
getPropagationConditions(int vIdx)
Returns the specific mask indicating the variable events on which thisPropagator
object can react.
A mask is a bitwise OR operations overIEventType
this can react on.ESat
isEntailed()
Check wetherthis
is entailed according to the current state of its internal structure.void
propagate(int evtmask)
Call the main filtering algorithm to apply to theDomain
of theVariable
objects.-
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, getVar, getVars, getVIndice, getVIndices, hashCode, isActive, isCompletelyInstantiated, isPassive, isReified, isReifiedAndSilent, isScheduled, isStateLess, linkVariables, propagate, reactToFineEvent, reifiedWith, setActive, setActive0, setPassive, setPosition, setReifiedSilent, setReifiedTrue, setVIndices, toString, unlinkVariables, unschedule
-
-
-
-
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 variablesnValues
- 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 theDomain
of theVariable
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 classPropagator<IntVar>
- Parameters:
evtmask
- type of propagation eventthis
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
Returns the specific mask indicating the variable events on which thisPropagator
object can react.
A mask is a bitwise OR operations overIEventType
this can react on. For example, consider a propagator that can deduce filtering based on the lower bound of the integer variable X. Then, for this variable, the mask should be equal to :int mask = IntEventType.INCLOW.getMask() | IntEventType.INSTANTIATE.getMask();
or, in a more convenient way:int mask = IntEvtType.combine(IntEventType.INCLOW,IntEventType.INSTANTIATE);
That indicates the following behavior:- if X is instantiated, this propagator will be executed,
- if the lower bound of X is modified, this propagator will be executed,
- if the lower bound of X is removed, the event is promoted from REMOVE to INCLOW and this propagator will NOT be executed,
- otherwise, this propagator will NOT be executed
IntEventType.VOID
which states that this propagator should not be aware of modifications applied to the variable in position vIdx.- Overrides:
getPropagationConditions
in classPropagator<IntVar>
- Parameters:
vIdx
- index of the variable within the propagator- Returns:
- an int composed of
REMOVE
and/orINSTANTIATE
and/orDECUPP
and/orINCLOW
-
isEntailed
public ESat isEntailed()
Description copied from class:Propagator
Check wetherthis
is entailed according to the current state of its internal structure. At least, should check the satisfaction ofthis
(when all is instantiated).- Specified by:
isEntailed
in classPropagator<IntVar>
- Returns:
- ESat.TRUE if entailed, ESat.FALSE if not entailed, ESat.UNDEFINED if unknown
-
-