org.chocosolver.solver.explanations

Class ExplanationEngine

java.lang.Object

org.chocosolver.solver.explanations.ExplanationEngine

All Implemented Interfaces:

Serializable, FilteringMonitor

public class ExplanationEngine
extends Object
implements FilteringMonitor

An Asynchronous, Reverse, Low-Intrusive and Lazy explanation engine Based on "A Lazy explanation engine for Choco3", C.Prud'homme.

Created by cprudhom on 09/12/14. Project: choco.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected IEventStore	eventStore

Constructor Summary

Constructors

Constructor and Description
ExplanationEngine(Solver solver, boolean userFeedback, boolean enablePartialExplanation) Create an explanation engine based on a rule store

Method Summary

Methods

Modifier and Type	Method and Description
void	activePropagator(BoolVar var, Propagator propagator) Explain the activation of a propagator involved in a reified constraint
Explanation	explain(ContradictionException cex) Compute the explanation of the last event from the event store (naturally, the one that leads to a conflict), and return the explanation of the failure, that is, the (sub-)set of decisions and propagators explaining the conflict.
ConflictStrategy	getCstrat() Return the conflict strategy declared
Explanation	getDecisionRefutationExplanation(Decision decision) Get the explanation of a decision refutation
IEventStore	getEventStore()
RuleStore	getRuleStore()
Solver	getSolver()
void	instantiateTo(IntVar var, int val, ICause cause, int oldLB, int oldUB) This is the main reason why we create this class.
boolean	isSaveCauses() Indicate whether or not the clauses are saved in Explanation
void	moveDecisionRefutation(Decision decision, int to) Move a decision explanation from the old index to the new one.
void	removeValue(IntVar var, int val, ICause cause) This is the main explanation why we create this class.
void	setCstrat(ConflictStrategy cstrat) Set the conflict strategy to use
void	storeDecisionExplanation(Decision decision, Explanation explanation) Store a decision refutation, for future reasoning.
void	updateLowerBound(IntVar var, int value, int old, ICause cause) This is the main reason why we create this class.
void	updateUpperBound(IntVar var, int value, int old, ICause cause) This is the main reason why we create this class.

Methods inherited from class java.lang.Object

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

Field Detail

eventStore

protected final IEventStore eventStore

Constructor Detail

ExplanationEngine

public ExplanationEngine(Solver solver,
                 boolean userFeedback,
                 boolean enablePartialExplanation)

Create an explanation engine based on a rule store

Parameters:

solver - a solver

userFeedback - does user require feedback, ie, keep trace of the constraints in conflict ?

enablePartialExplanation - do explanations need to be complete (for DBT or nogood extraction) ?

Method Detail

getCstrat

public ConflictStrategy getCstrat()

Return the conflict strategy declared

setCstrat

public void setCstrat(ConflictStrategy cstrat)

Set the conflict strategy to use

isSaveCauses

public boolean isSaveCauses()

Indicate whether or not the clauses are saved in Explanation

Returns:

if clauses are saved

explain

public Explanation explain(ContradictionException cex)

Compute the explanation of the last event from the event store (naturally, the one that leads to a conflict), and return the explanation of the failure, that is, the (sub-)set of decisions and propagators explaining the conflict.

Returns:

an explanation (set of decisions and propagators).

getRuleStore

public RuleStore getRuleStore()

getEventStore

public IEventStore getEventStore()

getSolver

public Solver getSolver()

getDecisionRefutationExplanation

public Explanation getDecisionRefutationExplanation(Decision decision)

Get the explanation of a decision refutation

Parameters:

decision - a refuted decision

Returns:

the explanation

storeDecisionExplanation

public void storeDecisionExplanation(Decision decision,
                            Explanation explanation)

Store a decision refutation, for future reasoning.

Parameters:

decision - refuted decision

explanation - the explanation of the refutation

moveDecisionRefutation

public void moveDecisionRefutation(Decision decision,
                          int to)

Move a decision explanation from the old index to the new one. Required for DBT only and should be called with care!

Parameters:

decision - a decision

to - the new index

removeValue

public void removeValue(IntVar var,
               int val,
               ICause cause)

This is the main explanation why we create this class. Record operations to execute for explicit call to explanation.

Specified by:

removeValue in interface FilteringMonitor

Parameters:

var - an integer variable

val - a value

cause - a cause

updateLowerBound

public void updateLowerBound(IntVar var,
                    int value,
                    int old,
                    ICause cause)

This is the main reason why we create this class. Record operations to execute for explicit call to explanation.

Specified by:

updateLowerBound in interface FilteringMonitor

Parameters:

var - an integer variable

value - a value

cause - a cause

old - the previous lower bound

updateUpperBound

public void updateUpperBound(IntVar var,
                    int value,
                    int old,
                    ICause cause)

This is the main reason why we create this class. Record operations to execute for explicit call to explanation.

Specified by:

updateUpperBound in interface FilteringMonitor

Parameters:

var - an integer variable

value - a value

cause - a cause

old - the previous upper bound

instantiateTo

public void instantiateTo(IntVar var,
                 int val,
                 ICause cause,
                 int oldLB,
                 int oldUB)

This is the main reason why we create this class. Record operations to execute for explicit call to explanation.

Specified by:

instantiateTo in interface FilteringMonitor

Parameters:

var - an integer variable

val - a value

cause - a cause

oldLB - previous lb

oldUB - previous ub

activePropagator

public void activePropagator(BoolVar var,
                    Propagator propagator)

Description copied from interface: FilteringMonitor

Explain the activation of a propagator involved in a reified constraint

Specified by:

activePropagator in interface FilteringMonitor

Parameters:

var - the reified variable

propagator - the propagator to awake.