org.cpsolver.ifs.heuristics

Class GeneralValueSelection<V extends Variable<V,T>,T extends Value<V,T>>

java.lang.Object

org.cpsolver.ifs.heuristics.GeneralValueSelection<V,T>

Type Parameters:

V - Variable

T - Value

All Implemented Interfaces:

ValueSelection<V,T>

public class GeneralValueSelection<V extends Variable<V,T>,T extends Value<V,T>>
extends Object
implements ValueSelection<V,T>

General implementation of value selection criterion.

Value selection criterion is based on weighted sum of various criteria. It also allows random walk technique and tabu search.
Parameters:

Related Solver Parameters

Parameter	Type	Comment
General.MPP	Boolean	if true, MPP is being solved
Value.MPPLimit	Integer	MPP: limitation of the number of allowed perturbations. If a solution within this limit is gound, it is decreased.
Value.InitialSelectionProb	Double	MPP: probability of selection of the initial value
Value.RandomWalkProb	Double	Random Walk: probability of selection of a value randomly among all the values
Value.Tabu	Integer	Tabu Search: length of the tabu-list
Value.GoodSelectionProb	Double	In case of MacPropagation, with this probability (1.0 means always), the selection is made only among good values (not removed from the domain).

Following weights are used in the weighted sum (computed for all values). The value with the lowest weighted sum is selected. If there are more than one of such values, one of them is selected randomly.

Related Solver Parameters

Parameter	Type	Comment
Value.WeightDeltaInitialAssignments	Double	MPP: Difference in the number of assigned initial values if the value is assigned to the variable (weighted by this Value.WeightDeltaInitialAssignments): -1 if the value is initial, 0 otherwise, increased by the number of initial values assigned to variables with hard conflicts with the value
Value.WeightWeightedConflicts	Double	When ConflictStatistics is used: weighted number of conflicting variables
Value.WeightPotentialConflicts	Double	When ConflictStatistics is used: weighted number of potentially conflicting variables
Value.WeightConflicts	Double	Number of conflicting variables Model.conflictValues(Assignment, Value).
Value.WeightValue	Double	Value Value.toDouble(Assignment)

Version:

IFS 1.3 (Iterative Forward Search)
Copyright (C) 2006 - 2014 Tomáš Müller
muller@unitime.org
http://muller.unitime.org

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not see http://www.gnu.org/licenses.

Author:

Tomáš Müller

See Also:

VariableSelection, Solver

Field Summary

Fields

Modifier and Type	Field and Description
protected ArrayList<T>	iTabu
protected int	iTabuPos
protected int	iTabuSize

Constructor Summary

Constructors

Constructor and Description
GeneralValueSelection()
GeneralValueSelection(DataProperties properties) Constructor

Method Summary

Modifier and Type	Method and Description
void	init(Solver<V,T> solver) Initialization
T	selectValue(Solution<V,T> solution, V selectedVariable) Value selection

Methods inherited from class java.lang.Object

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

Field Detail

iTabuSize

protected int iTabuSize

iTabu

protected ArrayList<T extends Value<V,T>> iTabu

iTabuPos

protected int iTabuPos

Constructor Detail

GeneralValueSelection

public GeneralValueSelection()

GeneralValueSelection

public GeneralValueSelection(DataProperties properties)

Constructor

Parameters:

properties - input configuration

Method Detail

init

public void init(Solver<V,T> solver)

Initialization

Specified by:

init in interface ValueSelection<V extends Variable<V,T>,T extends Value<V,T>>

Parameters:

solver - current solver

selectValue

public T selectValue(Solution<V,T> solution,
                     V selectedVariable)

Value selection

Specified by:

selectValue in interface ValueSelection<V extends Variable<V,T>,T extends Value<V,T>>

Parameters:

solution - current solution

selectedVariable - selected variable

Returns:

selected value (of the given variable)