ifs.heuristics
Class GeneralVariableSelection

java.lang.Object
  ifs.heuristics.GeneralVariableSelection

All Implemented Interfaces:

VariableSelection

public class GeneralVariableSelection
extends Object
implements VariableSelection

General implementation of variable selection criterion.

In case that all variables are assigned, one of the variables is selected randomly. In case of MPP, the random selection is made among the variables which have not assigned initial values.

When there are unassigned variables, a variable is selected randomly among all unassigned variables (when Variable.RandomSelection is true) or the following roulette wheel selection takes place (MPP):

• one point for a variable with no initial assignment
• 3 * ( 1 + number of conflicts with the initial assignment) for a variable with an initial assignment

If MacPropagation is used and Variable.UnassignWhenNoGood parameter is true, while there is a variable with an empty domain:

• with Variable.UnassignWhenNoGoodRandomWalk probabilty an arbitrary assigned variable is selected
• otherwise, one variable with empty domain is picked, one of its original values is picked and one of the variables from the explanation of that value is then returned. If the explanation is empty, another variable and value is tried (up to ten times).

Parameters:

Parameter	Type	Comment
Variable.RandomSelection	Boolean	if true, an unassigned variable is picked randomly
Variable.UnassignWhenNoGood	Boolean	if true and if MacPropagation is used: if there is a variable with empty domain, assigned variable (which is present in some explanation for a vairable with empty domain) is selected (for reassignment)
Variable.UnassignWhenNoGoodRandomWalk	Double	if Variable.UnassignWhenNoGood is true and if MacPropagation is used: if there is a variable with empty domain, with the given probability an arbitrary assigned variable is selected

Version:

1.0

Author:

Tomáš Müller

See Also:

VariableSelection, Solver

Constructor Summary

GeneralVariableSelection()

GeneralVariableSelection(DataProperties properties)
Constructor

Method Summary

void	init(Solver solver) Initialization
Variable	selectVariable(Solution solution) Variable selection

Methods inherited from class java.lang.Object

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

Constructor Detail

GeneralVariableSelection

public GeneralVariableSelection(DataProperties properties)

Constructor

Parameters:

properties - input configuration

GeneralVariableSelection

public GeneralVariableSelection()

Method Detail

init

public void init(Solver solver)

Initialization

Specified by:

init in interface VariableSelection

selectVariable

public Variable selectVariable(Solution solution)

Variable selection

Specified by:

selectVariable in interface VariableSelection

Parameters:

solution - current solution