net.sf.cpsolver.ifs.dbt

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

java.lang.Object

net.sf.cpsolver.ifs.extension.Extension<V,T>

net.sf.cpsolver.ifs.extension.MacPropagation<V,T>

net.sf.cpsolver.ifs.dbt.DbtPropagation<V,T>

All Implemented Interfaces:

ModelListener<V,T>, SolverListener<V,T>

public class DbtPropagation<V extends Variable<V,T>,T extends Value<V,T>>
extends MacPropagation<V,T>
implements SolverListener<V,T>

Maintenance of arc consistency in dynamic backtracking.

The difference between MacPropagation and this DBT propagation is that all not-assigned values of an assigned variable are marked as nogood. Also, when a dead end is reached, unassignment or failure takes place.

This IFS solver extension is to be used only in case of dynamic backtracking and it has no parameters.

Version:

IFS 1.2 (Iterative Forward Search)
Copyright (C) 2006 - 2010 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 .

Field Summary

Fields inherited from class net.sf.cpsolver.ifs.extension.MacPropagation

iConstraints, iIteration

Constructor Summary

Constructors

Constructor and Description
DbtPropagation(Solver<V,T> solver, DataProperties properties) Constructor.

Method Summary

Modifier and Type	Method and Description
void	afterAssigned(long iteration, T value) Propagation takes place every time a value is assigned to a variable.
void	afterUnassigned(long iteration, T value) Undo propagation when a value is unassigned.
boolean	neighbourSelected(long iteration, Neighbour<V,T> neighbour) A neighbour was selected
boolean	valueSelected(long iteration, V variable, T value) If no value is selected (because of a dead end), make some unassignments.
boolean	variableSelected(long iteration, V variable) If no variable is selected (all variables are assinged), unassign the last assigned variable.

Methods inherited from class net.sf.cpsolver.ifs.extension.MacPropagation

addConstraint, beforeAssigned, contains, goodValues, init, isGood, noGood, propagate, propagate, propagate, propagate, setGood, setNoGood, undoPropagate

Methods inherited from class net.sf.cpsolver.ifs.extension.Extension

beforeUnassigned, constraintAdded, constraintRemoved, getModel, getProperties, getSolver, isRegistered, register, unregister, useValueExtra, useVariableExtra, variableAdded, variableRemoved

Methods inherited from class java.lang.Object

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

Constructor Detail

DbtPropagation

public DbtPropagation(Solver<V,T> solver,
                      DataProperties properties)

Constructor. No parameter is taken from properties.

Method Detail

afterAssigned

public void afterAssigned(long iteration,
                          T value)

Propagation takes place every time a value is assigned to a variable.

Prints a warning if the value is nogood (should not never happen), sets all other values of the variable to nogood (explanation is the assigned value itself), runs propagation.

Specified by:

afterAssigned in interface ModelListener<V extends Variable<V,T>,T extends Value<V,T>>

Overrides:

afterAssigned in class MacPropagation<V extends Variable<V,T>,T extends Value<V,T>>

Parameters:

iteration - current iteration

value - value to be assigned

See Also:

MacPropagation.propagate(Variable)

afterUnassigned

public void afterUnassigned(long iteration,
                            T value)

Undo propagation when a value is unassigned.

Prints an error if the value is nogood (should not never happen), runs propagation undo.