org.cpsolver.exam.heuristics

Class ExamNeighbourSelection

java.lang.Object

org.cpsolver.ifs.assignment.context.NeighbourSelectionWithContext<Exam,ExamPlacement,ExamNeighbourSelection.Context>

org.cpsolver.exam.heuristics.ExamNeighbourSelection

All Implemented Interfaces:

CanHoldContext, HasAssignmentContext<Exam,ExamPlacement,ExamNeighbourSelection.Context>, NeighbourSelection<Exam,ExamPlacement>, TerminationCondition<Exam,ExamPlacement>

public class ExamNeighbourSelection
extends NeighbourSelectionWithContext<Exam,ExamPlacement,ExamNeighbourSelection.Context>
implements TerminationCondition<Exam,ExamPlacement>

Examination timetabling neighbour selection.

It consists of the following three phases:

• Construction phase (ExamConstruction until all exams are assigned)
• Hill-climbing phase (HillClimber until the given number if idle iterations)
• Simulated annealing phase (SimulatedAnnealing until timeout is reached)
  • Or great deluge phase (when Exam.GreatDeluge is true, GreatDeluge until timeout is reached)
• At the end (when TerminationCondition.canContinue(Solution) is false), the search is finished with one sweep of final phase ( HillClimber until the given number if idle iterations).

Version:

ExamTT 1.3 (Examination Timetabling)
Copyright (C) 2008 - 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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	ExamNeighbourSelection.Context

Field Summary

Fields inherited from class org.cpsolver.ifs.assignment.context.NeighbourSelectionWithContext

iContextOverride

Fields inherited from interface org.cpsolver.ifs.assignment.context.CanHoldContext

sMaxSize

Constructor Summary

Constructors

Constructor and Description
ExamNeighbourSelection(DataProperties properties) Constructor

Method Summary

Modifier and Type	Method and Description
boolean	canContinue(Solution<Exam,ExamPlacement> currentSolution) Termination condition (i.e., has final phase finished)
ExamNeighbourSelection.Context	createAssignmentContext(Assignment<Exam,ExamPlacement> assignment) Create a new assignment context for the given assignment.
void	init(Solver<Exam,ExamPlacement> solver) Initialization
boolean	isFinalPhase() Is final phase
Neighbour<Exam,ExamPlacement>	selectNeighbour(Solution<Exam,ExamPlacement> solution) Neighbour selection.
void	setFinalPhase(Callback finalPhaseFinished) Set final phase

Methods inherited from class org.cpsolver.ifs.assignment.context.NeighbourSelectionWithContext

getAssignmentContextReference, getContext, getContext, hasContextOverride, isSingleContextSolver, setAssignmentContextReference

Methods inherited from class java.lang.Object

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

Constructor Detail

ExamNeighbourSelection

public ExamNeighbourSelection(DataProperties properties)

Constructor

Parameters:

properties - problem properties

Method Detail

init

public void init(Solver<Exam,ExamPlacement> solver)

Initialization

Specified by:

init in interface NeighbourSelection<Exam,ExamPlacement>

Overrides:

init in class NeighbourSelectionWithContext<Exam,ExamPlacement,ExamNeighbourSelection.Context>

Parameters:

solver - current solver

selectNeighbour

public Neighbour<Exam,ExamPlacement> selectNeighbour(Solution<Exam,ExamPlacement> solution)

Neighbour selection. It consists of the following three phases:

• Construction phase (ExamConstruction until all exams are assigned)
• Hill-climbing phase (HillClimber until the given number if idle iterations)
• Simulated annealing phase (SimulatedAnnealing until timeout is reached)

Specified by:

selectNeighbour in interface NeighbourSelection<Exam,ExamPlacement>

Parameters:

solution - given solution

Returns:

a neighbour assignment

setFinalPhase

public void setFinalPhase(Callback finalPhaseFinished)

Set final phase

Parameters:

finalPhaseFinished - to be called when the final phase is finished

isFinalPhase

public boolean isFinalPhase()

Is final phase

Returns:

true if the final phase is upon us

canContinue

public boolean canContinue(Solution<Exam,ExamPlacement> currentSolution)

Termination condition (i.e., has final phase finished)

Specified by:

canContinue in interface TerminationCondition<Exam,ExamPlacement>

Parameters:

currentSolution - current solution

Returns:

true if the solver can continue with the next iteration

createAssignmentContext

public ExamNeighbourSelection.Context createAssignmentContext(Assignment<Exam,ExamPlacement> assignment)

Description copied from interface: HasAssignmentContext

Create a new assignment context for the given assignment. If there are already some variables assigned in the value, the method should make sure that the context is appropriately initialized.

Specified by:

createAssignmentContext in interface HasAssignmentContext<Exam,ExamPlacement,ExamNeighbourSelection.Context>

Parameters:

assignment - an assignment for which there needs to be an assignment context

Returns:

a new instance of the assignment context, filled according to the given assignment