net.sf.cpsolver.exam.heuristics
Class ExamHillClimbing

java.lang.Object
  extended by net.sf.cpsolver.exam.heuristics.ExamHillClimbing
All Implemented Interfaces:
NeighbourSelection<Exam,ExamPlacement>, LazyNeighbour.LazyNeighbourAcceptanceCriterion<Exam,ExamPlacement>, SolutionListener<Exam,ExamPlacement>

public class ExamHillClimbing
extends Object
implements NeighbourSelection<Exam,ExamPlacement>, SolutionListener<Exam,ExamPlacement>, LazyNeighbour.LazyNeighbourAcceptanceCriterion<Exam,ExamPlacement>

Hill climber. In each iteration, one of the following three neighbourhoods is selected first

, then a neighbour is generated and it is accepted if its value ExamSimpleNeighbour.value() is below or equal to zero. The search is stopped after a given amount of idle iterations ( can be defined by problem property HillClimber.MaxIdle).

Version:
ExamTT 1.2 (Examination Timetabling)
Copyright (C) 2008 - 2010 Tomas Muller
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/.

Constructor Summary
ExamHillClimbing(DataProperties properties)
          Constructor
ExamHillClimbing(DataProperties properties, String name)
          Constructor
 
Method Summary
 boolean accept(LazyNeighbour<Exam,ExamPlacement> neighbour, double value)
          Accept lazy neighbour
 void bestCleared(Solution<Exam,ExamPlacement> solution)
          Called by the solution when method Solution.clearBest() is called.
 void bestRestored(Solution<Exam,ExamPlacement> solution)
          Called by the solution when method Solution.restoreBest() is called.
 void bestSaved(Solution<Exam,ExamPlacement> solution)
          Memorize the iteration when the last best solution was found.
 void getInfo(Solution<Exam,ExamPlacement> solution, Map<String,String> info)
          Called by the solution when it is asked to produce info table, see Solution.getInfo().
 void getInfo(Solution<Exam,ExamPlacement> solution, Map<String,String> info, Collection<Exam> variables)
          Called by the solution when it is asked to produce info table, see Solution.getInfo().
 void init(Solver<Exam,ExamPlacement> solver)
          Initialization
 Neighbour<Exam,ExamPlacement> selectNeighbour(Solution<Exam,ExamPlacement> solution)
          Select one of the given neighbourhoods randomly, select neighbour, return it if its value is below or equal to zero (continue with the next selection otherwise).
 void solutionUpdated(Solution<Exam,ExamPlacement> solution)
          Called by the solution when it is updated, see Solution.update(double).
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ExamHillClimbing

public ExamHillClimbing(DataProperties properties)
Constructor

Parameters:
properties - problem properties (use HillClimber.MaxIdle to set maximum number of idle iterations)

ExamHillClimbing

public ExamHillClimbing(DataProperties properties,
                        String name)
Constructor

Parameters:
properties - problem properties (use HillClimber.MaxIdle to set maximum number of idle iterations)
Method Detail

init

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

Specified by:
init in interface NeighbourSelection<Exam,ExamPlacement>

selectNeighbour

public Neighbour<Exam,ExamPlacement> selectNeighbour(Solution<Exam,ExamPlacement> solution)
Select one of the given neighbourhoods randomly, select neighbour, return it if its value is below or equal to zero (continue with the next selection otherwise). Return null when the given number of idle iterations is reached.

Specified by:
selectNeighbour in interface NeighbourSelection<Exam,ExamPlacement>
Parameters:
solution - given solution
Returns:
a neighbour assignment

bestSaved

public void bestSaved(Solution<Exam,ExamPlacement> solution)
Memorize the iteration when the last best solution was found.

Specified by:
bestSaved in interface SolutionListener<Exam,ExamPlacement>
Parameters:
solution - source solution

solutionUpdated

public void solutionUpdated(Solution<Exam,ExamPlacement> solution)
Description copied from interface: SolutionListener
Called by the solution when it is updated, see Solution.update(double).

Specified by:
solutionUpdated in interface SolutionListener<Exam,ExamPlacement>
Parameters:
solution - source solution

getInfo

public void getInfo(Solution<Exam,ExamPlacement> solution,
                    Map<String,String> info)
Description copied from interface: SolutionListener
Called by the solution when it is asked to produce info table, see Solution.getInfo(). A listener can also add some its info into this table.

Specified by:
getInfo in interface SolutionListener<Exam,ExamPlacement>
Parameters:
solution - source solution
info - produced info table

getInfo

public void getInfo(Solution<Exam,ExamPlacement> solution,
                    Map<String,String> info,
                    Collection<Exam> variables)
Description copied from interface: SolutionListener
Called by the solution when it is asked to produce info table, see Solution.getInfo(). A listener can also add some its info into this table.

Specified by:
getInfo in interface SolutionListener<Exam,ExamPlacement>
Parameters:
solution - source solution
info - produced info table
variables - only variables from this set are included

bestCleared

public void bestCleared(Solution<Exam,ExamPlacement> solution)
Description copied from interface: SolutionListener
Called by the solution when method Solution.clearBest() is called.

Specified by:
bestCleared in interface SolutionListener<Exam,ExamPlacement>
Parameters:
solution - source solution

bestRestored

public void bestRestored(Solution<Exam,ExamPlacement> solution)
Description copied from interface: SolutionListener
Called by the solution when method Solution.restoreBest() is called.

Specified by:
bestRestored in interface SolutionListener<Exam,ExamPlacement>
Parameters:
solution - source solution

accept

public boolean accept(LazyNeighbour<Exam,ExamPlacement> neighbour,
                      double value)
Accept lazy neighbour

Specified by:
accept in interface LazyNeighbour.LazyNeighbourAcceptanceCriterion<Exam,ExamPlacement>
Parameters:
neighbour - neighbour that was assigned
value - change in overall solution value
Returns:
true if the neighbour can be accepted (false to undo the assignment)


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