net.sf.cpsolver.exam.heuristics
Class ExamGreatDeluge

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

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

Greate deluge. In each iteration, one of the following three neighbourhoods is selected first

, then a neighbour is generated and it is accepted if the value of the new solution is below certain bound. This bound is initialized to the GreatDeluge.UpperBoundRate × value of the best solution ever found. After each iteration, the bound is decreased by GreatDeluge.CoolRate (new bound equals to old bound × GreatDeluge.CoolRate). If the bound gets bellow GreatDeluge.LowerBoundRate × value of the best solution ever found, it is changed back to GreatDeluge.UpperBoundRate × value of the best solution ever found. If there was no improvement found between the bounds, the new bounds are changed to GreatDeluge.UpperBoundRate^2 and GreatDeluge.LowerBoundRate^2, GreatDeluge.UpperBoundRate^3 and GreatDeluge.LowerBoundRate^3, etc. till there is an improvement found.

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
ExamGreatDeluge(DataProperties properties)
          Constructor.
 
Method Summary
 boolean accept(LazyNeighbour<Exam,ExamPlacement> neighbour, double value)
          Accept lazy neighbour
protected  boolean accept(Solution<Exam,ExamPlacement> solution, Neighbour<Exam,ExamPlacement> neighbour)
          Accept 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)
          Update last improving iteration count
 Neighbour<Exam,ExamPlacement> genMove(Solution<Exam,ExamPlacement> solution)
          Generate neighbour -- select neighbourhood randomly, select neighbour
 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().
protected  void incIter(Solution<Exam,ExamPlacement> solution)
          Increment iteration count, update bound
protected  void info(Solution<Exam,ExamPlacement> solution)
          Print some information
 void init(Solver<Exam,ExamPlacement> solver)
          Initialization
 Neighbour<Exam,ExamPlacement> selectNeighbour(Solution<Exam,ExamPlacement> solution)
          A neighbour is generated randomly untill an acceptable one is found.
 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

ExamGreatDeluge

public ExamGreatDeluge(DataProperties properties)
Constructor. Following problem properties are considered:

Parameters:
properties - problem properties
Method Detail

init

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

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

info

protected void info(Solution<Exam,ExamPlacement> solution)
Print some information


genMove

public Neighbour<Exam,ExamPlacement> genMove(Solution<Exam,ExamPlacement> solution)
Generate neighbour -- select neighbourhood randomly, select neighbour


accept

protected boolean accept(Solution<Exam,ExamPlacement> solution,
                         Neighbour<Exam,ExamPlacement> neighbour)
Accept neighbour


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)

incIter

protected void incIter(Solution<Exam,ExamPlacement> solution)
Increment iteration count, update bound


selectNeighbour

public Neighbour<Exam,ExamPlacement> selectNeighbour(Solution<Exam,ExamPlacement> solution)
A neighbour is generated randomly untill an acceptable one is found.

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

bestSaved

public void bestSaved(Solution<Exam,ExamPlacement> solution)
Update last improving iteration count

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


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