org.jamesframework.core.search.algo.tabu

Class FullTabuMemory<SolutionType extends Solution>

java.lang.Object

org.jamesframework.core.search.algo.tabu.FullTabuMemory<SolutionType>

Type Parameters:

SolutionType - solution type of the tabu memory, required to extend Solution; should match with the solution type of the tabu search that uses this memory

All Implemented Interfaces:

TabuMemory<SolutionType>

public class FullTabuMemory<SolutionType extends Solution>
extends Object
implements TabuMemory<SolutionType>

Full tabu memory that stores deeps copies of recently visited solutions and declares a move tabu if applying it to the current solution yields a neighbouring solution which is currently contained in the memory. A full tabu memory has a single parameter controlling the size of the memory, i.e. the number of recently visited solutions which are simultaneously stored. If the size is exceeded, the least recently visited solution is discarded from the memory (FIFO).

Author:

Herman De Beukelaer

Constructor Summary

Constructors

Constructor and Description
FullTabuMemory(int size) Creates a full tabu memory with specified size.

Method Summary

Modifier and Type	Method and Description
void	clear() Clear the tabu memory.
boolean	isTabu(Move<? super SolutionType> move, SolutionType currentSolution) Verifies whether the given move is tabu by applying it to the current solution and checking if the obtained neighbour is currently contained in the tabu memory.
void	registerVisitedSolution(SolutionType visitedSolution, Move<? super SolutionType> appliedMove) A newly visited solution is registered by storing a deep copy of this solution in the full tabu memory.

Methods inherited from class java.lang.Object

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

Constructor Detail

FullTabuMemory

public FullTabuMemory(int size)

Creates a full tabu memory with specified size. This memory stores deep copies of recently visited solutions, where the least recently visited solution is discarded if the memory size is exceeded.

Parameters:

size - memory size (strictly positive)

Throws:

IllegalArgumentException - if size is not strictly positive

Method Detail

isTabu

public boolean isTabu(Move<? super SolutionType> move,
                      SolutionType currentSolution)

Verifies whether the given move is tabu by applying it to the current solution and checking if the obtained neighbour is currently contained in the tabu memory. If not, the move is allowed. Before returning, the move is undone to restore the original state of the current solution.

Specified by:

isTabu in interface TabuMemory<SolutionType extends Solution>

Parameters:

move - move to be applied to the current solution

currentSolution - current solution

Returns:

true if the neighbour obtained by applying the given move to the current solution is currently already contained in the tabu memory

registerVisitedSolution

public void registerVisitedSolution(SolutionType visitedSolution,
                                    Move<? super SolutionType> appliedMove)

A newly visited solution is registered by storing a deep copy of this solution in the full tabu memory.

Specified by:

registerVisitedSolution in interface TabuMemory<SolutionType extends Solution>

Parameters:

visitedSolution - newly visited solution (copied to memory)

appliedMove - applied move (not used here, allowed to be null)

clear

public void clear()

Clear the tabu memory.

Specified by:

clear in interface TabuMemory<SolutionType extends Solution>