Module org.chocosolver

Package org.chocosolver.solver.search.loop.lns.neighbors

Class PropagationGuidedNeighborhood

java.lang.Object

org.chocosolver.solver.search.loop.lns.neighbors.IntNeighbor

org.chocosolver.solver.search.loop.lns.neighbors.PropagationGuidedNeighborhood

All Implemented Interfaces:

ICause, INeighbor

Direct Known Subclasses:

ReversePropagationGuidedNeighborhood

public class PropagationGuidedNeighborhood
extends IntNeighbor

A Propagation Guided LNS

Based on "Propagation Guided Large Neighborhood Search", Perron et al. CP2004.

Since:

08/04/13

Author:

Charles Prud'homme

Field Summary

Fields

Modifier and Type	Field	Description
protected int[]	all	Store the modified variables
protected int[]	dsize	Domain size of each variable in IntNeighbor.variables
protected BitSet	fragment	Indicate which variables are selected in a fragment
protected Model	mModel	Reference to the model
protected int	n	Number of variables
protected Random	rd	For randomness

Fields inherited from class org.chocosolver.solver.search.loop.lns.neighbors.IntNeighbor

values, variables

Constructor Summary

Constructors

Constructor	Description
PropagationGuidedNeighborhood(IntVar[] vars, int fgmtSize, int listSize, long seed)	Create a propagation-guided neighbor for LNS

Method Summary

Modifier and Type	Method	Description
void	fixSomeVariables()	Freezes some variables in order to have a fast computation.
void	init()	Initialize this neighbor
void	restrictLess()	Use less restriction at the beginning of a LNS run in order to get better solutions Called when no solution was found during a LNS run (trapped into a local optimum)
protected void	update()	Create the fragment

Methods inherited from class org.chocosolver.solver.search.loop.lns.neighbors.IntNeighbor

forEachIntVar, freeze, loadFromSolution, recordSolution

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.chocosolver.solver.ICause

explain

Methods inherited from interface org.chocosolver.solver.search.loop.lns.neighbors.INeighbor

isSearchComplete

Field Detail

n

protected final int n

Number of variables

dsize

protected int[] dsize

Domain size of each variable in IntNeighbor.variables

rd

protected Random rd

For randomness

all

protected int[] all

Store the modified variables

fragment

protected BitSet fragment

Indicate which variables are selected in a fragment

mModel

protected Model mModel

Reference to the model

Constructor Detail

PropagationGuidedNeighborhood

public PropagationGuidedNeighborhood(IntVar[] vars,
                                     int fgmtSize,
                                     int listSize,
                                     long seed)

Create a propagation-guided neighbor for LNS

Parameters:

vars - set of variables to consider

fgmtSize - initial size of the fragment

listSize - number of modified variable to store while propagating

seed - for randomness

Method Detail

fixSomeVariables

public void fixSomeVariables()
                      throws ContradictionException

Description copied from interface: INeighbor

Freezes some variables in order to have a fast computation. The fixed variables are declared as decisions in the decision path.

Throws:

ContradictionException

update

protected void update()
               throws ContradictionException

Create the fragment

Throws:

ContradictionException - if the fragment is trivially infeasible

restrictLess

public void restrictLess()

Description copied from interface: INeighbor

Use less restriction at the beginning of a LNS run in order to get better solutions Called when no solution was found during a LNS run (trapped into a local optimum)

init

public void init()

Description copied from interface: INeighbor

Initialize this neighbor