org.chocosolver.solver.objective

Class ObjectiveManager<V extends Variable,N extends Number>

java.lang.Object

org.chocosolver.solver.objective.ObjectiveManager<V,N>

All Implemented Interfaces:

Serializable, ICause

public class ObjectiveManager<V extends Variable,N extends Number>
extends Object
implements ICause

Class to monitor the objective function and avoid exploring "worse" solutions

Since:

Oct. 2012

Author:

Jean-Guillaume Fages

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected N	bestProvedLB
protected N	bestProvedUB
protected V	objective
protected ResolutionPolicy	policy
protected boolean	strict

Constructor Summary

Constructors

Constructor and Description
ObjectiveManager(IntVar objective, ResolutionPolicy policy, boolean strict) Creates an optimization manager for an integer objective function (represented by an IntVar) Enables to cut "worse" solutions
ObjectiveManager(RealVar objective, ResolutionPolicy policy, double precision, boolean strict) Creates an optimization manager for a continuous objective function (represented by a RealVar) Enables to cut "worse" solutions

Method Summary

Methods

Modifier and Type	Method and Description
void	apply(Decision decision) Updates the lower (or upper) bound of the objective variable, considering its best know value.
N	getBestLB()
N	getBestSolutionValue()
N	getBestUB()
protected int	getNbDecimals()
V	getObjective()
ResolutionPolicy	getPolicy()
boolean	isOptimization()
void	postDynamicCut() Prevent the solver from computing worse quality solutions
static ObjectiveManager	SAT()
String	toString()
void	update() Informs the manager that a new solution has been found
void	updateBestLB(N lb) States that lb is a global lower bound on the problem
void	updateBestUB(N ub) States that ub is a global upper bound on the problem
boolean	why(RuleStore ruleStore, IntVar var, IEventType evt, int value) Add new rules to the rule store

Methods inherited from class java.lang.Object

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

Field Detail

policy

protected final ResolutionPolicy policy

strict

protected final boolean strict

objective

protected final V extends Variable objective

bestProvedLB

protected N extends Number bestProvedLB

bestProvedUB

protected N extends Number bestProvedUB

Constructor Detail

ObjectiveManager

public ObjectiveManager(IntVar objective,
                ResolutionPolicy policy,
                boolean strict)

Creates an optimization manager for an integer objective function (represented by an IntVar) Enables to cut "worse" solutions

Parameters:

objective - variable (represent the value of a solution)

policy - SATISFACTION / MINIMIZATION / MAXIMIZATION

strict - Forces to compute strictly better solutions. Enables to enumerate better or equal solutions when set to false.

ObjectiveManager

public ObjectiveManager(RealVar objective,
                ResolutionPolicy policy,
                double precision,
                boolean strict)

Creates an optimization manager for a continuous objective function (represented by a RealVar) Enables to cut "worse" solutions

Parameters:

objective - variable (represent the value of a solution)

policy - SATISFACTION / MINIMIZATION / MAXIMIZATION

precision - precision parameter defining the minimum objective improvement between two solutions (avoids wasting time enumerating a huge set of equivalent solutions)

strict - Forces to compute strictly better solutions. Enables to enumerate better or equal solutions when set to false.

Method Detail

SAT

public static ObjectiveManager SAT()

isOptimization

public boolean isOptimization()

Returns:

true iff the problem is an optimization problem

apply

public void apply(Decision decision)
           throws ContradictionException

Updates the lower (or upper) bound of the objective variable, considering its best know value.

Parameters:

decision - decision to apply

Throws:

ContradictionException - if this application leads to a contradiction @param decision

why

public boolean why(RuleStore ruleStore,
          IntVar var,
          IEventType evt,
          int value)

Description copied from interface: ICause

Add new rules to the rule store

Specified by:

why in interface ICause

Parameters:

ruleStore - the rule store

var - the modified variable

evt - the undergoing event

value - the value (for REMOVE only)

Returns:

true if at least one rule has been added to the rule store

toString

public String toString()

Overrides:

toString in class Object

getNbDecimals

protected int getNbDecimals()

update

public void update()

Informs the manager that a new solution has been found

postDynamicCut

public void postDynamicCut()
                    throws ContradictionException

Prevent the solver from computing worse quality solutions

Throws:

ContradictionException

getBestSolutionValue

public N getBestSolutionValue()

Returns:

the best solution value found so far (returns the initial bound if no solution has been found yet)

updateBestLB

public void updateBestLB(N lb)

States that lb is a global lower bound on the problem

Parameters:

lb - lower bound

updateBestUB

public void updateBestUB(N ub)

States that ub is a global upper bound on the problem

Parameters:

ub - upper bound

getPolicy

public ResolutionPolicy getPolicy()

Returns:

the ResolutionPolicy of the problem

getObjective

public V getObjective()

Returns:

the objective variable

getBestLB

public N getBestLB()

Returns:

the best lower bound computed so far

getBestUB

public N getBestUB()

Returns:

the best upper bound computed so far