org.eclipse.viatra.dse.objectives

Interface IObjective

All Known Implementing Classes:

AlwaysSatisfiedDummyHardObjective, BaseObjective, CompositeObjective, ConstraintsObjective, DepthHardObjective, NeverSatisfiedDummyHardObjective, NoRuleActivationsHardObjective, TrajectoryCostSoftObjective

public interface IObjective

Implementation of this interface represents a single objective of the DSE problem, which can assess a solution (trajectory) in a single number. It has a name and a comparator which orders two solution based on the calculated value.

Objectives can be either hard or soft objectives. Hard objectives can be satisfied or unsatisfied. If all of the hard objectives are satisfied on a single solution, then it is considered to be a valid (or goal) solution.

Certain objectives can have inner state for calculating the fitness value. In this case a new instance is necessary for every new thread, and the createNew method should not return the same instance more than once.

Method Summary

Modifier and Type	Method and Description
IObjective	createNew() Returns an instance of the IObjective.
java.util.Comparator<java.lang.Double>	getComparator() Returns a Comparator which is used to compare fitness (doubles).
java.lang.Double	getFitness(ThreadContext context) Calculates the value of the objective on a given solution (trajectory).
int	getLevel() Gets the level of the objective.
java.lang.String	getName() Returns the name of the objective.
void	init(ThreadContext context) Initializes the objective.
boolean	isHardObjective() Returns true if the objective is a hard objective.
boolean	satisifiesHardObjective(java.lang.Double fitness) Determines if the given fitness value satisfies the hard objective.
void	setComparator(java.util.Comparator<java.lang.Double> comparator) Sets the Comparator which is used to compare fitness (doubles).
void	setLevel(int level) Set the level of the objective.

Method Detail

getName

java.lang.String getName()

Returns the name of the objective.

Returns:

The name of the objective.

setComparator

void setComparator(java.util.Comparator<java.lang.Double> comparator)

Sets the Comparator which is used to compare fitness (doubles). It determines whether the objective is to minimize or maximize (or minimize or maximize a delta from a given number).

Parameters:

comparator - The comparator.

getComparator

java.util.Comparator<java.lang.Double> getComparator()

Returns a Comparator which is used to compare fitness (doubles). It determines whether the objective is to minimize or maximize (or minimize or maximize a delta from a given number).

Returns:

The comparator.

getFitness

java.lang.Double getFitness(ThreadContext context)

Calculates the value of the objective on a given solution (trajectory).

Parameters:

context - The ThreadContext

Returns:

The objective value in double.

init

void init(ThreadContext context)

Initializes the objective. It is called exactly once for every thread starts.

Parameters:

context - The ThreadContext.

createNew

IObjective createNew()

Returns an instance of the IObjective. If it returns the same instance, all the methods has to be thread save as they are called concurrently.

Returns:

An instance of the objective.

isHardObjective

boolean isHardObjective()

Returns true if the objective is a hard objective. In such a case the method satisifiesHardObjective(Double) is called.

Returns:

True if the objective is a hard objective.

See Also:

satisifiesHardObjective(Double), IObjective

satisifiesHardObjective

boolean satisifiesHardObjective(java.lang.Double fitness)

Determines if the given fitness value satisfies the hard objective.

Parameters:

fitness - The fitness value of a solution.

Returns:

True if it satisfies the hard objective or it is a soft constraint.

See Also:

IObjective

setLevel

void setLevel(int level)

Set the level of the objective.

getLevel

int getLevel()

Gets the level of the objective.