Package org.moeaframework.problem.misc

Class Schaffer2

java.lang.Object

org.moeaframework.problem.AbstractProblem

org.moeaframework.problem.misc.Schaffer2

All Implemented Interfaces:

AutoCloseable, Problem, AnalyticalProblem

public class Schaffer2
extends AbstractProblem
implements AnalyticalProblem

The Schaffer (2) problem. The Schaffer (2) problem is univariate, with the optimum defined by 1 <= x <= 2 and 4 <= x <= 5.

Properties:

• Disconnected Pareto set
• Disconnected Pareto front

References:

1. Schaffer, J. D. (1984). "Some Experiments in Machine Learning using Vector Evaluated Genetic Algorithms." Ph.D. Thesis, Vanderbilt University, Nashville, USA.
2. Schaffer, J. D. (1985). "Multiple Objective Optimization with Vector Evaluated Genetic Algorithms." Genetic Algorithms and Their Applications: Proceedings of the First International Conference on Genetic Algorithms, pp. 93-100.
3. Van Veldhuizen, D. A (1999). "Multiobjective Evolutionary Algorithms: Classifications, Analyses, and New Innovations." Air Force Institute of Technology, Ph.D. Thesis, Appendix B.

Field Summary

Fields inherited from class org.moeaframework.problem.AbstractProblem

numberOfConstraints, numberOfObjectives, numberOfVariables

Constructor Summary

Constructors

Constructor	Description
Schaffer2()	Constructs the Schaffer (2) problem.

Method Summary

Modifier and Type	Method	Description
void	evaluate(Solution solution)	Evaluates the solution, updating the solution's objectives in place.
Solution	generate()	Returns a randomly-generated solution using the analytical solution to this problem.
Solution	newSolution()	Returns a new solution for this problem.

Methods inherited from class org.moeaframework.problem.AbstractProblem

close, getName, getNumberOfConstraints, getNumberOfObjectives, getNumberOfVariables

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.moeaframework.core.Problem

close, getName, getNumberOfConstraints, getNumberOfObjectives, getNumberOfVariables, isType

Constructor Details

Schaffer2

public Schaffer2()

Constructs the Schaffer (2) problem.

Method Details

evaluate

public void evaluate(Solution solution)

Description copied from interface: Problem

Evaluates the solution, updating the solution's objectives in place. Algorithms must explicitly call this method when appropriate to evaluate new solutions or reevaluate modified solutions.

Specified by:

evaluate in interface Problem

Parameters:

solution - the solution to be evaluated

newSolution

public Solution newSolution()

Description copied from interface: Problem

Returns a new solution for this problem. Implementations must initialize the variables so that the valid range of values is defined, but typically leave the actual value at a default or undefined state.

Specified by:

newSolution in interface Problem

Returns:

a new solution for this problem

generate

public Solution generate()

Description copied from interface: AnalyticalProblem

Returns a randomly-generated solution using the analytical solution to this problem. The exact behavior of this method depends on the implementation, but in general (1) the solutions should be non-dominated and (2) spread uniformly across the Pareto front.

It is not always possible to guarantee these conditions. For example, a discontinuous / disconnected Pareto surface could generate dominated solutions, and a biased problem could result in non-uniform distributions. Therefore, we recommend callers filter solutions through a NondominatedPopulation, in particular one that maintains a spread of solutions.

Furthermore, some implementations may not provide the corresponding decision variables for the solution. These implementations should indicate this by returning a solution with 0 decision variables.

Specified by:

generate in interface AnalyticalProblem

Returns:

a randomly-generated Pareto optimal solution to this problem