terminations

Introduction

A termination decide when a genetic algorithm should be stopped. GeneticSharp use the GenerationNumberTermination with just one generation as default termination. This mean that the GA will run just one generation when you call the Start method, after this you can increment the expected generation number of the termination and call the method Resume how many times you want.

There are cases where you want to call the Start method in just wait until some condition be reached, this why termination exist.

If you have some special condition to terminate your GA you can implement the ITermination interface or extend the TerminationBase class, but for most of cases you just need to use some of the availables terminations.

var ga = new GeneticAlgorithm(population, fitness, selection, crossover, mutation);
ga.Termination = new GenerationNumberTermination(100);

To use a specific termination, you need to set it on GeneticAlgorithm's Termination property.

Operators

GenerationNumberTermination

ga.termination = new GenerationNumberTermination(100);

The genetic algorithm will be terminate when reach the generation number 100.

TimeEvolvingTermination

ga.termination = new TimeEvolvingTermination(TimeSpan.FromMinutes(5));

The genetic algorithm will be terminate when the evolving exceed the 5 minutes specified.

FitnessStagnationTermination

ga.termination = new FitnessStagnationTermination(100);

The genetic algorithm will be terminate when the best chromosome's fitness has no change in the last 100 generations.

FitnessThresholdTermination

ga.termination = new FitnessThresholdTermination(0.85);

The genetic algorithm will be terminate when the best chromosome reach the expected fitness 0.85.

AndTermination

ga.termination = new AndTermination(
   new GenerationNumberTermination(100), 
   new TimeEvolvingTermination(TimeSpan.FromMinutes(2)));

The genetic algorithm will be terminate when the generation number is greater or equal than 100 and time evolving is greater or equal than 2 minutes.

OrTermination

ga.termination = new OrTermination(
   new GenerationNumberTermination(100), 
   new TimeEvolvingTermination(TimeSpan.FromMinutes(2)));

The genetic algorithm will be terminate when the generation number is greater or equal than 100 or time evolving is greater or equal than 2 minutes.