Special Forms of Evolution

Abstract

In this chapter we discuss special forms of evolution that in some sense deviate from the standard evolutionary algorithms. In particular, we present coevolution and interactive evolution that both work under “external influence”. In coevolution the influence comes from another population, whose members affect the fitness of the main population. In turn, the main population also influences the fitness of the other one; hence the two populations evolve together. In interactive evolution this influence comes from a user who defines the fitness values by subjective preferences. In both of these cases, the fitness that is awarded to a solution may vary. In the first case because the fitness is dependent on the evolutionary state of the second population, and in the second because users often display inconsistencies. We finish this chapter by describing evolutionary approaches to problems where changing evaluation criteria form the very feature defining them: nonstationary optimisation problems.