Abstract: |
In his thesis Toussaint calls for a "general project to develop theories on adaptationprocesses that account for the adaptation of representations". The theory developed inthis paper is a contribution to this project. We first define the simple concept of agenotypic theme and define what it means for mutation operators to be theme preservingand theme altering. We use the idea of theme preservation to develop the concept ofsubrepresentation. Then we develop a theory that illuminates the behavior of amutation-only fitness proportional evolutionary algorithm in which mutation preservesgenotypic themes with high probability. Our theory shows that such evolutionaryalgorithms implicitly implement what we call subrepresentation evolvingmultithreaded evolution, i.e. such EAs conduct second-order search over a predeterminedset of representations and exploit promising representations for first order evolutionarysearch. We illuminate subrepresentaiton evolving multithreaded evolution by comparing andcontrasting it with the behavior of island model EAs. Our theory is immediately useful inunderstanding the significance of the low probability with which theme altering type 2mutations are applied to genotypes of the evolutionary systems in Toussaint's thesis. |
