A bit-wise epistasis measure for binary search spaces

Abstract

The epistatic variance has been introduced by Davidor as a tool for the evaluation of interdependences between genes, thus possibly giving clues about the difficulty of optimizing functions with genetic algorithms (GAs). Despite its theoretical grounding in Walsh function analysis, several studies have shown its weakness as a predictor of GAs results. In this paper, we focus on binary search spaces and propose to measure epistatic effect on the level of individual genes, an approach that we call bit-wise epistasis. We give examples of this measure on several well-known test problems, then we take into account this supplementary information to improve the performances of evolutionary algorithms. We conclude by pointing towards possible extensions of this concept to real size problems.