When are Building Blocks Useful?

There is still debate about as to how GAs work. Although exact mathematical formulations have been available for quite some time, they have not really led to much progress in terms of giving an intuitive answer to this question. One of the principle reasons for this is that exact formulations have traditionally been written in terms of strings. For a recombinative GA however, Building Block schemata are the most natural description. We make an experimental study in the context of a family of modular fitness landscapes and compare with theoretical results of the infinite population model. We show how the utility of recombination is linked to the nature of the fitness landscape, the more modular the landscape the more useful is recombination, and from that how the nature - length, order, geometry - of what are optimal Building Blocks manifests itself.