Quantitative analysis of locally geometric semantic crossover

Abstract

We investigate the properties of locally geometric semantic crossover (LGX), a genetic programming search operator that is approximately semantically geometric on the level of homologous code fragments. For a pair of corresponding loci in the parents, LGX finds a semantically intermediate procedure from a library prepared prior to evolutionary run, and creates an offspring by using such procedure as replacement code. LGX proves superior when compared to standard subtree crossover and other control methods in terms of search convergence, test-set performance, and time required to find a high-quality solution. This paper focuses in particular the impact of homology and program semantic on LGX performance. © 2012 Springer-Verlag.