Under the Hood of Grammatical Evolution

Grammatical Evolution (GE) is a grammar based GA to generate computer programs which has been shown to be comparable with GP when applied to a diverse array of problems. GE has the distinction that its input is a BNF, which permits it to generate programs in any language, of arbitrary complexity, including loops, multiple line functions etc. Part of the power of GE is that it is closer to natural DNA than GP, and thus can benefit from natural phenomena such as a separation of search and solution spaces through a genotype to phenotype mapping, and a genetic code degeneracy which can give rise to silent mutations(Mutations that have no effect on the phenotype). We have previously shown how runs of GE are competitive with GP, and in this paper we analyse characteristics such as genotypic diversity, and individual genotypic length, in an attempt to shed light on the power of the system. Results indicate that GE can use certain features of the system to its benefit if and when necessary.