No Coercion and No Prohibition, a Position Independent Encoding Scheme for Evolutionary Algorithms - The Chorus System

We describe a new encoding system, Chorus, for grammar based Evolutionary Algorithms. This scheme is coarsely based on the manner in nature in which genes produce proteins that regulate the metabolic pathways of the cell. The phenotype is the behaviour of the cells metabolism, which corresponds to the development of the computer program in our case. In this procedure, the actual protein encoded by a gene is the same regardless of the position of the gene within the genome.We show that the Chorus system has a very convenient Regular Expression - type schema notation that can be used to describe the presence of various phenotypes or phenotypic traits. This schema notation is used to demonstrate that massive areas of neutrality can exist in the search landscape, and the system is also shown to be able to dispense with large areas of the search space that are unlikely to contain useful solutions.