First published 2 September 2013
Evolution of G-P mapping in a von Neumann Self-reproducer within Tierra
Declan Baugh, Barry McMullin
John von Neumann first presented his theory of machine self-reproduction in the late 40's (von Neumann, 1948), in which he described a machine capable of performing the logical steps necessary to accommodate self-reproduction. The proposed architecture was comprised of two distinct components, a passive genotype, which acts exclusively as an information storage of a machine description, and an active phenotype which is responsible for all mechanical functionality of the machine including the ability to decode the genotype and construct the described machine to facilitate self-reproduction. This paper presents an exploratory model which implements the von Neumann architecture for selfreproduction within the pre-existing evolutionary platform of Tierra. Initially, the memory image of the automaton's genotype and phenotype are physically identical, and each symbol in memory may be interpreted as either passive numerical data (g-symbol), or a functional instruction (p-symbol), depending on how the symbol is interpreted. If redundancy is introduced to a mutable genotype-phenotype mapping, the mapping system becomes non-invertible, rendering it impossible to compute an automaton's exact genotypic memory image by analysis of the phenotype alone. However, this noninvertible mapping may allow for a more robust genotype, increasing its robustness to fatal mutations and therefore increasing its ability to preserve its phenotypic form under perturbations.