The Use of Collective Memory in Genetic Programming

Summary

Memory plays an important part in the development of the collective and individual fitness of a biological species. Knowledge acquired by teaching and experience is stored in memory and retrieved when an individual is required to perform a task or solve a problem. In this article we discuss the concept of memory in a genetic programming (GP) system. The memory operator we introduce is used in conjunction with, and in support of, the traditional selection, crossover, and mutation operators. We implement a form of memory by preserving the component parts of good designs from previous generations. The memory is used as a pool of genetic material which is introduced into later generations by a form of mutation. It thus acts as a ’tribal folklore’ or cultural memory for the system. Using the memory operator, significant improvements in performance can be achieved on some problems. We believe that these improvements may be achievable in most areas in which Genetic Programming is applied, given suitable encodings, fitness measures and parameter tuning.