Selection by Parts: ‘Selection in Two Episodes’ in Evolutionary Algorithms

Natural selection is the central concept of Darwinian evolution and hence selection is central for evolutionary computation. Naive models of evolution define natural selection as a process which brings in differential reproductive capabilities in organisms of a population, and hence, evolutionary algorithms implement selection by differential reproduction: the fittest members of the population are reproduced preferentially at the expense of the less fit members of the population. Formal models in evolutionary biology often subdivide selection into components called ‘episodes of selection’ to capture the different complex mechanisms of nature by which Darwinian evolution can occur. In this paper we introduce the concept of ‘episodes of selection’ in evolutionary computation by means of “A Conceptual Evolutionary model”(ACE-model). This model captures selection in two episodes in two phases of evolutionary cycle. Here we give formal description of ACE-model, in which one can mechanize the two phases in different possible ways. To demonstrate the concept of episodes of selection we propose evolutionary algorithms based on ACE-model, by giving simple mechanisms for implementation of two phases. Finally we discuss the importance of introducing episodes of selection in evolutionary algorithms by simulations of proposed evolutionary algorithms for function optimization.