Evolutionary Algorithms for Optimal Error-Correcting Codes

The maximum possible number of codewords in a q-ary code of length n and minimum distance d is denoted Aq(n,d). It is a fundamental problem in coding theory to determine this value for given parameters q, n and d. Codes that attain the maximum are said to be optimal. Unfortunately, for many different values of these parameters, the maximum number of codewords is currently unknown: instead we have a known upper bound and a known lower bound for this value. In this paper, we investigate the use of different evolutionary algorithms for improving lower bounds for given parameters. We relate this problem to the well-known Maximum Clique Problem. We compare the performance of the evolutionary algorithms to Hill Climbing, Beam Search, Simulated Annealing, and greedy methods. We found that the GAs outperformed all other algorithms in general; furthermore, the difference in performance became more significant when considering harder test cases.