Three metaheuristics for the construction of constant GC-content DNA codes

DNA codes are sets of words of fixed length n over the alphabet {A, C, G, T} which satisfy a number of combinatorial conditions. The combinatorial conditions considered are (i) minimum Hamming distance d, (ii) fixed GC-content and, in some cases (iii) minimum distance d between any codeword and the reverse Watson-Crick complement of any codeword. The problem is to find DNA codes with the maximum number of codewords. In this paper three different meta-heuristic approaches for the problem are discussed, and the outcome of an extensive experimental campaign, leading to many new best-known codes, is presented.