Improving migration by diversity

We present an improvement to distributed GAs based on migration of individuals between several concurrently evolving populations. The idea behind our improvement is to not only use the fitness of an individual as criterion for selecting the individuals that migrate, but also to consider the diversity of individuals versus the currently best individual. We experimentally show that a distributed GA using a weighted sum of fitness and a diversity measure for selecting migrating individuals finds the known optimal solutions to benchmark problems from literature (that offer a lot of local optima) on average substantially faster than the distributed GA using only fitness for selection. In addition, the run times of several runs of the distributed GA to the same problem instance vary much less with our improvement than in the base case, thus resulting in a more stable behavior of a distributed GA of this type.