How to Do Recombination in Evolution Strategies: An Empirical Study

In Evolution Strategies (ES) mutation is often considered to be the main variation operator and there has been relatively few attention on the choice of recombination operators. This study seeks to compare advanced recombination operators for ES, including multi-parent weighted recombination. Both the canonical $(\mu{+\atop,} \lambda)-$ES with mutative self-adaptation and the CMA-ES are considered. The results achieved on scalable (non-)separable test problem indicate that the right choice of recombination has an considerable impact on the performance of the ES. Moreover, the study will provide empirical evidence that weighted multi-parent recombination is a favorable choice for both ES variants.