Force-Based Cooperative Search Directions in Evolutionary Multi-objective Optimization

In order to approximate the set of Pareto optimal solutions, several evolutionary multi-objective optimization (EMO) algorithms transfer the multiobjective problem into several independent single-objective ones by means of scalarizing functions. The choice of the scalarizing functions’ underlying search directions, however, is typically problem-dependent and therefore difficult if no information about the problem characteristics are known before the search process. The goal of this paper is to present new ideas of how these search directions can be computed adaptively during the search process in a cooperative manner. Based on the idea of Newton’s law of universal gravitation, solutions attract and repel each other in the objective space. Several force-based EMO algorithms are proposed and compared experimentally on general bi-objective ρMNK landscapes with different objective correlations. It turns out that the new approach is easy to implement, fast, and competitive with respect to a (μ+ λ)-SMS-EMOA variant, in particular if the objectives show strong positive or negative correlations.