A genetic algorithm for the p-median problem with pos/neg weights

Let a connected undirected graph G = (V, E) be given. In the classical p-median problem we want to find a set X containing p points in G such that the sum of weighted distances from X to all vertices in V is minimized. We consider the semi-obnoxious case where every vertex has either a positive or negative weight. In this case we have two different objective functions: the sum of the minimum weighted distances from X to all vertices and the sum of the weighted minimum distances. In this paper we propose a genetic algorithm for both problems. Computational results are compared with a previously investigated variable neighborhood search algorithm.