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...

The inverse p-median problem with variable edge lengths on graphs is to modify the edge lengths at minimum total cost with respect to given modification bounds such that a prespecified set of p vertices becomes a p-median with respect to the new edge lengths. The problem is shown to be strongly...

This paper deals with transportation problems whose demand vectors can be permuted. This additional freedom makes these problems ??-hard, even in the case that the cost matrix fulfills a Monge property. We outline some solution procedures based on good lower and upper bounds. Copyright...