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...

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...

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...