Performance guarantees of a greedy algorithm for minimizing a supermodular set function on comatroid

We consider the problem of minimizing a supermodular set function on comatroid whose special case is the well-known NP-hard minimization p-median problem. The main result of the paper is a tight bound on the performance guarantee of a greedy heuristic for this problem. As a corollary an analog of the Rado-Edmonds theorem for comatroids is obtained. (c) 2004 Published by Elsevier B.V.