Local search with perturbations for the prize-collecting Steiner tree problem in graphs

Given an undirected graph with prizes associated with its nodes and weights associated with its edges, the prize-collecting Steiner tree problem consi sts of finding a subtree of this graph which minimizes the sum of the weigh ts of its edges plus the prizes of the nodes not spanned. In this paper, we describe a multistart local search algorithm for the prize-collecting Stei ner tree problem, based on the generation of initial solutions by a primal- dual algorithm using perturbed node prizes, Path-relinking is used to impro ve the solutions found by local search and variable neighborhood search is used as a post-optimization procedure. Computational experiments involving different algorithm variants are reported. Our results show that the local search with perturbations approach found optimal solutions on nearly all of the instances tested. (C) 2001 John Wiley & Sons, Inc.