Spider network search strategy for p-location problems

This paper deals with the strategic level of emergency health care management. Its main research topic consists in searching suitable deployment of service centers, from which the ambulance vehicles are sent to the demand points in case of emergency. Such problem can be solved by finding the optimal or at least a good enough solution of the weighted p-median problem. Due to growing number of applications of the location problems, several exact and heuristic methods have been recently developed. In this paper, we introduce a new strategy of heuristic solving method for the generalized min-sum p-location problem using a uniformly deployed set of p-median problem solutions. The set of solutions represents fixed points of a spider's network. The center of the network is determined by subsequent inspection of the shortest path connecting the current best-found solution and one of the fixed points. The inner nodes of the spider's network are obtained by inspections of paths, which connect neighboring fixed points. When series of the inner network nodes is finished, the connections of the general best-found solution and the inner nodes are inspected to improve the general best-found solution. Then a new series of inner nodes is created by inspecting the links between the neighboring current inner nodes. The process continues until some termination rule is met. The theoretical explanation is here accompanied by a brief computational study, the aim of which is to study its efficiency measured by computational time and the resulting solution accuracy.