Computing Maximum Flows in Undirected Planar Networks with Both Edge and Vertex Capacities

We study the maximum flow problem in an undirected planar network with both edge and vertex capacities (EVC-network). A previous study reduces the minimum cut problem in an undirected planar EVC-network to the minimum edge-cut problem in another planar network with edge capacity only (EC-network), thus the minimum-cut or the maximum flow value can be computed in O(nlogn) time. Based on this reduction, in this paper we devise an O(nlogn) time algorithm for computing the maximum flow in an undirected general planar EVC-network and an O(n) time algorithm for computing the maximum flow in an undirected (s,t)-planar EVC-network. As a result, the maximum flow problem in undirected planar EVC-networks is as easy as the problem in undirected planar EC-networks in terms of computational complexity