Hi to all, if we want to find the shortest distance between *every* pair of vertices in a graph, we can use the Jonson's or Floyd-Warshall's algorithm, obtaining a NxN matrix of distances, where N is the total number of the graph's vertices. The problem is: how can I do if I don't need the distance of *every* pair of graph's vertices, but I'm interested in only a subset of vertices? In other words, I would to obtain a MxM matrix, where M<N. In every case, I'm not interested in path from the pairs, but only in the distance. My solution is to execute M times the Dijkstra algorithm from every vertex of the subset, and to abort every exploration when I've founded the Mth vertex of the subset. Are there something of more efficent? My graphs contain approximately 12 millions of vertices, but I'm interested in a subset of 10.000 vertices. Thanks in advance, Cosimo Calabrese.