Hello, Warning ahead - this is a newbie question. I need to find weak and strong components of a graph. So far, my code is as simple as it could be (edges being a std::vector of std::pair<unsigned,unsigned>): typedef adjacency_list <vecS, vecS, undirectedS> Graph; Graph G; for (Edges::const_iterator ei = edges.begin(); ei != edges.end();++ei) add_edge((*ei).first, (*ei).second, G); std::vector<int> component(num_vertices(G)); int num = connected_components(G, &component[0]); However, my vertices are not contiguously numbered. Hence, the following edges (8, 9) (9, 10) (12, 13) result in these connected components: 0: 0 1: 1 2: 2 3: 3 4: 4 5: 5 6: 6 7: 7 8: 8, 9, 10 9: 11 10: 12, 13 which is not what I want (just two wcc: 8, 9, 10 and 12, 13). I was reading into the property_map stuff, but as far as i understand, that would not help here. Do I have to remap the indices beforehand or is there a way to convince Boost that there are no other nodes than those in the edges? Best regards, Roman