Dear boost-users: I just start learning boost graph library and have a basic problem on using the remove_edge function in boost graph library. I would like to remove an edge in a multigraph. For a graph with two edges connect vertice 0 and 1, I would like to remove one of them, but kept the other. According to the user guide, remove_edge(u ,v , g) removes all occurrences of (u ,v). So I should use remove_edge(e ,g) instead. Here, e is a valid edge descriptor. For a single graph, g, I am able to perform both remove_edge(u ,v , g) and remove_edge(e ,g) operation. However, when I want to generalize the implementation to fit my need by putting graphs in a vector container, I got segmentation fault for remove_edge(e ,graph_list[0]). I really want to make remove_edge(e,g) and vector container work at the same time. So any suggestion that can help my bypass this difficulty is appreciated. Thanks a lot!! Yi-Ping *************************Here is the complete code************************* #include <iostream> #include <utility> #include <algorithm> #include <vector> #include "boost/graph/graph_traits.hpp" #include "boost/graph/adjacency_list.hpp" using namespace boost; typedef adjacency_list<vecS, vecS, undirectedS> UndirectedGraph; typedef boost::graph_traits<UndirectedGraph>::edge_iterator edge_iterator; int graph_show(UndirectedGraph &g); int main(int argc, char *argv[]) { UndirectedGraph g; typedef boost::graph_traits<UndirectedGraph>::edge_descriptor edge_descriptor; edge_descriptor ed; std::vector<edge_descriptor> edge_list; std::vector<std::vector<edge_descriptor> > graph_edge_list; std::vector<UndirectedGraph> graph_list; int nb=0; int Nl=4; bool inserted; while(nb<Nl) { tie(ed,inserted)=add_edge(nb,nb+1,g); edge_list.push_back(ed); tie(ed,inserted)=add_edge(nb,nb+1,g); edge_list.push_back(ed); graph_edge_list.push_back(edge_list); nb=nb+1; graph_list.push_back(g); } std::cout<<"size of the graph vector is: "<<graph_list.size()<<std::endl; remove_edge(graph_edge_list[0][0],graph_list[0]);//This is where the problem shows. //I got Segmentation fault (core dumped) //remove_edge(0,1,graph_list[0]); /*Remove edges by assigning vertices works fine, but that is not what I need.*/ for (int ig = 0; ig < Nl; ++ig) { std::cout<<"graph#"<<ig<<std::endl; std::cout<<"Size of edge_list is: "<<graph_edge_list[ig].size()<<std::endl; graph_show(graph_list[ig]); } std::cout<<"Success"<<std::endl; return 0; } int graph_show(UndirectedGraph &g) { std::cout<<"Number of edges is : "<<boost::num_edges(g)<<std::endl; std::cout<<"Number of vertices is : "<<boost::num_vertices(g)<<std::endl; std::pair<edge_iterator,edge_iterator> ei=edges(g); for (edge_iterator edge_iter = ei.first; edge_iter!=ei.second; ++edge_iter) { std::cout<<"("<< boost::source(*edge_iter,g)<<","<<boost::target(*edge_iter,g)<<")"<<std::endl; } typedef boost::graph_traits<UndirectedGraph>::vertex_iterator iter_v; std::cout<<"vertices(g)={ "; for (std::pair<iter_v,iter_v> p = vertices(g); p.first != p.second; ++p.first) { std::cout<< *p.first; std::cout<<" "; } std::cout<<"}"<<std::endl; return 0; }