Hi all I have a problem with an graph which is undirected. I thought that this meant that an edge (u,v) was the same as an edge (v,u) however when I insert (u,v) into a map and later asks the map to find (v,u) then the map does not find it. s=edge(target(*oei,graph_),source(*oei,graph_),graph_).first; EMap.insert(EdgeElementPair(s,p)); Esp=NULL; s=edge(source(*oei,graph_),target(*oei,graph_),graph_).first; Esp = EMap[s]; how can this be???? My graph is: typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, VertexProperties, EdgeProperties, GraphProperties> Graph; Thanks Line