The graphviz_write function is inconsistent in how it writes vertices. When it write the vertex itself, it uses get(vertex_index, ...), but when it writes the edges, it just writes the vertex descriptor. When using adjacency_list< listS, listS, bidirectionalS,... >, this produces bad output (the edges list their endpoints by hexadecimal address values). Here's a patch: *** graphviz.hpp.orig 2004-05-07 12:00:21.000000000 -0700 --- graphviz.hpp 2004-05-07 11:34:11.000000000 -0700 *************** *** 266,272 **** } typename graph_traits<Graph>::edge_iterator ei, edge_end; for(tie(ei, edge_end) = edges(g); ei != edge_end; ++ei) { ! out << source(*ei, g) << Traits::delimiter() << target(*ei, g) << " "; epw(out, *ei); //print edge attributes out << ";" << std::endl; } --- 266,272 ---- } typename graph_traits<Graph>::edge_iterator ei, edge_end; for(tie(ei, edge_end) = edges(g); ei != edge_end; ++ei) { ! out << get(vertex_index, source(*ei, g)) << Traits::delimiter() << get(vertex_index, target(*ei, g)) << " "; epw(out, *ei); //print edge attributes out << ";" << std::endl; } -- ^.-.^ Mark Purtill <mpurtill@softwarerevolution.com> (425)284-2770 ((")) Software Revolution 11332 NE 122nd Way Kirkland WA 98034-6931