Hi, here is a minimal version. The code compiles however in the graph_properties struct i would like to define a traits graph type as it is possible for vertex_descriptors. // begin code #include <iostream> #include <map> #include <boost/graph/adjacency_list.hpp> typedef boost::adjacency_list_traits<boost::listS, boost::vecS, boost::bidirectionalS> link_adjacency_list_traits; struct vertex_properties { std::map <int, link_adjacency_list_traits::edge_descriptor > used_colors; // this one works fine, i can use a traits::edge_descriptor }; struct graph_properties { int delta; // link_adjacency_list_traits::??? g; // i need a 'traits_graph', too // link_graph g; is not possible because its definition needs // the definition of graph_properties // how to declare it? // but out_degree (u, g) does not need to know any properties }; struct edge_properties { int color; }; typedef boost::adjacency_list < boost::listS, boost::listS, boost::bidirectionalS, vertex_properties, edge_properties, graph_properties> link_graph; int main () { link_graph g; } // end code best regards christoph