Hi, I have the following concept: template < class GRAPH, class EDGE_PREDICATE, class VERTEX_PREDICATE > class FilteredGraph { public: /// Defines an alias type to represent the filtered_graph typedef filtered_graph< GRAPH, EDGE_PREDICATE, VERTEX_PREDICATE > FilteredGraphContainer; // // some c'tors, member functions etc. // template< class VERTEXPROPERTIES > VERTEXPROPERTIES& properties(const Vertex& v) const { typename property_map<FilteredGraphContainer, vertex_properties_t>::const_type param = get(vertex_properties, graph_); return (param[v]); } // // some more stuff // }; When I want to use this code to access the properties of a vertex of the FilteredGraph, the compiler says that it can't find this function. I searched around and found some notes about returning a template. The most prevalent is that the compiler simply does not know which type the function should return and thus can't find a valid signature and complains. Is there a way to let it find the type via the property_map? Or some other ideas how to solve this issue? I experimented with: template< class VERTEXPROPERTIES > VERTEXPROPERTIES& properties(const Vertex& v) const { typename property_map<FilteredGraphContainer, vertex_properties_t>::const_type param = get(vertex_properties, graph_); property_traits< typename property_map<FilteredGraphContainer, vertex_properties_t>::const_type > prop_trait; return prop_trait.reference(param[v]); } but with no success. Except for this, I have no reason to include a template for VERTEXPROPERTIES generally to the class. So I would really like to keep that concept as it is. Thank you. Best, Cedric