I've hit the wall with the Graph library. I cannot seem to resolve the error shown below. This is probably my rather limited experience with complicated template parameters. What is the first thing to try with these sorts of errors? My graph classes do not define source and target, but rely on the template provided in the Graph library. I've tried adding them explicitly to the class without success. The 'target' template is defined as: template <typename G> typename filtered_graph_base<G>::vertex_descriptor target(typename filtered_graph_base<G>::edge_descriptor e, const filtered_graph_base<G>& g) { return target(e, g.m_g); } The ambiguous call to 'target' occurs here: template struct edge_predecessor_recorder : public base_visitor > { typedef Tag event_filter; edge_predecessor_recorder(PredEdgeMap pa) : m_predecessor(pa) { } template void operator()(Edge e, const Graph& g) { put(m_predecessor, target(e, g), e); } PredEdgeMap m_predecessor; }; Notice that the 'target' template takes one parameter ('G') and the 'operator()' template takes two parameters ('Edge' and 'Graph'). Notice also below the occurrence of both 'G' and 'Graph' in the 'candidates are' section. Might this be fixed as: template <class Graph> void operator()(typename Graph::edge_descriptor e, const Graph& g) { put(m_predecessor, target(e, g), e); } ??? THK /usr/include/boost/graph/edmunds_karp_max_flow.hpp:232: instantiated from 'typename boost::detail::edge_capacity_value::type boost::edmunds_karp_max_flow(Graph&, typename boost::graph_traits<G>::vertex_descriptor, typename boost::graph_traits<G>::vertex_descriptor, const boost::bgl_named_params&) [with Graph = FlowCapacitySQLDiGraph, P = edge_index_property_map, T = boost::edge_residual_capacity_t, R = boost::no_property]' postgraph.cpp:1092: instantiated from here /usr/include/boost/graph/visitors.hpp:176: error: call of overloaded 'target(FlowCapacitySQLDiGraph::edge_descriptor&, const boost::filtered_graph >, boost::keep_all>&)' is ambiguous /usr/include/boost/graph/filtered_graph.hpp:322: note: candidates are: typename boost::filtered_graph_base<G>::vertex_descriptor boost::target(typename boost::filtered_graph_base<G>::edge_descriptor, const boost::filtered_graph_base<Graph>&) [with G = FlowCapacitySQLDiGraph] /usr/include/boost/graph/graph_traits.hpp:154: note: T std::target(std::pair<_ForwardIterator, _ForwardIterator>, const G&) [with T = unsigned int, G = boost::filtered_graph >, boost::keep_all>] make: *** [postgraph.o] Error 1 -- Timothy H. Keitt http://www.keittlab.org/