hi list i am developping a scheduling algorithm usig boost graph library. I want to update the list of the ready tasks. for that , i develop a function template <class Vertex,class Graph> file://this tests if all parent of vertex v are scheduled // i.e v is a ready task bool isReady(const Vertex v,const Graph g){ typedef typename property_map<Graph, vertex_first_name_t>::const_type NamePA; NamePA name = get(vertex_first_name, g); typedef typename boost::property_traits<NamePA>::value_type NameType; // typename boost::property_map<Graph, vertex_index_t>::type id = get(vertex_index, g); NameType src_name; boost::graph_traits<Graph>::vertex_iterator vi; for (vi=in_edges(v,g).first; // XXXXXXXX vi!=in_edges(v,g); ++vi){ /// if (name[*vi]==false) return false; } return true; } and I call it from template <class Graph> void allocate1(Graph &g,vector<MACHINE> &m){ typedef typename property_map<Graph, vertex_first_name_t>::type NamePA; NamePA name = get(vertex_first_name, g); typedef typename boost::property_traits<NamePA>::value_type NameType; typename boost::property_map<Graph, vertex_index_t>::type id = get(vertex_index, g); typedef typename boost::graph_traits<Graph>::vertex_descriptor vertex; NameType src_name; boost::graph_traits<Graph>::vertex_iterator vi; typedef list<vertex> vlist; vlist readyTasks; cerr << "Machine number :" << m.size() << endl; ///////////// initialising the ready tasks list for (vi=vertices(g).first;vi!=vertices(g).second;++vi){ if (in_degree(*vi,g)==0) readyTasks.push_back(*vi); cerr << "pushing vertex "<<id[*vi]<<endl; } } /////////// for(vlist::iterator it=readyTasks.begin(); it!=readyTasks.end(); ++it){ name[*it].isScheduled(); file://the task has been scheduled for (vi=vertices(g).first;vi!=vertices(g).second;++vi){ vertex temp=*vi; if (isReady<vertex,Graph>(temp,g)==true) { readyTasks.push_back(*vi); cerr << "pushing vertex "<<id[*vi]<<endl; } } } } but the compiler (g++ 3.X on linux) returns me an error ( saying that it cannot find attribute .. and points me on line XXXXXXX) please, do you see any error in isReady() function. thanks adel