Hi, In Hill Climbing algorithm, before applying an operation "add_edge", "reverse_edge" or "remove_edge", I need to check whether the graph will be a Directed Acyclic Graph (DAG) or not. So there is recursive function but in some cases it goes in infinite loop and gives "stack overflow" error. //======= Function ======= bool myAlgo::remainsADAG(const Node_type& nodeInit, const Node_type& node, const Graph_type& graph) { graph_traits<Graph_type>::adjacency_iterator vi, vi_end; tie(vi, vi_end) = adjacent_vertices(node, graph); for (; vi != vi_end; ++vi) { if ((*vi == nodeInit) || (!remainsADAG(nodeInit, *vi, graph))) return false; } return true; } ============== e.g. for Graph 12->19->20->23 19->24->31->18>19 18->32 To test if there is a directed path between v12 and v32 it goes as: 12->19->20->23 24->31->18>19 *There is an infinite loop{18->19->20->23, 24->31->18}.* ================= Can some one help me or is there any other easy way to find a directed path between two nodes in boost graph? Thanks in advance. YASIN