Hello, I build a visitor for an undirected graph which finds the cut-vertices of a given undireted graph or subgraph. I haven't found an implementation of the algorithm in the bgl. Maybe it would have been possible to use the predecessor_recorder for that. But then all the information which can be found directly while doing the df-search we have to find after having performed that search first. The interface of the undirected_dfs function doesn't take visitors via reference, so it wasn't possible to use that function. I had to call the detail::undir_dfv_impl function instead because that function takes a visitor reference and I had to recreate a function with the behaviour of the undirected_dfs. What reasons lead to the decision to disable passing a visitor by reference directly to undirected_dfs? What reasons lead to the decision to pass a const graph to a visitor function? Some useful things are disabled by that (but maybe also some bad things). Cheers, Stephan