Hi, On Fri, 1 Nov 2002, kweeheong wrote: tan.k.> After doing some more work, I believe the following information tan.k.> can be added. tan.k.> tan.k.> If DFS/BFS is invoked without a color map, an internal one is tan.k.> created. This can be seen in the code tan.k.> dfs_dispatch<detail::error_property_not_found>, for example. Yes. It also says this (rather tersely) in the documentation for BFS/DFS. UTIL/OUT: color_map(ColorMap color) ... Default: an iterator_property_map created from a std::vector of default_color_type of size num_vertices(g) and using the i_map for the index map. tan.k.> This means that DFS/BFS has access to a color map, whether tan.k.> user-provided or intenally-provided. tan.k.> tan.k.> However, the DFS/BFS visitor can only access a color map if passed tan.k.> from the user. It has no access to the internal color map. That is true. tan.k.> The same reasoning goes for the queue of vertices. tan.k.> tan.k.> tan.k.> Feedback and comments are welcome, esp if there is a different or tan.k.> better way. Here's how I would do it: 1. For pruning, use an external color map that gets passed to the visitor and the algorithm. 2. For early exit, throw an exception. Cheers, Jeremy ---------------------------------------------------------------------- Jeremy Siek http://php.indiana.edu/~jsiek/ Ph.D. Student, Indiana Univ. B'ton email: jsiek@osl.iu.edu C++ Booster (http://www.boost.org) office phone: (812) 855-3608 ----------------------------------------------------------------------