Well Prims is not supposed to have problems with negative cycles. However Dijkstra does. I believe the problem lies in prim_minimum_spanning_tree use of Dijkstra. Thanks Line ________________________________________ Fra: me22.ca@gmail.com [me22.ca@gmail.com] På vegne af Scott McMurray [me22.ca+boost@gmail.com] Sendt: 4. august 2009 18:14 Til: Line Blander Reinhardt Emne: Re: [Boost-users] prim_minimum_spanning_tree 2009/8/4 Line Blander Reinhardt :

Have done thanks. Was just wondering if it had been fixed in newer versions.

I think it fundamentally cannot be fixed, as the algorithm doesn't provide a way to detect the problematic conditions. ~ Scott