Hello. I believe I found a bug in the remove_edge function, when the graph is directed and allows parallel edges. Sometimes an edge simply isn't removed. I think the problem is that remove_edge uses edge_range internally, but this function needs an ordered EdgeList (such as multisetS), and doesn't work properly when it's something like listS. The attached file shows the problem. It builds a simple graph with a loop, adds a parallel edge, and tries to remove it. The output of the program is: number of edges before removal: 5 number of edges after removal: 5 When EdgeList is changed from listS to multisetS, it works as it should: number of edges before removal: 5 number of edges after removal: 4 I'm using Boost 1.32.0, with GCC 3.4.3 on GNU/Linux. Thanks. -- Tiago de Paula Peixoto <tiago@forked.de>