Hi. We have just finished a painful three day track-down for a mysterious access violation/crash/undefined behavior bug and the cause has been tracked down to some graph library edge descriptors getting invalidated in a case that is completely undocumented (that in turn causing memory trashing and all the lovely things that follow...) When you have an adjacency_list graph with its EdgeList (not OutEdgeList) parameter set to vecS, then any add_edge() operation may invalidate all existing edge descriptors. This is not documented anywhere - not under the add_edge() operation and not under the 'Iterator and Descriptor Stability/Invalidation' section in adjacency_list.html which in fact explicitly states that add_edge() operation does not invalidate edge descriptors. Please, please, please document this whole EdgeList concept and how it interacts with the rest of the graph library. Also, this behavior is not consistent with add_vertex() which does not invalidate any existing vertex descriptors. Edge descriptors seem to contain a pointer directly into their graph's edge storage, and that causes them to be invalidated whenever that storage gets reallocated. Any reason why they should not be holding an index to that storage in case EdgeList=vecS similar to how vertex descriptors identify their vertex? That way this whole problem with add_edge() invalidating all existing edge descriptors would be avoided. Thanks in advance. Best regards, Jurko Gospodnetić