Hi, I noticed that with boost 1.32 under gcc 3.4.3 there are cases when remove_edge fails to remove the edge in question. I put this with all kinds of details on bugtracker under http://sourceforge.net/tracker/index.php?func=detail&aid=1166401&group_id=7586&atid=107586 In short the problem appears to be the use of std::equal_range in the code for remove_edge. With a certain order of the vertex and edge creation it happens that equal_range returns an (end_of_list,end_of_list) pair instead of the range that includes the edge in question. I believe this is due to the list not being ordered according to the same "<" operator that std::equal_range invokes. So equal_ranges logic doesn't find the proper range, and remove_edge simply returns without warning and without removing the edge in question. There is more detail in the bug report mentioned above. I am just wondering about a good workaround. Currently I am considering to replace the equal_range call in my copy of the source but there may be a better way. ? Jean -- Jean Utke Argonne National Lab./MCS utke@mcs.anl.gov phone: 630 252 4552 cell: 630 363 5753