Morning, all. When the attached source code is compiled as is, the program works as expected. If the first #if condition is set to 0, the program garbles some output before crashing. If second #if condition is then set to 1, the program outputs much less, but it still crashes. Without the undirectedS property tag, the program works as expected, regardless of the #if conditions. I'm using the MinGW compiler bundled with Dev-C++ 4.9.8.5 and linking to the Boost libraries downloaded from CVS as of today, 0830 EST. I don't use the adjacency_matrix class template except for testing, so this is no showstopper, but it does seem to put a crimp on genericity. Feedback appreciated! Cromwell Enage __________________________________ Do you Yahoo!? Yahoo! Finance: Get your refund fast by filing online. http://taxes.yahoo.com/filing.html