Hi, when testing boost graph 1.46 isomorphism on two graphs of size 11869 on x86_64-suse-linux, g++ 4.6.2, compiled at various levels of optimization, I consistently get the following error. (on very small graphs, everything seems to work) Could this be due to a problem of recursion/stack size due to the size of the graph? Up to what size of graph is the isomorphism program sure to work? Thanks, Chris Program received signal SIGSEGV, Segmentation fault. 0x00000000004099a6 in boost::iterator_core_access::equal >, boost::no_property>*, std::vector >, boost::no_property>, std::allocator >, boost::no_property> > > >, unsigned long, boost::detail::edge_desc_impl, long>, boost::detail::out_edge_iter<__gnu_cxx::__normal_iterator >, boost::no_property>*, std::vector >, boost::no_property>, std::allocator >, boost::no_property> > > >, unsigned long, boost::detail::edge_desc_impl, long> > (f1=..., f2=...) at /usr/include/boost/iterator/iterator_facade.hpp:535 535 return f1.equal(f2);