In trying to compile and run the Kevin Bacon example for graph in the 1.30.2 distribution of Boost, I was able to compile, but when I ran the executable, I got: kevin-bacon: /usr/local/boost-1.30.2/boost/token_iterator.hpp:75: void boost::detail::tokenizer_policy<Type, TokenizerFunc>::increment(Iterator&) [with Iterator = boost::iterator_adaptor<boost::detail::token_iterator_base<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >, boost::detail::tokenizer_policy<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::char_delimiters_separator<char, std::char_traits<char> > >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, const std::basic_string<char, std::char_traits<char>, std::allocator<char> >*, std::forward_iterator_tag, ptrdiff_t>, Type = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, TokenizerFunc = boost::char_delimiters_separator<char, std::char_traits<char> >]: Assertion `b.base().valid_' failed. Aborted Investigating led me to comment out the asserts on lines 69 and 75 of boost/token_iterator.hpp just to test. When I rebuilt without the asserts, I was able to run my executable with no problem with seemingly correct output. What purpose do the asserts serve, and why would they be failing? -tfo