In file http://boost.org/libs/iterator/doc/iterator_facade.html operator < (iterator_facade<...> const& lhs, iterator_facade<...> const& rhs); Returns: if is_convertible<Dr2,Dr1>::value then ((Dr1 const&)lhs).distance_to((Dr2 const&)rhs) < 0. Should By ((Dr1 const&)lhs).distance_to((Dr2 const&)rhs) > 0. Same with other operators.