namespace boost {
  namespace algorithm {
    template<typename ForwardIterator1, typename ForwardIterator2> 
      bool is_permutation(ForwardIterator1, ForwardIterator1, 
                          ForwardIterator2, ForwardIterator2);
    template<typename ForwardIterator1, typename ForwardIterator2, 
             typename BinaryPredicate> 
      bool is_permutation(ForwardIterator1, ForwardIterator1, 
                          ForwardIterator2, ForwardIterator2, 
                          BinaryPredicate);
  }
}