virtual ex series(const relational & r, int order) const;
virtual ex subs(const lst & ls, const lst & lr) const;
virtual ex normal(lst &sym_lst, lst &repl_lst, int level=0) const;
+ virtual ex to_rational(lst &repl_lst) const;
virtual numeric integer_content(void) const;
virtual ex smod(const numeric &xi) const;
virtual numeric max_coefficient(void) const;