fact: Parameter symb_in_term_list_app : forall f l1 l2, symb_in_term_list f (l1 ++ l2) = orb (symb_in_term_list f l1) (symb_in_term_list f l2).
imports: Coq(Recdef List Arith Setoid) CoLoR(closure more_list list_permut list_set decidable_set)