proposition: Lemma well_formed_cf_alien : forall f l, arity f = AC -> well_formed_cf (Term f l) -> (forall t, In t l -> match t with | Var _ => True | Term g _ => f <> g end).
proof: Proof. intros f l Af [_ Ll]; rewrite Af in Ll; intuition. Qed.
imports: Coq(Relations List Arith Morphisms) CoLoR(more_list list_permut list_sort term_spec term_o equational_theory_spec equational_theory)