proposition: Lemma mem_concat_1: forall a ls lc, mem equiv a ls -> mem equiv a (ls ++ lc).
proof: Proof. induction ls. intros. simpl in H. contradiction. intros. simpl. simpl in H. destruct H. left; trivial. assert (H0:= IHls lc). right. apply H0; trivial. Qed.
imports: Coq(Bool Peano List PeanoNat) CoLoR(closure more_list equiv_list list_permut dickson) Coq(Relations Wellfounded Arith Wf_nat Recdef Program Morphisms Lia) CoLoR(term_spec term decidable_set ordered_set NatCompat)