Inductive Tlist : Type :=
  | Empty : Tlist
  | Concat1 : A -> Tlist -> Tlist.Inductive Tlist : Type :=
  | Empty : Tlist
  | Concat1 : A -> Tlist -> Tlist.Inductive Tlist : Type :=
  | Empty : Tlist
  | Concat1 : A -> Tlist -> Tlist.Fixpoint Equal_Tlist (l : Tlist) : Tlist -> Prop :=
  fun m : Tlist =>
  match l, m with
  | Empty, Empty => True
  | Empty, _ => False
  | Concat1 a l1, Concat1 b m1 => a =_S b /\ Equal_Tlist l1 m1
  | _, _ => False
  end.

(* Specifications: *)
Lemma Equal_Tlist_equiv : Equivalence Equal_Tlist.