Definition Leibnitz_set (A : Type) : Setoid := Build_Setoid (eqT_equiv A).

(* Specifications: *)
Lemma Leibnitz_set_prop : forall (A : Type) (x y : Leibnitz_set A), Equal x y -> x = y.
Lemma Leibnitz_set_prop_rev : forall (A : Type) (x y : Leibnitz_set A), x = y -> Equal x y.