(* This file is copied from RamifyCoq project. *)
Require Coq.Setoids.Setoid.
Require Export Coq.Classes.Equivalence.
Require Export Coq.Sets.Ensembles.
intros.
split; intros [].
Qed.
Arguments Included {U} B C.
Arguments Same_set {U} B C.
Instance Included_proper (V: Type): Proper (Same_set ==> Same_set ==> iff) (@Included V).

Lemma left_Included_Union {A: Type}: forall P Q, Included P (Union A P Q).