Proof
fun (A : Ens) (P : Ens -> Prop) =>
REPLACEMENT_pr1 (Restriction P A) (Restriction_bounded P A).

(* Specifications: *)
Theorem Set_Of_pr2 :
forall (A : Ens) (P : Ens -> Prop) (X : Ens),
IN X (Set_Of A P) -> Restriction P A X.