Definition psi := phi.

(* Specifications: *)
Lemma psi_not_inj : forall a : U, In U H a -> ~ injective nat U (psi a).
Theorem remaining : forall a : U, In U H a -> exists r : nat, (exists m : nat, phi a r = phi a (S (S (r + m)))).
Theorem T_1_6_4 : Setsubgroup U H Gr.