proposition: Lemma gpaco4_step clo r rg: gf (gpaco4 clo rg rg) <4= gpaco4 clo r rg.
proof: Proof. intros. apply gpaco4_step_gen. eapply gf_mon. apply PR. intros. eapply gpaco4_mon. apply PR0. left; apply PR1. left; apply PR1. Qed.
imports: Program.Basics Paco(paco4 pacotac)