proposition: Corollary paco4_mult: forall r, paco4 gf (paco4 gf r) <4= paco4 gf r.
proof: Proof. intros; eapply paco4_mult_strong, paco4_mon; [apply PR|..]; intros; left; assumption. Qed.
imports: Program.Basics Paco(paconotation_internal paco_internal pacotac_internal)