proposition: Lemma gpaco4_dist_reverse clo r rg: (paco4 gf (rclo4 clo (rg \4/ r)) \4/ rclo4 clo r) <4= gpaco4 gf clo r rg.
proof: Proof. intros. destruct PR; cycle 1. - eapply gpaco4_rclo. apply H. - econstructor. apply rclo4_base. left. revert x0 x1 x2 x3 H. pcofix CIH; intros. _punfold H0; [|apply gf_mon]. pstep. eapply gf_mon. apply H0. intros. destruct PR. + apply rclo4_base. right. apply CIH, H. + eapply rclo4_mon. apply H. intros. right. apply CIH0. apply PR. Qed.
imports: Program.Basics Paco(paco4 pacotac)