proposition: Lemma Fix_Proper_hetero {a a'} (Ha : RA a a') : @RP a a' Ha (Fix Rwf P F a) (Fix Rwf' P' F' a').
proof: Proof. revert a' Ha. induction (Rwf a) as [a Hlt IHwf]. intros a' Ha. rewrite (Fix_eq Rwf), (Fix_eq Rwf') by assumption. apply HF; intros. apply IHwf; assumption. Qed.
imports: Coq.Setoids.Setoid Coq.Program.Program Coq.Program.Wf Coq.Arith.Wf_nat Coq.Classes.Morphisms Coq.Init.Wf Coq.Lists.SetoidList Coq.Arith.PeanoNat Fiat.Common.Coq__8_4__8_5__Compat