proposition: Lemma FixWf_unfold_ext_step : forall (A : Type) (R : relation A) (WF : WellFounded R) (P : A -> Type) (step : forall x : A, (forall y : A, R y x -> P y) -> P x) (x : A) (step' : forall y : A, R y x -> P y), step' = (fun (y : A) (_ : R y x) => FixWf P step y) -> FixWf P step x = step x step'.
proof: Proof. intros. rewrite FixWf_unfold_ext, H. reflexivity. Qed.
imports: Coq(Wf_nat Relations) Coq(Wellfounded Relation_Definitions) Coq(Relation_Operators Lexicographic_Product Wf_nat) Equations(Init Signature) Equations.CoreTactics Equations.Prop.Classes Equations.Prop.EqDec Equations.Prop.DepElim Equations.Prop.Constants