proposition: Lemma iter_invariant : forall (n:nat) (A:Type) (f:A -> A) (Inv:A -> Prop), (forall x:A, Inv x -> Inv (f x)) -> forall x:A, Inv x -> Inv (iter n f x).
proof: Proof. intros; apply iter_ind; trivial. Qed.
imports: NAxioms NProperties OrdersFacts DecidableClass