(** Induction on the right transitive step *)

(* Specifications: *)
Lemma rt1n_ind_right : forall (P : A -> Prop) (z:A),
P z ->
(forall x y, R x y -> clos_refl_trans_1n R y z -> P y -> P x) ->
forall x, clos_refl_trans_1n R x z -> P x.