intros aP H' Q a b H'0 H'1 H'2.
unfold genPcPf in |- *.
case (genPcPf0 a aP Q).
intros x H'3.
apply spolyp_cons_genPcP with (R := Q); auto.
Qed.
(* Now we can define the optimized version of Buchberger *)
Definition genOCPf : list (poly A0 eqA ltM) -> list (poly A0 eqA ltM).
intros H'; elim H'.
exact (nil (A:=poly A0 eqA ltM)).
intros a l rec; exact (genPcPf a l rec).
Defined.
(* Now we can define the optimized version of Buchberger *)

Theorem genOCPf_stable :
forall (a : poly A0 eqA ltM) (P : list (poly A0 eqA ltM)),
In a (genOCPf P) -> Cb A A0 eqA plusA multA eqA_dec n ltM ltM_dec a P.