unfold incl in |- *; simpl in |- *; auto.
intros a L1 L2 H' a0 H'0.
case (addEnd_cons A A0 eqA n ltM) with (1 := H'0); auto.
Qed.

(* Specifications: *)
Theorem genOCp_redln :
forall aL1 R : list (poly A0 eqA ltM),
incl aL1 R ->
forall a b : poly A0 eqA ltM,
In a aL1 -> In b aL1 -> redIn a b aL1 (genOCPf aL1) R.