intros a b Q H'.
apply Cb_incl with (P := Q); simpl in |- *; auto.
intros a0 H'0; apply addEnd_id2; auto.
Qed.

Theorem Cb_sp :
forall (a b : poly A0 eqA ltM) (Q : list (poly A0 eqA ltM)),
Cb a Q -> Cb b Q -> Cb (spolyp a b) Q.