intros L p q H H0.
apply Cb_trans with (1 := cs) (b := p); auto.
apply Cb_cons_addEnd; auto.
Qed.

Theorem Cb_cons :
forall (p : poly A0 eqA ltM) (L : list (poly A0 eqA ltM)),
Cb A A0 eqA plusA multA eqA_dec n ltM ltM_dec
(nf A A0 A1 eqA plusA invA minusA multA divA cs eqA_dec n ltM ltM_dec os p
L) (p :: L).