intros L p q H; apply Cb_incl with (1 := cs) (P := p :: L); auto.
elim L; simpl in |- *; auto.
intros a l H0 a0 H1; elim H1; clear H1; intros H1; auto.
case H1; auto.
Qed.

Theorem Cb_trans_cons :
forall (L : list (poly A0 eqA ltM)) (p q : poly A0 eqA ltM),
Cb A A0 eqA plusA multA eqA_dec n ltM ltM_dec q (p :: L) ->
Cb A A0 eqA plusA multA eqA_dec n ltM ltM_dec p L ->
Cb A A0 eqA plusA multA eqA_dec n ltM ltM_dec q L.