Theorem zerop_elim_Cb : forall (L : list (poly A0 eqA ltM)) (p q : poly A0 eqA ltM), zerop A A0 eqA n ltM p -> 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 q L.