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