intros a b Q H'.
apply reduceplus_cb2_lem with (b := s2p A A0 eqA n ltM b); auto.
case a; auto.
Qed.

(* Specifications: *)
Theorem reducestar_cb2 :
forall (a b : poly A0 eqA ltM) (Q : list (poly A0 eqA ltM)),
reducestar A A0 A1 eqA invA minusA multA divA eqA_dec n ltM ltM_dec Q
(s2p A A0 eqA n ltM a) (s2p A A0 eqA n ltM b) ->
CombLinear (b :: Q) (s2p A A0 eqA n ltM a).