intros a b Q H'; elim H'; auto.
intros p q H'0 H'1 H'2 H'3.
apply reduceplus_cb with (a := p); auto.
Qed.

Theorem reduce_cb1 :
forall (a : poly A0 eqA ltM) (b : list (Term A n))
(Q : list (poly A0 eqA ltM)),
reduce A A0 A1 eqA invA minusA multA divA eqA_dec n ltM ltM_dec Q
(s2p A A0 eqA n ltM a) b -> CombLinear (a :: Q) b.