intros a; case a; simpl in |- *.
unfold red in |- *; unfold nf in |- *; simpl in |- *; auto.
intros x c aP aQ H';
case
(Reducef A A0 A1 eqA plusA invA minusA multA divA cs eqA_dec n ltM ltM_dec
os aP (exist (fun a => canonical A0 eqA ltM a) x c));
simpl in |- *; auto.
intros x0; case x0; simpl in |- *; auto.
intros x1 c0 H'0 H'1.
apply rstar_rtopO; auto.
apply reduceplus_trans with (Q := aQ) (1 := cs) (y := x1); auto.
inversion H'0; auto.
apply inP_reduceplus with (Q := aP); auto.
intros a0 H'3.
apply Incl_inp_inPolySet with (P := aP); auto.
apply
reduceplus_mults_inv with (1 := cs) (a := unit (mks A A0 eqA n ltM x1 c0));
auto.
apply unit_nZ; auto.
apply unit_T1; auto.
inversion H'1; inversion H; auto.
Qed.

Theorem red_zerop :
forall (a : poly A0 eqA ltM) (P : list (poly A0 eqA ltM)),
red (nf a P) P -> zerop (nf a P).