intros p; elim p; simpl in |- *; auto.
intros q a b H'; elim H'; auto.
intros a l H' q a0 b H'0 H'1 H'2 H'3.
elim H'0; [ intros H'4; rewrite H'4; clear H'0 | intros H'4; clear H'0 ].
change
(In a0
(minuspf A A0 A1 eqA invA minusA multA eqA_dec n ltM ltM_dec
(pX a0 l) (pX b q))) in |- *.
rewrite <- minuspf_inv1_eq; simpl in |- *; auto.
case (ltT_dec A n ltM ltM_dec a b); intros test;
[ case test; clear test; intros test | idtac ].
absurd (ltT ltM b a0); auto.
apply ltT_not_ltT; auto.
generalize H'4 H'2; elim l; simpl in |- *; auto.
intros H'0; elim H'0; auto.
intros a1 l0 H'0 H'5; elim H'5;
[ intros H'6; rewrite <- H'6; clear H'5 | intros H'6; clear H'5 ];
auto.
intros H'5; apply (ltT_trans A n ltM os) with (y := a); auto.
apply (canonical_pX_order A A0 eqA) with (l := l0); auto.
intros H'5; apply H'0; auto.
change (canonical A0 eqA ltM (pX a l0)) in |- *.
apply canonical_skip_fst with (b := a1); auto.
change
(In a0
(minuspf A A0 A1 eqA invA minusA multA eqA_dec n ltM ltM_dec
(pX a l) (pX b q))) in |- *.
rewrite <- minuspf_inv1_eq; simpl in |- *; auto.
right; auto.
apply H'; auto.
apply canonical_imp_canonical with (a := a); auto.
absurd (ltT ltM b a0); auto.
apply ltT_not_ltT; auto.
apply eqT_compat_ltTr with (b := a); auto.
generalize H'4 H'2; elim l; simpl in |- *; auto.
intros H'0; elim H'0; auto.
intros a1 l0 H'0 H'5; elim H'5;
[ intros H'6; rewrite <- H'6; clear H'5 | intros H'6; clear H'5 ];
auto.
intros H'5; apply (canonical_pX_order A A0 eqA) with (l := l0); auto.
intros H'5; apply H'0; auto.
change (canonical A0 eqA ltM (pX a l0)) in |- *.
apply canonical_skip_fst with (b := a1); auto.
Qed.

Theorem minus_is_reduce :
forall (Q : list (poly A0 eqA ltM)) (a : Term A n)
(nZa : ~ zeroP (A:=A) A0 eqA (n:=n) a) (q : list (Term A n)),
inPolySet A A0 eqA n ltM (pX a q) Q ->
forall u : Term A n,
divP A A0 eqA multA divA n u a ->
forall p : list (Term A n),
canonical A0 eqA ltM p ->
In u p ->
reduce A A0 A1 eqA invA minusA multA divA eqA_dec n ltM ltM_dec Q p
(minuspf A A0 A1 eqA invA minusA multA eqA_dec n ltM ltM_dec p
(mults (A:=A) multA (n:=n)
(divTerm (A:=A) (A0:=A0) (eqA:=eqA) divA (n:=n) u (b:=a) nZa)
(pX a q))).