intros a p q; case q; simpl in |- *; auto.
intros H' H'0; rewrite minuspf_pO_refl_eq; rewrite minuspf_pO_refl_eq; auto.
intros a0 l H' H'0.
change
(eqP A eqA n (pX a (minuspf p (pX a0 l))) (minuspf (pX a p) (pX a0 l)))
in |- *; apply minuspf_inv1; auto.
apply (canonical_pX_order A A0 eqA) with (l := l); auto.
Qed.

Theorem minuspf_pOmults_eq :
forall p : list (Term A n),
minuspf (pO A n) p =
mults (A:=A) multA (n:=n) (invTerm (A:=A) invA (n:=n) (T1 A1 n)) p.