unfold pO in |- *; intros p a H'; inversion H'; auto.
Qed.

Theorem eqp_invT1_pO_is_pO :
forall p : list (Term A n),
eqP A eqA n (mults (invTerm (A:=A) invA (n:=n) (T1 A1 n)) p) (pO A n) ->
eqP A eqA n p (pO A n).