proposition: Lemma irreducible_inv_px_l : forall (Q : list (poly A0 eqA ltM)) (a : Term A n) (p : list (Term A n)), canonical A0 eqA ltM (pX a p) -> irreducible Q (pX a p) -> irreducible Q (pX a (pO A n)).
proof: Proof. Proof using plusA cs. unfold irreducible in |- *. intros Q a p H' H'0 q; red in |- *; intros H'1. inversion_clear H'1. apply H'0 with (q := spminusf A A0 A1 eqA invA minusA multA divA eqA_dec n ltM ltM_dec a b nZb p q0); auto. inversion_clear H; auto. Qed.