proposition: Theorem canonical_spminusf : forall (a b : Term A n) (nZb : ~ zeroP (A:=A) A0 eqA (n:=n) b) (p q : list (Term A n)), canonical A0 eqA ltM p -> canonical A0 eqA ltM q -> divP A A0 eqA multA divA n a b -> canonical A0 eqA ltM (spminusf a b nZb p q).
proof: Proof. Proof using plusA os cs. unfold spminusf in |- *. intros a b nZb p q H' H'0 H'1; apply canonical_minuspf with (1 := cs); auto. Qed.