proposition: Theorem canonical_spminusf_full : 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 (pX a p) -> canonical A0 eqA ltM (pX b 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. intros a b nZb p q H' H'0 H'1; apply canonical_spminusf; auto. apply canonical_imp_canonical with (a := a); auto. apply canonical_imp_canonical with (a := b); auto. Qed.