Definition Dmult :
  forall (a : Term A n) (nZa : ~ zeroP (A:=A) A0 eqA (n:=n) a),
  list (Term A n) -> list (Term A n) -> list (Term A n).

Theorem spoly_reduceplus_pO : forall (Q : list (poly A0 eqA ltM)) (p q : list (Term A n)), inPolySet A A0 eqA n ltM q Q -> canonical A0 eqA ltM p -> reduceplus A A0 A1 eqA invA minusA multA divA eqA_dec n ltM ltM_dec Q (multpf A A0 eqA plusA multA eqA_dec n ltM ltM_dec p q) (pO A n).