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 Dmult_is_mulpf : forall (a : Term A n) (nZa : ~ zeroP (A:=A) A0 eqA (n:=n) a) (p q : list (Term A n)), canonical A0 eqA ltM p -> canonical A0 eqA ltM q -> eqP A eqA n (Dmult a nZa (mults (A:=A) multA (n:=n) a p) q) (multpf A A0 eqA plusA multA eqA_dec n ltM ltM_dec p q).