
theorem
  for I being non degenerated domRing-like commutative Ring for u being
  Element of the_Field_of_Quotients(I) holds (quotmultinv(I)).(u) is Element of
  the_Field_of_Quotients(I)
proof
  let I be non degenerated domRing-like commutative Ring;
  let u be Element of the_Field_of_Quotients(I);
  reconsider s = u as Element of Quot.I;
  (quotmultinv(I)).(u) = qmultinv(s) by Def15;
  hence thesis;
end;
