
theorem Th24:
  for I being non degenerated domRing-like commutative Ring for u,
  v being Element of Quot.I holds (quotmult(I)).(u,v)=(quotmult(I)).(v,u)
proof
  let I be non degenerated domRing-like commutative Ring;
  let u,v be Element of Quot.I;
  (quotmult(I)).(u,v) = qmult(u,v) by Def13
    .= qmult(v,u) by Th13
    .= (quotmult(I)).(v,u) by Def13;
  hence thesis;
end;
