theorem
  for d,d9 being UnOp of product a st
  for f being Element of product a, i being Element of dom a holds
    (d.f).i = (d9.f).i holds d = d9
proof
  let d,d9 be UnOp of product a such that
A1: for f being Element of product a, i being Element of dom a holds
  (d.f).i = (d9.f).i;
  now
    let f be Element of product a;
    dom (d.f) = dom a & dom (d9.f) = dom a by CARD_3:9;
    hence d.f = d9.f by A1;
  end;
  hence thesis by FUNCT_2:63;
end;
