reserve
  x for object, X for set,
  i, n, m for Nat,
  r, s for Real,
  c, c1, c2, d for Complex,
  f, g for complex-valued Function,
  g1 for n-element complex-valued FinSequence,
  f1 for n-element real-valued FinSequence,
  T for non empty TopSpace,
  p for Element of TOP-REAL n;

theorem Th24:
  for X being complex-functions-membered set,
      f being complex-valued Function holds
  -f in X iff f in (-)X
  proof
    let X be complex-functions-membered set,
    f be complex-valued Function;
    --f = f & (-)(-)X = X;
    hence thesis by Def3;
  end;
