
theorem
  for T being with_equivalence naturally_generated non empty TopRelStr,
      A being Subset of T holds
    card Kurat7Set A <= 3
  proof
    let T be with_equivalence naturally_generated non empty TopRelStr,
        A be Subset of T;
    Kurat7Set A = { A, Cl A, Int A } by Seven1;
    hence thesis by CARD_2:51;
  end;
