reserve x, x1, x2, y, X, D for set,
  i, j, k, l, m, n, N for Nat,
  p, q for XFinSequence of NAT,
  q9 for XFinSequence,
  pd, qd for XFinSequence of D;

theorem Th24:
  card Domin_0(n,0) = 1
proof
  Domin_0(n,0)={n-->0} by Th23;
  hence thesis by CARD_1:30;
end;
