reserve E, x, y, X for set;
reserve A, B, C for Subset of E^omega;
reserve a, b for Element of E^omega;
reserve i, k, l, kl, m, n, mn for Nat;

theorem
  A |^ (1, 1) = A
proof
  thus A |^ (1, 1) = A |^ 1 by Th22
    .= A by FLANG_1:25;
end;
