reserve E, x, y, X for set;
reserve A, B, C for Subset of E^omega;
reserve a, a1, a2, b for Element of E^omega;
reserve i, k, l, m, n for Nat;

theorem
  A+ ^^ A = A |^.. 2
proof
  A+ ^^ A = A+ ^^ (A |^ 1) by FLANG_1:25
    .= A |^.. (1 + 1) by Th75;
  hence thesis;
end;
