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+) ^^ A
proof
  thus A ^^ (A+) = A ^^ (A |^.. 1) by Th50
    .= (A |^.. 1) ^^ A by Th23
    .= A+ ^^ A by Th50;
end;
