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 |^ (0, n) \/ A |^.. (n + 1)
proof
  thus A* = A |^.. 0 by Th11
    .= A |^ (0, n) \/ A |^.. (n + 1) by Th7;
end;
