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 Th55:
  A+ c= A*
proof
  A |^.. 1 c= A* by Th9;
  hence thesis by Th50;
end;
