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
  <%>E in B implies A c= A ^^ (B+) & A c= (B+) ^^ A
proof
  assume <%>E in B;
  then B+ = B* by Th57;
  hence thesis by FLANG_2:18;
end;
