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

theorem
  (A*)? = A* & (A?)* = A*
proof
  thus (A*)? = {<%>E} \/ (A*) by Th76
    .= A* by FLANG_1:48,ZFMISC_1:40;
  thus (A?)* = ({<%>E} \/ A)* by Th76
    .= A* by FLANG_1:48,68;
end;
