reserve U for Universe;
reserve x for Element of U;
reserve U1,U2 for Universe;

theorem Th79:
  comp Trivial-addLoopStr(x) is Element of U
  proof
    set Tx = Trivial-addLoopStr(x);
    {x} is Element of U;
    then reconsider y = the carrier of Tx as Element of U;
    [:y,y:] is Element of U;
    hence thesis by CLASSES4:13;
  end;
