reserve x, y for set;
reserve D for non empty set;
reserve UN for Universe;
reserve C for Category;
reserve O for non empty Subset of the carrier of C;
reserve G,H for AddGroup;
reserve V for Group_DOMAIN;

theorem Th29:
  Trivial-addLoopStr in GroupObjects(UN)
proof
  ex x st x in UN & GO x,Trivial-addLoopStr by Th28;
  hence thesis by Def22;
end;
