
theorem Th8:
  for L being upper-bounded antisymmetric non empty RelStr for X
  being non empty upper Subset of L holds Top L in X
proof
  let L be upper-bounded antisymmetric non empty RelStr, X be non empty upper
  Subset of L;
  consider y being object such that
A1: y in X by XBOOLE_0:def 1;
  reconsider y as Element of X by A1;
  Top L >= y by YELLOW_0:45;
  hence thesis by WAYBEL_0:def 20;
end;
