theorem
  for L being 1_Lattice holds Top L = Bottom (L.:)
proof
  let L be 1_Lattice;
  reconsider u = Top L as Element of L.:;
  now
    let v be Element of L.:;
    reconsider v9 = v as Element of L;
    thus v "/\" u = Top L "\/" v9 by Th37
      .= u;
  end;
  hence thesis by RLSUB_2:64;
end;
