 reserve L for AD_Lattice;
 reserve x,y,z for Element of L;
 reserve L for GAD_Lattice;
 reserve x,y,z for Element of L;

theorem Lem36X:   :: Lemma 3.6. (1)
  x "\/" (x "\/" y) = x "\/" y
  proof
    x "/\" (x "\/" y) = x by LATTICES:def 9;
    hence thesis by LATTICES:def 8;
  end;
