 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  :: Theorem 3.7. (1) <=> (2)
  (x "/\" y) "\/" x = x iff x "/\" (y "\/" x) = x by Th3712;
