 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) <=> (5)
  (x "/\" y) "\/" x = x iff x "/\" y = y "/\" x by Th3715,LATTICES:def 8;
