 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;
reserve L for with_zero GAD_Lattice,
        x,y for Element of L;

theorem   :: Lemma 3.15. (3)
  bottom L "\/" x = x
  proof
    bottom L "/\" x = bottom L by GADL0;
    hence thesis by LATTICES:def 8;
  end;
