 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
  for a,b being Element of L,
      x,y being Element of LatRelStr L st
    a = x & b = y holds
    x <= y iff a [= b by OrdLat,ORDERS_2:def 5;
