reserve L for Lattice;
reserve X,Y,Z,V for Element of L;
reserve L for D_Lattice;
reserve X,Y,Z for Element of L;
reserve L for 0_Lattice;
reserve X,Y,Z for Element of L;
reserve L for B_Lattice;
reserve X,Y,Z,V for Element of L;

theorem
  (X \ Y) misses Y
proof
  (X \ Y) "/\" Y = X "/\" (Y` "/\" Y) by LATTICES:def 7
    .= X "/\" Bottom L by LATTICES:20
    .= Bottom L;
  hence thesis;
end;
