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 X \+\ Y
proof
  X "/\" Y misses X \ Y & X "/\" Y misses Y \ X by Th50;
  hence thesis by Th49;
end;
