reserve L for Lattice,
  p,q,r for Element of L,
  p9,q9,r9 for Element of L.:,
  x, y for set;

theorem
  for L1,L2 being non empty LattStr st the LattStr of L1 = the LattStr
of L2 for a1,b1 being Element of L1, a2,b2 being Element of L2 st a1 = a2 & b1
= b2 holds a1"\/"b1 = a2"\/"b2 & a1"/\"b1 = a2"/\"b2 & (a1 [= b1 iff a2 [= b2);
