
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);
