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

theorem Th11:
  for L1,L2 being C_Lattice 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 & a1 is_a_complement_of b1 holds a2 is_a_complement_of b2
by Th9,Th10;
