reserve L for Ortholattice,
  a, b, c for Element of L;

theorem Th8:
  for a being set st a in the carrier of latt B_6 holds a c= Segm 3
proof
  let a be set;
  assume a in the carrier of latt B_6;
  then a = 0 or a = Segm 1 or a = 3 \ 1 or a = Segm 2 or a = 3 \ 2 or a = 3
     by Th7,ENUMSET1:def 4;
  hence thesis by NAT_1:39;
end;
