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

theorem Th7:
  the carrier of latt B_6 = { 0, 1, 3 \ 1, 2, 3 \ 2, 3 }
proof
  the RelStr of B_6 = LattPOSet latt B_6 by LATTICE3:def 15;
  hence thesis by YELLOW_1:1;
end;
