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

theorem Th29:
  Bottom Benzene = 0
proof
  reconsider x = 0 as Element of Benzene by Th9,ENUMSET1:def 4;
  for a being Element of Benzene holds x "/\" a = x & a "/\" x = x by Th25;
  hence thesis by LATTICES:def 16;
end;
