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

theorem
  Top Benzene = 3
proof
  reconsider x = 3 as Element of Benzene by Th9,ENUMSET1:def 4;
  for a being Element of Benzene holds x "\/" a = x & a "\/" x = x by Th27;
  hence thesis by LATTICES:def 17;
end;
