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

theorem Th27:
  for a, x being Element of Benzene st a = 3 holds a "\/" x = a
proof
  let a, x be Element of Benzene;
  assume a = 3;
  then x c= a by Th11,YELLOW11:1;
  then x [= a by Th24;
  hence thesis;
end;
