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

theorem Th26:
  for a, x being Element of Benzene st a = 0 holds a "\/" x = x
proof
  let a, x be Element of Benzene;
  assume a = 0;
  then a c= x;
  then a [= x by Th24;
  hence thesis;
end;
