  Using the Dirac-Brueckner-Hartree-Fock approach, the properties of
neutron-star matter including hyperons are investigated. In the calculation, we
consider both time and space components of the vector self-energies of baryons
as well as the scalar ones. Furthermore, the effect of negative-energy states
of baryons is partly taken into account. We obtain the maximum neutron-star
mass of $2.08\,M_{\odot}$, which is consistent with the recently observed,
massive neutron stars. We discuss a universal, repulsive three-body force for
hyperons in matter.
