  Using exact diagonalization calculations, we investigate the ground-state
phase diagram of the hard-core Bose-Hubbard-Haldane model on the honeycomb
lattice. This allows us to probe the stability of the Bose-metal phase proposed
in Varney et al (2011 Phys. Rev. Lett. 107 077201), against various changes in
the originally studied Hamiltonian.
