Comment on arXiv:0811.1575 entitled "Quantum phase transitions in the   Hubbard model on triangular lattice" by T. Yoshioka, A. Koga and N. Kawakami
  We show that the phase boundary between the paramagnetic metal and the nonmagnetic Mott insulator for the Hubbard model on a triangular lattice obtained by Yoshioka et al. in arXiv:0811.1575 does not correctly represent that of the thermodynamic limit but is an artifact of the 6 by 6 lattice they rely on. After the system size extrapolation, the phase boundary is located at U/t=5.2 as proposed by Morita et al., J. Phys. Soc. Jpn. 71 (2008) 2109 and in contrast to Yoshioka et al. Here, U is the onsite Coulomb repulsion and t is the nearest-neighbor transfer. 
Shinji Watanabe, Takahiro Mizusaki and Masatoshi Imada