Comment on "Symmetry properties of magnetization in the Hubbard model at   finite temperature"
  The results of G. Su and M. Suzuki [Phys. Rev. B 54, 8291 (1996); ibidem 57, 13367 (1998)] for the spin and pseudo-spin symmetry properties of the Hubbard model are reexamined. We point out that the exact relations they have found are valid down to zero temperature and that their solutions for both spin and pseudo-spin correlation functions are incorrect. 
A. Avella, F. Mancini and D. Villani (University of Salerno, Italy)