EXACT RESULTS FOR THE U = INFINITY HUBBARD-MODEL

Several rigorous results are obtained for the U= Hubbard model, including a lower bound on the energy for any finite number of holes relative to half filling. The bound implies that the ferromagnetic state becomes asymptotically degenerate with the exact ground state in the thermodynamic limit, and that added holes do not form bound states. An alternate derivation of Nagaokas theorem is obtained. © 1990 The American Physical Society.