HUBBARD-MODEL, CONSERVED QUANTITIES, AND COMPUTER ALGEBRA

The constants of motion of the half-filled four-point Hubbard model wi th cyclic boundary conditions are given in Wannier and Bloch represent ation. The total number operator and total spin operator are conserved and spin-reversal symmetry exists. In Wannier representation we have additionally the C4v symmetry and in Bloch representation we have the total momentum operator which is conserved. The anticommutation relati ons for Fermi operators with spin are implemented using computer algeb ra. Using computer algebra, all the constants of motion are given. The one-dimensional Hubbard model admits a Lax representation. From the L ax pair we find a new constant of motion.