  An approximate partition functional is derived for the infinite-dimensional
Hubbard model. This functional naturally includes the exact solution of the
Falicov-Kimball model as a special case, and is exact in the uncorrelated and
atomic limits. It explicitly keeps spin-symmetry. For the case of the
Lorentzian density of states, we find that the Luttinger theorem is satisfied
at zero temperature. The susceptibility crosses over smoothly from that
expected for an uncorrelated state with antiferromagnetic fluctuations at high
temperature to a correlated state at low temperature via a Kondo-type anomaly
at a characteristic temperature $T^\star$. We attribute this anomaly to the
appearance of the Hubbard pseudo-gap. The specific heat also shows a peak near
$T^\star$. The resistivity goes to zero at zero temperature, in contrast to
other approximations, rises sharply around $T^\star$ and has a rough linear
temperature dependence above $T^\star$.
