  A generalized supersymmetric representation of the Hubbard operator algebra
is considered. This representation is applied to the infinite-U Hubbard model.
A mean-field theory which takes into account both on-site and inter-site
virtual boson-fermion transitions is developed. Unlike previous approaches, the
mean-field theory considered is free from divergences. Possible application of
these results to the ferromagnet-paramagnet transition, as well as to other
problems is discussed.
