It is shown that the dynamics of a single ↓-electron interacting
with a band of ↑-electrons can be calculated exactly in the limit of
infinite dimension. The corresponding Green function is determined as a
continued fraction. It is used to investigate the stability of saturated
ferromagnetism and the nature of the ground state for two generic non-bipartite
infinite dimensional lattices. Non Fermi liquid behavior is found. For certain
dopings the ↓-electron is bound to the ↑-holes.Comment: 4 pages, 3 figures included with psfig, Revtex; Phys. Rev. Lett. in
press; some amendments made to clarify the calculation of the self-energy,
the extrapolation of the continued fraction, and the statements on
Fermi-liquid theor