  The effective spin Hamiltonian is constructed in the framework of the almost
half-filled Hubbard model on the Cayley tree by means of functional integral
technique with the use of static approximation. The system in the ground state
appears to be consisting of the ferromagnetic metallic domains and the
antiferromagnetic insulating one sprovided that the concentration of excess
electrons (or holes) does not exceed some critical value. The connection
between the Hubbard model and the {\it s-f} model is stated. Note added: This
posting is intended to show that the phase separation in strongly correlated
electronic systems was considered already in 1970-80's and is not a discovery
of latest manganites boom
