Peculiarities of description of fermion system with many-body interaction by Green function method

General ratios between the Green functions of the fermion system with multiparticle interaction, under which a simultaneous interaction of three or more nucleons is meant, are obtained. A precise expression for the basic state energy through the values of many-body theory is more complicated as compared to the case with the system with two-particle interaction. On the other hand, the conditions for agreement between one-particle mass operator and nucleon-nucleon interaction amplitude, non-presented in the particle-hole channel, preserve their shape under activation of multiparticle interactions in the medium. 5 refs