  It is shown that the BBGKY equations for a particle interacting with ideal
gas imply exact relations between probability distribution of path of the
particle, its derivatives in respect to the gas density and irreducible
many-particle correlations of gas atoms with the path. These relations
visualize that the correlations of any order always significantly contribute to
evolution of the path distribution, so that the exact statistical mechanics
theory does not reduce to the classical kinetics even in the low-density (or
Boltzmann-Grad) limit.
