Generalized Fokker–Planck equation and construction of projection operators for different methods of reduced description of nonequilibrium states

A method is proposed for constructing generalized Fokker–Planck equations by means of projection into the space of “coarse” variables, the form of the projection operator being determined by the condition of correspondence with the nonequilibrium statistical operator method. Examples are given of the construction of the projection operators for different methods of reduced description of the nonequilibrium state.