A method of solving infinite systems of equations for two-time thermal Green's functions

An infinite system of coupled equations of Dyson type is constructed for the two-time correlation functions and Green's functions in which the two-particle, threeparticle, etc., scattering is taken into account successively at each stage. Explicit expressions are obtained for the correlation functions with projected evolution that occur in the mass operators of the equations. The method developed in the paper is compared with the methods based on the introduction of a projection operator.