A discrete model for nonlinear problems of Radiation Transfer: principle of invariance and factorization

A discrete model for nonlinear problems of Radiation Transfer in a plane layer, consisting of finite or infinite number of identical sublayers, possessing given reflection-transmission properties, is considered. Fulfilment of condition of dissipativness or conservativness is assumed. Concept оf minimality of the solution provides uniqueness of solution of boundary value problem for the difference transfer equation. An a priori estimates are obtained. Ambartsumian Principle of Invariance is diseminated and substantiated on Transfer equation in half-space, which lead to factorization of nonlinear boundary-value problem.