On periodic solutions of countable systems of linear and quasilinear difference equations with periodic coefficients

Investigation of the Approximation of Continuous Periodic Functions on the Torus

“…attention of modern studies is paid to the distribution of the above-mentioned class of systems of results that take place for finite-dimensional systems of differential and difference equations [8,9]. A set of such functions forms a linear space, which will be further denoted as , such that the following equality is fulfilled…”