Lebesgue type inequalities for the de la Vallée Poussin sums and their interpolation analogues on classes of $(\psi,\bar{\beta})$-differentiable functions

Abstract

We obtain the estimates of norm of deviations of the de Vall\'{e}e Poussin sums and interpolation analogues of sums of Vall\'{e}e Poussin from the functions that belong to the space $C_{\bar{\beta}}^\psi L_s, \ 1\leq s\leq\infty$ and are represented by the best approximations of $(\psi,\bar{\beta})$-differentiable functions of this sort by trigonometric polynomials in the metric $L_s$