@article{Romanyuk_2018, title={Kolmogorov widths and bilinear approximations of the classes of periodic
functions of one and many variables}, volume={70}, url={http://umj.imath.kiev.ua/index.php/umj/article/view/1553}, abstractNote={We obtain the exact order estimates for the Kolmogorov widths of the classes $W^g_p$ of periodic functions of one variable generated by the integral operators with kernels $g(x, y)$ from the Nikol’skii – Besov classes $B^r_{p,\theta}$. We also study the
behavior of bilinear approximations to the classes $W^r_{p,\alpha}$ of periodic multivariate functions with bounded mixed derivative
in the spaces $L_{q_1,q_2}$ for some relations between the parameters $r_1, p, q_1, q_2$.}, number={2}, journal={Ukrains’kyi Matematychnyi Zhurnal}, author={RomanyukA. S.}, year={2018}, month={Feb.}, pages={224-235} }