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JOURNALS // Izvestiya Rossiiskoi Akademii Nauk. Seriya Matematicheskaya // Archive

Izv. Akad. Nauk SSSR Ser. Mat., 1990 Volume 54, Issue 2, Pages 418–430 (Mi im1101)

This article is cited in 24 papers

Kolmogorov widths of classes of periodic functions of one and several variables

È. M. Galeev


Abstract: The order of Kolmogorov widths $d_N(\widetilde W_{\bar p}^{\bar\alpha},\widetilde L_q)$ are determined for the class $\widetilde W_{\bar p}^{\bar\alpha}=\bigcap\limits_{i=1}^m\widetilde W_{p^i}^{\alpha^i}$ that is the intersection of classes of periodic functions of one variable of “higher” smoothness, in the space $\widetilde L_q$ for $1<q<\infty$, and estimates from above for “low” smoothness, and also the order of Kolmogorov widths $d_N(\widetilde H_p^r,\widetilde L_q)$ is calculated for periodic functions of several variables in the space $\widetilde L_q$ for $1<p\leqslant q\leqslant 2$. The estimate from below for $d_N(\widetilde H_p^r,\widetilde L_q)$ reduces to the estimate from below of the width of a finite-dimensional set whose width is determined.

UDC: 517.5

MSC: Primary 41A25, 41A46; Secondary 42B99

Received: 07.06.1988


 English version:
Mathematics of the USSR-Izvestiya, 1991, 36:2, 435–448

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© Steklov Math. Inst. of RAS, 2024