Lower bounds for widths of classes of convolutions of periodic functions in the metrics of $C$ and $L$

We give new sufficient conditions for kernels to belong to the set $C_{y, 2n}$ introduced by Kushpel'. These conditions give the possibility of extending the set of kernels belonging to $C_{y, 2n}$. On the basis of these results, we obtain lower bounds for the Kolmogorov widths of classes o...

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Bibliographic Details
Date:1995
Main Authors: Serdyuk, A. S., Stepanets, O. I., Сердюк, А. С., Степанец, А. И.
Format: Article
Language:Russian
Published: Institute of Mathematics, NAS of Ukraine 1995
Online Access:https://umj.imath.kiev.ua/index.php/umj/article/view/5507
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Journal Title:Ukrains’kyi Matematychnyi Zhurnal
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Ukrains’kyi Matematychnyi Zhurnal
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Summary:We give new sufficient conditions for kernels to belong to the set $C_{y, 2n}$ introduced by Kushpel'. These conditions give the possibility of extending the set of kernels belonging to $C_{y, 2n}$. On the basis of these results, we obtain lower bounds for the Kolmogorov widths of classes of convolutions with these kernels. We show that these estimates are exact in certain important cases.