On Approximations by Trigonometric Polynomials of Classes of Functions Defined by Moduli of Smoothness

In this paper, we give a characterization of Nikol’skiĭ-Besov type classes of functions, given by integral representations of moduli of smoothness, in terms of series over the moduli of smoothness. Also, necessary and sufficient conditions in terms of monotone or lacunary Fourier coefficients for a...

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Bibliographic Details
Main Authors: Nimete Sh. Berisha, Faton M. Berisha, Mikhail K. Potapov, Marjan Dema
Format: Article
Language:English
Published: Wiley 2017-01-01
Series:Abstract and Applied Analysis
Online Access:http://dx.doi.org/10.1155/2017/9323181
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Summary:In this paper, we give a characterization of Nikol’skiĭ-Besov type classes of functions, given by integral representations of moduli of smoothness, in terms of series over the moduli of smoothness. Also, necessary and sufficient conditions in terms of monotone or lacunary Fourier coefficients for a function to belong to such a class are given. In order to prove our results, we make use of certain recent reverse Copson-type and Leindler-type inequalities.
ISSN:1085-3375
1687-0409