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Lower bound for the best approximations of periodic summable functions of two variables and their conjugates in terms of Fourier coefficients

In terms of Fourier coefficients, we establish lower bounds for the sum of norms and the sum of the best approximations by trigonometric polynomials for functions from the space L(Q&sup2;) and functions conjugate to them with respect to each variable and with respect to both variables, provi...

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Bibliographic Details
Date:	2008
Main Authors:	Kononovych, T. O., Кононович, Т. О.
Format:	Article
Language:	Ukrainian English
Published:	Institute of Mathematics, NAS of Ukraine 2008
Online Access:	https://umj.imath.kiev.ua/index.php/umj/article/view/3222
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Journal Title:	Ukrains’kyi Matematychnyi Zhurnal
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