APPROXIMATION OF THE DIFFERENTIATION OPERATOR ON THE CLASS OF FUNCTIONS ANALYTIC IN AN ANNULUS

In the class of functions analytic in the annulus \(C_r:=\left\{z\in\mathbb{C}\, :\, r<|z|<1\right\}\) with bounded \(L^p\)-norms on the unit circle, we study the problem of the best approximation of the operator taking the nontangential limit boundary values of a function on the circle \(\Gam...

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Main Author: Roman R. Akopyan
Format: Article
Language:English
Published: Ural Branch of the Russian Academy of Sciences and Ural Federal University named after the first President of Russia B.N.Yeltsin, Krasovskii Institute of Mathematics and Mechanics 2017-12-01
Series:Ural Mathematical Journal
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Online Access:https://umjuran.ru/index.php/umj/article/view/98
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author Roman R. Akopyan
author_facet Roman R. Akopyan
author_sort Roman R. Akopyan
collection DOAJ
description In the class of functions analytic in the annulus \(C_r:=\left\{z\in\mathbb{C}\, :\, r<|z|<1\right\}\) with bounded \(L^p\)-norms on the unit circle, we study the problem of the best approximation of the operator taking the nontangential limit boundary values of a function on the circle \(\Gamma_r\) of radius \(r\) to values of the derivative of the function on the circle \(\Gamma_\rho\) of radius \(\rho,\, r<\rho<1,\) by bounded linear operators from \(L^p(\Gamma_r)\) to \(L^p(\Gamma_ \rho)\) with norms not exceeding a number \(N\).  A solution of the problem has been obtained in the case when \(N\) belongs to the union of a sequence of intervals. The related problem of optimal recovery of the derivative of a function from boundary values of the function on \(\Gamma_\rho\) given with an error has been solved.
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institution Matheson Library
issn 2414-3952
language English
publishDate 2017-12-01
publisher Ural Branch of the Russian Academy of Sciences and Ural Federal University named after the first President of Russia B.N.Yeltsin, Krasovskii Institute of Mathematics and Mechanics
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series Ural Mathematical Journal
spelling doaj-art-1210b51f7a4b475dbed5135d4a1cee872025-07-02T02:13:31ZengUral Branch of the Russian Academy of Sciences and Ural Federal University named after the first President of Russia B.N.Yeltsin, Krasovskii Institute of Mathematics and MechanicsUral Mathematical Journal2414-39522017-12-013210.15826/umj.2017.2.00243APPROXIMATION OF THE DIFFERENTIATION OPERATOR ON THE CLASS OF FUNCTIONS ANALYTIC IN AN ANNULUSRoman R. Akopyan0Ural Federal University; Krasovskii Institute of Mathematics and Mechanics, Ural Branch of the Russian Academy of Sciences, EkaterinburgIn the class of functions analytic in the annulus \(C_r:=\left\{z\in\mathbb{C}\, :\, r<|z|<1\right\}\) with bounded \(L^p\)-norms on the unit circle, we study the problem of the best approximation of the operator taking the nontangential limit boundary values of a function on the circle \(\Gamma_r\) of radius \(r\) to values of the derivative of the function on the circle \(\Gamma_\rho\) of radius \(\rho,\, r<\rho<1,\) by bounded linear operators from \(L^p(\Gamma_r)\) to \(L^p(\Gamma_ \rho)\) with norms not exceeding a number \(N\).  A solution of the problem has been obtained in the case when \(N\) belongs to the union of a sequence of intervals. The related problem of optimal recovery of the derivative of a function from boundary values of the function on \(\Gamma_\rho\) given with an error has been solved.https://umjuran.ru/index.php/umj/article/view/98Best approximation of operators, Optimal recovery, Analytic functions
spellingShingle Roman R. Akopyan
APPROXIMATION OF THE DIFFERENTIATION OPERATOR ON THE CLASS OF FUNCTIONS ANALYTIC IN AN ANNULUS
Ural Mathematical Journal
Best approximation of operators, Optimal recovery, Analytic functions
title APPROXIMATION OF THE DIFFERENTIATION OPERATOR ON THE CLASS OF FUNCTIONS ANALYTIC IN AN ANNULUS
title_full APPROXIMATION OF THE DIFFERENTIATION OPERATOR ON THE CLASS OF FUNCTIONS ANALYTIC IN AN ANNULUS
title_fullStr APPROXIMATION OF THE DIFFERENTIATION OPERATOR ON THE CLASS OF FUNCTIONS ANALYTIC IN AN ANNULUS
title_full_unstemmed APPROXIMATION OF THE DIFFERENTIATION OPERATOR ON THE CLASS OF FUNCTIONS ANALYTIC IN AN ANNULUS
title_short APPROXIMATION OF THE DIFFERENTIATION OPERATOR ON THE CLASS OF FUNCTIONS ANALYTIC IN AN ANNULUS
title_sort approximation of the differentiation operator on the class of functions analytic in an annulus
topic Best approximation of operators, Optimal recovery, Analytic functions
url https://umjuran.ru/index.php/umj/article/view/98
work_keys_str_mv AT romanrakopyan approximationofthedifferentiationoperatorontheclassoffunctionsanalyticinanannulus