Abstract:
We study three related extremal problems in the space H of functions analytic in the unit disk such that their boundary values on a part γ1 of the unit circle Γ belong to the space L∞ψ1(γ1) of functions essentially bounded on γ1 with weight ψ1 and their boundary values on the set γ0=Γ∖γ1 belong to the space L∞ψ0(γ0) with weight ψ0. More exactly, on the class Q of functions from H such that the norm L∞ψ0(γ0) of their boundary values on γ0 does not exceed one, we solve the problem of optimal recovery of an analytic function on a subset of the unit disk from its boundary values on γ1 specified approximately with respect to the norm L∞ψ1(γ1). We also study the problem of the optimal choice of the set γ1 under a given fixed value of its measure. The problem of the best approximation of the operator of analytic continuation from a part of the boundary by linear bounded operators is investigated.
Keywords:
optimal recovery of analytic functions, best approximation of unbounded operators, Szegő function.
Citation:
R. R. Akopyan, “Optimal recovery of a function analytic in a disk from approximately given values on a part of the boundary”, Trudy Inst. Mat. i Mekh. UrO RAN, 22, no. 4, 2016, 29–42; Proc. Steklov Inst. Math. (Suppl.), 300, suppl. 1 (2018), 25–37
\Bibitem{Ako16}
\by R.~R.~Akopyan
\paper Optimal recovery of a function analytic in a disk from approximately given values on a part of the boundary
\serial Trudy Inst. Mat. i Mekh. UrO RAN
\yr 2016
\vol 22
\issue 4
\pages 29--42
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\crossref{https://doi.org/10.21538/0134-4889-2016-22-4-29-42}
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\jour Proc. Steklov Inst. Math. (Suppl.)
\yr 2018
\vol 300
\issue , suppl. 1
\pages 25--37
\crossref{https://doi.org/10.1134/S0081543818020049}
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Linking options:
https://www.mathnet.ru/eng/timm1351
https://www.mathnet.ru/eng/timm/v22/i4/p29
This publication is cited in the following 2 articles:
R. R. Akopyan, “Analog of the Hadamard Theorem and Related Extremal Problems on the Class of Analytic Functions”, Proc. Steklov Inst. Math. (Suppl.), 315:1 (2021), S13–S26
R. R. Akopyan, “An analogue of the two-constants theorem and optimal recovery of analytic functions”, Sb. Math., 210:10 (2019), 1348–1360