Abstract:
We give a solution of the problem on the best uniform approximation on the number axis of the first-order differentiation operator on the class of functions with bounded second derivative by linear operators bounded in the space $L_2$. This is one of the few cases of the exact solution of the problem on the approximation of the differentiation operator in some space with the use of approximating operators that are bounded in another space. We obtain a related exact inequality between the uniform norm of the derivative of a function, the variation of the Fourier transform of the function, and the $L_\infty$-norm of its second derivative. This inequality can be regarded as a nonclassical variant of the Hadamard–Kolmogorov inequality.
This work was supported by the Russian Foundation for Basic Research (project no. 18-01-00336) and by the Russian Academic Excellence Project (agreement no. 02.A03.21.0006 of August 27, 2013, between the Ministry of Education and Science of the Russian Federation and Ural Federal University).
Citation:
V. V. Arestov, “Best Uniform Approximation of the Differentiation Operator by Operators Bounded in the Space $L_2$”, Trudy Inst. Mat. i Mekh. UrO RAN, 24, no. 4, 2018, 34–56; Proc. Steklov Inst. Math. (Suppl.), 308, suppl. 1 (2020), S9–S30
\Bibitem{Are18}
\by V.~V.~Arestov
\paper Best Uniform Approximation of the Differentiation Operator by Operators Bounded in the Space~$L_2$
\serial Trudy Inst. Mat. i Mekh. UrO RAN
\yr 2018
\vol 24
\issue 4
\pages 34--56
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\crossref{https://doi.org/10.21538/0134-4889-2018-24-4-34-56}
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\transl
\jour Proc. Steklov Inst. Math. (Suppl.)
\yr 2020
\vol 308
\issue , suppl. 1
\pages S9--S30
\crossref{https://doi.org/10.1134/S0081543820020029}
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Linking options:
https://www.mathnet.ru/eng/timm1573
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This publication is cited in the following 10 articles:
K. Yu. Osipenko, “On the construction of families of optimal recovery methods for linear operators”, Izv. Math., 88:1 (2024), 92–113
Vitalii V. Arestov, “Approximation of differentiation operators by bounded linear operators in lebesgue spaces on the axis and related problems in the spaces of $(p,q)$-multipliers and their predual spaces”, Ural Math. J., 9:2 (2023), 4–27
V. V. Arestov, “Predual Spaces for the Space of (p, q)-Multipliers and Their Application in Stechkin's Problem on Approximation of Differentiation Operators”, Anal Math, 49:1 (2023), 43
K. Yu. Osipenko, “Optimal recovery in weighted spaces with homogeneous weights”, Sb. Math., 213:3 (2022), 385–411
I. V. Boykov, N. P. Krivulin, “An Approximate Method for Recovering Input Signals of Measurement Transducers”, Meas Tech, 64:12 (2022), 943
P. G. Surkov, “Approximate calculation of the Caputo-type fractional derivative from inaccurate data. Dynamical approach”, Fract. Calc. Appl. Anal., 24:3 (2021), 895–922
V. V. Arestov, R. R. Akopyan, “Zadacha Stechkina o nailuchshem priblizhenii neogranichennogo operatora ogranichennymi i rodstvennye ei zadachi”, Tr. IMM UrO RAN, 26, no. 4, 2020, 7–31
R. R. Akopyan, “Optimal recovery of a derivative of an analytic function from values of the function given with an error on a part of the boundary. II”, Anal. Math., 46:3 (2020), 409–424
V. Arestov, “Uniform approximation of differentiation operators by bounded linear operators in the spacel(r)”, Anal. Math., 46:3 (2020), 425–445
V. V. Arestov, “Best approximation of a differentiation operator on the set of smooth functions with exactly or approximately given Fourier transform”, Mathematical Optimization Theory and Operations Research, Lecture Notes in Computer Science, 11548, eds. M. Khachay, Y. Kochetov, P. Pardalos, Springer, 2019, 434–448