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JOURNALS // Itogi Nauki i Tekhniki. Sovremennaya Matematika i ee Prilozheniya. Tematicheskie Obzory // Archive

Itogi Nauki i Tekhniki. Sovrem. Mat. Pril. Temat. Obz., 2023 Volume 227, Pages 3–19 (Mi into1214)

On orders of $n$-term approximations of functions of many variables in the Lorentz space

G. A. Akishev

Kazakhstan Branch of Lomonosov Moscow State University, Nur-Sultan

Abstract: In this paper, we consider the anisotropic Lorentz space of $2\pi$-periodic functions of many variables and the Nikolsky–Besov class in this space. We obtain estimates for the best approximations along the hyperbolic cross and the best $M$-term approximations of functions of the Nikolsky—Besov class with respect to the norm of the anisotropic Lorentz space for various relations between the parameters of the class and the space.

Keywords: Lorentz space, trigonometric polynomial, best $M$-term approximation

UDC: 517.51

MSC: 41A10

DOI: 10.36535/0233-6723-2023-227-3-19



© Steklov Math. Inst. of RAS, 2025