Open AccessGeneralization of the Hardy-Littlewood theorem on Fourier series
Author(s) -
S. Bitimkhan,
AUTHOR_ID
Publication year - 2021
Publication title -
ķaraġandy universitetìnìn̦ habaršysy. matematika seriâsy
Language(s) - English
Resource type - Journals
eISSN - 2663-5011
pISSN - 2518-7929
DOI - 10.31489/2021m4/49-55
Subject(s) - fourier series , mathematics , hardy space , generalization , trigonometric series , series (stratigraphy) , lebesgue integration , pure mathematics , fourier inversion theorem , mathematical analysis , fourier transform , space (punctuation) , monotonic function , conjugate fourier series , fourier analysis , fractional fourier transform , short time fourier transform , paleontology , linguistics , philosophy , biology
In the theory of one-dimensional trigonometric series, the Hardy-Littlewood theorem on Fourier series with monotone Fourier coefficients is of great importance. Multidimensional versions of this theorem have been extensively studied for the Lebesgue space. Significant differences of the multidimensional variants in comparison with the one-dimensional case are revealed and the strengthening of this theorem is obtained. The Hardy-Littlewood theorem is also generalized for various function spaces and various types of monotonicity of the series coefficients. Some of these generalizations can be seen in works of M.F. Timan, M.I. Dyachenko, E.D. Nursultanov, S. Tikhonov. In this paper, a generalization of the Hardy-Littlewood theorem for double Fourier series of a function in the space L_qϕ(L_q)(0,2π]^2 is obtained.