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JOURNALS // Matematicheskii Sbornik // Archive

Mat. Sb., 2025 Volume 216, Number 3, Pages 108–127 (Mi sm10231)

Sequences of partial sums of multiple trigonometric Fourier series

S. V. Konyaginab

a Steklov Mathematical Institute of Russian Academy of Sciences, Moscow, Russia
b Faculty of Mechanics and Mathematics, Lomonosov Moscow State University, Moscow, Russia

Abstract: Let $f$ be an integrable $2\pi$-periodic function of $d\ge2$ variables. For a bounded subset $A$ of the $d$-dimensional space let $S_A(f)$ denote the sum of terms of the Fourier series of $f$ with frequencies in $A$. The following problem is addressed: given a sequence $\{A_j\}$ of bounded convex sets, do there exist a function $f$ and a sequence $\{j_\nu\}$ such that $\lim_{\nu\to\infty} |S_{A_{j_\nu}} (f)|=\infty$ almost everywhere?
Bibliography: 5 titles.

Keywords: convergence of multiple trigonometric Fourier series, convex set, lattice.

MSC: 42B05, 42B08

Received: 04.11.2024

DOI: 10.4213/sm10231


 English version:
Sbornik: Mathematics, 2025, 216:3, 368–385

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© Steklov Math. Inst. of RAS, 2025