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Mat. Zametki, 2016 Volume 99, Issue 2, Pages 186–200 (Mi mzm10503)

Equiconvergence of Expansions in Multiple Fourier Series and in Fourier Integrals with “Lacunary Sequences of Partial Sums”

I. L. Bloshanskii, D. A. Grafov

Moscow State Region University

Abstract: We investigate the equiconvergence on $\mathbb T^N=[-\pi,\pi)^N$ of expansions in multiple trigonometric Fourier series and in the Fourier integrals of functions $f\in L_p({\mathbb T}^N)$ and $g\in L_p({\mathbb R}^N)$, $p>1$, $N\ge 3$, $g(x)=f(x)$ on $\mathbb T^N$, in the case where the “partial sums” of these expansions, i.e., $S_n(x;f)$ and $J_\alpha(x;g)$, respectively, have “numbers” $n\in {\mathbb Z}^N$ and $\alpha\in {\mathbb R}^N$ ($n_j=[\alpha_j]$, $j=1,\dots,N$, $[t]$ is the integral part of $t\in \mathbb R^1$) containing $N-1$ components which are elements of “lacunary sequences.”

Keywords: multiple Fourier series, multiple Fourier integrals, convergence almost everywhere, lacunary sequence.

UDC: 517.518.4+517.518.5

Received: 10.03.2014
Revised: 04.10.2014

DOI: 10.4213/mzm10503


 English version:
Mathematical Notes, 2016, 99:2, 196–209

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