Almost Everywhere Convergence of Arithmetic Means of Walsh--Fourier Partial Sums Along Subsequences

Fuente: arXiv
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Main Author: Goginava, Ushangi
Format: Preprint
Published: 2026
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author Goginava, Ushangi
author_facet Goginava, Ushangi
contents Let $S_m f$ denote the $m$-th partial sum of the Walsh-Fourier series of $f \in L^1$. For an increasing sequence $a=(a(n))_{n \geq 1}$ of positive integers, consider the arithmetic means $$ σ_N f:=\frac{1}{N} \sum_{n=1}^N S_{a(n)} f . $$ Gát proved in 2019 that $σ_N f \rightarrow f$ almost everywhere for every $f \in L^1$ under the growth condition $$ a(n+1) \geq\left(1+\frac{1}{n^δ}\right) a(n), \quad 0<δ<\frac{1}{2} . $$ We show that the same conclusion remains valid throughout the full range $0<δ<1$.
format Preprint
id arxiv_https___arxiv_org_abs_2605_05146
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Almost Everywhere Convergence of Arithmetic Means of Walsh--Fourier Partial Sums Along Subsequences
Goginava, Ushangi
Classical Analysis and ODEs
Let $S_m f$ denote the $m$-th partial sum of the Walsh-Fourier series of $f \in L^1$. For an increasing sequence $a=(a(n))_{n \geq 1}$ of positive integers, consider the arithmetic means $$ σ_N f:=\frac{1}{N} \sum_{n=1}^N S_{a(n)} f . $$ Gát proved in 2019 that $σ_N f \rightarrow f$ almost everywhere for every $f \in L^1$ under the growth condition $$ a(n+1) \geq\left(1+\frac{1}{n^δ}\right) a(n), \quad 0<δ<\frac{1}{2} . $$ We show that the same conclusion remains valid throughout the full range $0<δ<1$.
title Almost Everywhere Convergence of Arithmetic Means of Walsh--Fourier Partial Sums Along Subsequences
topic Classical Analysis and ODEs
url https://arxiv.org/abs/2605.05146