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Main Authors: Fraccaroli, Marco, Kosz, Dariusz, Roncal, Luz
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2505.05425
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author Fraccaroli, Marco
Kosz, Dariusz
Roncal, Luz
author_facet Fraccaroli, Marco
Kosz, Dariusz
Roncal, Luz
contents We study the problem of differentiation of integrals for certain bases in the infinite-dimensional torus $\mathbb{T}^ω$. In particular, for every $p_0 \in [1,\infty)$, we construct a basis $\mathcal{B}$ which differentiates $L^p(\mathbb{T}^ω)$ if and only if $p \geq p_0$, thus reproving classical theorems of Hayes in $\mathbb{R}$. The main novelty is that our $\mathcal{B}$ is a Busemann--Feller basis consisting of rectangles (of arbitrarily large dimensions) with sides parallel to the coordinate axes. Our construction gives us the opportunity to classify all possible ranges of differentiation for general complete spaces. Namely, let $\mathcal{B}$ be a basis in a metric measure space $\mathcal{X}$. If $\mathcal{X}$ is complete, then the set $\{ p \in [1,\infty] : \mathcal{B} \text{ differentiates } L^p(\mathcal{X}) \}$ takes one of the six forms\[ \emptyset, \, \{\infty\}, \, [p_0,\infty], \, (p_0,\infty], \, [p_0,\infty), \, (p_0,\infty) \quad \text{for some} \quad p_0 \in [1,\infty). \] Conversely, for every $p_0 \in [1,\infty)$ and each of the six cases above, we construct a complete space $\mathcal{X}$ and a basis $\mathcal{B}$ illustrating the corresponding range of differentiation.
format Preprint
id arxiv_https___arxiv_org_abs_2505_05425
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On differentiation of integrals in Lebesgue spaces
Fraccaroli, Marco
Kosz, Dariusz
Roncal, Luz
Classical Analysis and ODEs
Primary 43A75, 42B25
We study the problem of differentiation of integrals for certain bases in the infinite-dimensional torus $\mathbb{T}^ω$. In particular, for every $p_0 \in [1,\infty)$, we construct a basis $\mathcal{B}$ which differentiates $L^p(\mathbb{T}^ω)$ if and only if $p \geq p_0$, thus reproving classical theorems of Hayes in $\mathbb{R}$. The main novelty is that our $\mathcal{B}$ is a Busemann--Feller basis consisting of rectangles (of arbitrarily large dimensions) with sides parallel to the coordinate axes. Our construction gives us the opportunity to classify all possible ranges of differentiation for general complete spaces. Namely, let $\mathcal{B}$ be a basis in a metric measure space $\mathcal{X}$. If $\mathcal{X}$ is complete, then the set $\{ p \in [1,\infty] : \mathcal{B} \text{ differentiates } L^p(\mathcal{X}) \}$ takes one of the six forms\[ \emptyset, \, \{\infty\}, \, [p_0,\infty], \, (p_0,\infty], \, [p_0,\infty), \, (p_0,\infty) \quad \text{for some} \quad p_0 \in [1,\infty). \] Conversely, for every $p_0 \in [1,\infty)$ and each of the six cases above, we construct a complete space $\mathcal{X}$ and a basis $\mathcal{B}$ illustrating the corresponding range of differentiation.
title On differentiation of integrals in Lebesgue spaces
topic Classical Analysis and ODEs
Primary 43A75, 42B25
url https://arxiv.org/abs/2505.05425