Lebesgue's Differentiation Theorems in R.I. Quasi-Banach Spaces and Lorentz Spaces Γp,w

The paper is devoted to investigation of new Lebesgue's type differentiation theorems (LDT) in rearrangement invariant (r.i.) quasi-Banach spaces E and in particular on Lorentz spaces Γp,w={f:∫(f**)pw<∞} for any 0<p<∞ and a nonnegative locally integrable weight function w, where f** is...

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Main Authors: Maciej Ciesielski, Anna Kamińska
Format: Article
Language:English
Published: Wiley 2012-01-01
Series:Journal of Function Spaces and Applications
Online Access:http://dx.doi.org/10.1155/2012/682960
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author Maciej Ciesielski
Anna Kamińska
author_facet Maciej Ciesielski
Anna Kamińska
author_sort Maciej Ciesielski
collection DOAJ
description The paper is devoted to investigation of new Lebesgue's type differentiation theorems (LDT) in rearrangement invariant (r.i.) quasi-Banach spaces E and in particular on Lorentz spaces Γp,w={f:∫(f**)pw<∞} for any 0<p<∞ and a nonnegative locally integrable weight function w, where f** is a maximal function of the decreasing rearrangement f* for any measurable function f on (0,α), with 0<α≤∞. The first type of LDT in the spirit of Stein (1970), characterizes the convergence of quasinorm averages of f∈E, where E is an order continuous r.i. quasi-Banach space. The second type of LDT establishes conditions for pointwise convergence of the best or extended best constant approximants fϵ of f∈Γp,w or f∈Γp-1,w, 1<p<∞, respectively. In the last section it is shown that the extended best constant approximant operator assumes a unique constant value for any function f∈Γp-1,w, 1<p<∞.
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spelling doaj-art-49fd8f9e3f914c31bcfeed12ae84b4332025-02-03T05:50:48ZengWileyJournal of Function Spaces and Applications0972-68021758-49652012-01-01201210.1155/2012/682960682960Lebesgue's Differentiation Theorems in R.I. Quasi-Banach Spaces and Lorentz Spaces Γp,wMaciej Ciesielski0Anna Kamińska1Institute of Mathematics, Poznań University of Technology, Piotrowo 3a, 60-965 Poznań, PolandDepartment of Mathematical Sciences, The University of Memphis, Memphis, TN 38152, USAThe paper is devoted to investigation of new Lebesgue's type differentiation theorems (LDT) in rearrangement invariant (r.i.) quasi-Banach spaces E and in particular on Lorentz spaces Γp,w={f:∫(f**)pw<∞} for any 0<p<∞ and a nonnegative locally integrable weight function w, where f** is a maximal function of the decreasing rearrangement f* for any measurable function f on (0,α), with 0<α≤∞. The first type of LDT in the spirit of Stein (1970), characterizes the convergence of quasinorm averages of f∈E, where E is an order continuous r.i. quasi-Banach space. The second type of LDT establishes conditions for pointwise convergence of the best or extended best constant approximants fϵ of f∈Γp,w or f∈Γp-1,w, 1<p<∞, respectively. In the last section it is shown that the extended best constant approximant operator assumes a unique constant value for any function f∈Γp-1,w, 1<p<∞.http://dx.doi.org/10.1155/2012/682960
spellingShingle Maciej Ciesielski
Anna Kamińska
Lebesgue's Differentiation Theorems in R.I. Quasi-Banach Spaces and Lorentz Spaces Γp,w
Journal of Function Spaces and Applications
title Lebesgue's Differentiation Theorems in R.I. Quasi-Banach Spaces and Lorentz Spaces Γp,w
title_full Lebesgue's Differentiation Theorems in R.I. Quasi-Banach Spaces and Lorentz Spaces Γp,w
title_fullStr Lebesgue's Differentiation Theorems in R.I. Quasi-Banach Spaces and Lorentz Spaces Γp,w
title_full_unstemmed Lebesgue's Differentiation Theorems in R.I. Quasi-Banach Spaces and Lorentz Spaces Γp,w
title_short Lebesgue's Differentiation Theorems in R.I. Quasi-Banach Spaces and Lorentz Spaces Γp,w
title_sort lebesgue s differentiation theorems in r i quasi banach spaces and lorentz spaces γp w
url http://dx.doi.org/10.1155/2012/682960
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AT annakaminska lebesguesdifferentiationtheoremsinriquasibanachspacesandlorentzspacesgpw