Sharp Hardy's Inequalities in Hilbert Spaces

Fuente: arXiv
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Auteurs principaux: Dimitrov, Dimitar K., Gadjev, Ivan, Ismail, Mourad E. H.
Format: Preprint
Publié: 2023
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author Dimitrov, Dimitar K.
Gadjev, Ivan
Ismail, Mourad E. H.
author_facet Dimitrov, Dimitar K.
Gadjev, Ivan
Ismail, Mourad E. H.
contents We study the behavior of the smallest possible constants $d(a,b)$ and $d_n$ in Hardy's inequalities $$ \int_a^b\left(\frac{1}{x}\int_a^xf(t)dt\right)^2\,dx\leq d(a,b)\,\int_a^b [f(x)]^2 dx $$ and $$ \sum_{k=1}^{n}\Big(\frac{1}{k}\sum_{j=1}^{k}a_j\Big)^2\leq d_n\,\sum_{k=1}^{n}a_k^2. $$ The exact constant $d(a,b)$ and the precise rate of convergence of $d_n$ are established and the extremal function and the ``almost extremal'' sequence are found.
format Preprint
id arxiv_https___arxiv_org_abs_2306_08172
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Sharp Hardy's Inequalities in Hilbert Spaces
Dimitrov, Dimitar K.
Gadjev, Ivan
Ismail, Mourad E. H.
Classical Analysis and ODEs
Primary 26D10, 26D15, Secondary 33D45
We study the behavior of the smallest possible constants $d(a,b)$ and $d_n$ in Hardy's inequalities $$ \int_a^b\left(\frac{1}{x}\int_a^xf(t)dt\right)^2\,dx\leq d(a,b)\,\int_a^b [f(x)]^2 dx $$ and $$ \sum_{k=1}^{n}\Big(\frac{1}{k}\sum_{j=1}^{k}a_j\Big)^2\leq d_n\,\sum_{k=1}^{n}a_k^2. $$ The exact constant $d(a,b)$ and the precise rate of convergence of $d_n$ are established and the extremal function and the ``almost extremal'' sequence are found.
title Sharp Hardy's Inequalities in Hilbert Spaces
topic Classical Analysis and ODEs
Primary 26D10, 26D15, Secondary 33D45
url https://arxiv.org/abs/2306.08172