Sharpening the gap between $L^{1}$ and $L^{2}$ norms

Fuente: arXiv
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Autori principali: Ivanisvili, Paata, Stone, Yonathan
Natura: Preprint
Pubblicazione: 2024
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author Ivanisvili, Paata
Stone, Yonathan
author_facet Ivanisvili, Paata
Stone, Yonathan
contents We refine the classical Cauchy--Schwartz inequality $\|X\|_{1} \leq \|X\|_{2}$ by demonstrating that for any $p$ and $q$ with $q>p>2$, there exists a constant $C=C(p,q)$ such that $\|X\|_1 \leq 1 - C \Big{(}\|X\|_p^p - 1\Big{)}^{\frac{q-2}{q-p}}\Big{(}\|X\|_q^q - 1\Big{)}^{\frac{2-p}{q-p}}$ holds true for all Borel measurable random variables $X$ with $\|X\|_{2}=1$ and $\|X\|_{p}<\infty$. We illustrate two applications of this result: one for biased Rademacher sums and another for exponential sums.
format Preprint
id arxiv_https___arxiv_org_abs_2407_04835
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Sharpening the gap between $L^{1}$ and $L^{2}$ norms
Ivanisvili, Paata
Stone, Yonathan
Probability
Classical Analysis and ODEs
Differential Geometry
Functional Analysis
39B62
We refine the classical Cauchy--Schwartz inequality $\|X\|_{1} \leq \|X\|_{2}$ by demonstrating that for any $p$ and $q$ with $q>p>2$, there exists a constant $C=C(p,q)$ such that $\|X\|_1 \leq 1 - C \Big{(}\|X\|_p^p - 1\Big{)}^{\frac{q-2}{q-p}}\Big{(}\|X\|_q^q - 1\Big{)}^{\frac{2-p}{q-p}}$ holds true for all Borel measurable random variables $X$ with $\|X\|_{2}=1$ and $\|X\|_{p}<\infty$. We illustrate two applications of this result: one for biased Rademacher sums and another for exponential sums.
title Sharpening the gap between $L^{1}$ and $L^{2}$ norms
topic Probability
Classical Analysis and ODEs
Differential Geometry
Functional Analysis
39B62
url https://arxiv.org/abs/2407.04835