On Copson’s inequalities for 0 < p < 1 $0< p<1$

Abstract Let ( λ n ) n ≥ 1 $(\lambda_{n})_{n \geq1}$ be a positive sequence and let Λ n = ∑ i = 1 n λ i $\varLambda_{n}=\sum^{n}_{i=1}\lambda_{i}$ . We study the following Copson inequality for 0 < p < 1 $0< p<1$ , L > p $L>p$ : ∑ n = 1 ∞ ( 1 Λ n ∑ k = n ∞ λ k x k ) p ≥ ( p L − p )...

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Main Authors: Peng Gao, HuaYu Zhao
Format: Article
Language:English
Published: SpringerOpen 2020-03-01
Series:Journal of Inequalities and Applications
Subjects:
Online Access:http://link.springer.com/article/10.1186/s13660-020-02339-3
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author Peng Gao
HuaYu Zhao
author_facet Peng Gao
HuaYu Zhao
author_sort Peng Gao
collection DOAJ
description Abstract Let ( λ n ) n ≥ 1 $(\lambda_{n})_{n \geq1}$ be a positive sequence and let Λ n = ∑ i = 1 n λ i $\varLambda_{n}=\sum^{n}_{i=1}\lambda_{i}$ . We study the following Copson inequality for 0 < p < 1 $0< p<1$ , L > p $L>p$ : ∑ n = 1 ∞ ( 1 Λ n ∑ k = n ∞ λ k x k ) p ≥ ( p L − p ) p ∑ n = 1 ∞ x n p . $$\begin{aligned} \sum^{\infty}_{n=1} \Biggl(\frac{1}{\varLambda_{n}} \sum^{\infty }_{k=n}\lambda_{k} x_{k} \Biggr)^{p} \geq \biggl( \frac{p}{L-p} \biggr)^{p} \sum^{\infty}_{n=1}x^{p}_{n}. \end{aligned}$$ We find conditions on λ n $\lambda_{n}$ such that the above inequality is valid with the constant being the best possible.
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spelling doaj.art-a1bcc13d38024ef8ae7e339a8fa711252022-12-22T01:57:55ZengSpringerOpenJournal of Inequalities and Applications1029-242X2020-03-012020111310.1186/s13660-020-02339-3On Copson’s inequalities for 0 < p < 1 $0< p<1$Peng Gao0HuaYu Zhao1Department of Mathematics, School of Mathematical Sciences, Beihang UniversityAcademy of Mathematics and Systems Science, Chinese Academy of SciencesAbstract Let ( λ n ) n ≥ 1 $(\lambda_{n})_{n \geq1}$ be a positive sequence and let Λ n = ∑ i = 1 n λ i $\varLambda_{n}=\sum^{n}_{i=1}\lambda_{i}$ . We study the following Copson inequality for 0 < p < 1 $0< p<1$ , L > p $L>p$ : ∑ n = 1 ∞ ( 1 Λ n ∑ k = n ∞ λ k x k ) p ≥ ( p L − p ) p ∑ n = 1 ∞ x n p . $$\begin{aligned} \sum^{\infty}_{n=1} \Biggl(\frac{1}{\varLambda_{n}} \sum^{\infty }_{k=n}\lambda_{k} x_{k} \Biggr)^{p} \geq \biggl( \frac{p}{L-p} \biggr)^{p} \sum^{\infty}_{n=1}x^{p}_{n}. \end{aligned}$$ We find conditions on λ n $\lambda_{n}$ such that the above inequality is valid with the constant being the best possible.http://link.springer.com/article/10.1186/s13660-020-02339-3Copson’s inequalities
spellingShingle Peng Gao
HuaYu Zhao
On Copson’s inequalities for 0 < p < 1 $0< p<1$
Journal of Inequalities and Applications
Copson’s inequalities
title On Copson’s inequalities for 0 < p < 1 $0< p<1$
title_full On Copson’s inequalities for 0 < p < 1 $0< p<1$
title_fullStr On Copson’s inequalities for 0 < p < 1 $0< p<1$
title_full_unstemmed On Copson’s inequalities for 0 < p < 1 $0< p<1$
title_short On Copson’s inequalities for 0 < p < 1 $0< p<1$
title_sort on copson s inequalities for 0 p 1 0 p 1
topic Copson’s inequalities
url http://link.springer.com/article/10.1186/s13660-020-02339-3
work_keys_str_mv AT penggao oncopsonsinequalitiesfor0p10p1
AT huayuzhao oncopsonsinequalitiesfor0p10p1