Extension of a complete monotonicity theorem with applications

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Auteur principal: Yang, Zhen-Hang
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Publié: 2025
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_version_ 1866916844054511616
author Yang, Zhen-Hang
author_facet Yang, Zhen-Hang
contents Let $F_{p}(x) =L( t^{p}f(t)) =\int_{0}^{\infty }t^{p}f(t) e^{-xt}dt$ converge on $(0,\infty)$ for $p\in \mathbb{N}_{0}=\mathbb{N}\cup{0}$, where $f(t)$ is positive on $(0,\infty)$. In a recent paper [Z.-H. Yang, A complete monotonicity theorem related to Fink's inequality with applications, \emph{J. Math. Anal. Appl.} \textbf{551} (2025), no. 1, Paper no. 129600], the author proved the sufficient conditions for the function \begin{equation*} x\mapsto \prod_{j=1}^{n}F_{p_{j}}(x) -λ_{n}\prod_{j=1}^{n}F_{q_{j}}(x) \end{equation*} to be completely monotonic on $(0,\infty)$ by induction, where $\boldsymbol{p}_{[n] }=(p_{1},...,p_{n}) $ and $ \boldsymbol{q}_{[n] }=(q_{1},...,q_{n}) \in \mathbb{N }_{0}^{n}$ for $n\geq 2$ satisfy $\boldsymbol{p}_{[n] }\prec \boldsymbol{q}_{[n]}$ However, the proof of the inductive step is wrong. In this paper, we prove the above result also holds for $ \boldsymbol{p}_[n]},\boldsymbol{q}_{[n] }\in \mathbb{I}^{k}$, where $\mathbb{I}\subseteq \mathbb{R}$ is an interval, which extends the above result and correct the error in the proof of the inductive step mentioned above. As applications of the extension of the known result, four complete monotonicity propositions involving the Hurwitz zeta function, alternating Hurwitz zeta function, the confluent hypergeometric function of the second and Mills ratio are established, which yield corresponding Turán type inequalities for these special functions.
format Preprint
id arxiv_https___arxiv_org_abs_2507_10954
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Extension of a complete monotonicity theorem with applications
Yang, Zhen-Hang
Classical Analysis and ODEs
26A48, 44A10, 11M35, 33C15, 33B20, 26D15
Let $F_{p}(x) =L( t^{p}f(t)) =\int_{0}^{\infty }t^{p}f(t) e^{-xt}dt$ converge on $(0,\infty)$ for $p\in \mathbb{N}_{0}=\mathbb{N}\cup{0}$, where $f(t)$ is positive on $(0,\infty)$. In a recent paper [Z.-H. Yang, A complete monotonicity theorem related to Fink's inequality with applications, \emph{J. Math. Anal. Appl.} \textbf{551} (2025), no. 1, Paper no. 129600], the author proved the sufficient conditions for the function \begin{equation*} x\mapsto \prod_{j=1}^{n}F_{p_{j}}(x) -λ_{n}\prod_{j=1}^{n}F_{q_{j}}(x) \end{equation*} to be completely monotonic on $(0,\infty)$ by induction, where $\boldsymbol{p}_{[n] }=(p_{1},...,p_{n}) $ and $ \boldsymbol{q}_{[n] }=(q_{1},...,q_{n}) \in \mathbb{N }_{0}^{n}$ for $n\geq 2$ satisfy $\boldsymbol{p}_{[n] }\prec \boldsymbol{q}_{[n]}$ However, the proof of the inductive step is wrong. In this paper, we prove the above result also holds for $ \boldsymbol{p}_[n]},\boldsymbol{q}_{[n] }\in \mathbb{I}^{k}$, where $\mathbb{I}\subseteq \mathbb{R}$ is an interval, which extends the above result and correct the error in the proof of the inductive step mentioned above. As applications of the extension of the known result, four complete monotonicity propositions involving the Hurwitz zeta function, alternating Hurwitz zeta function, the confluent hypergeometric function of the second and Mills ratio are established, which yield corresponding Turán type inequalities for these special functions.
title Extension of a complete monotonicity theorem with applications
topic Classical Analysis and ODEs
26A48, 44A10, 11M35, 33C15, 33B20, 26D15
url https://arxiv.org/abs/2507.10954