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Motivated by existing results, we present some completely monotonic functions involving the polygamma functions.

Classical Analysis and ODEs · Mathematics 2010-12-03 Peng Gao

In the paper, we present a monotonicity result of a function involving the gamma function and the logarithmic function, refine a double inequality for the gamma function, and improve some known results for bounding the gamma function.

Classical Analysis and ODEs · Mathematics 2012-05-21 Feng Qi , Bai-Ni Guo

We present some completely monotonic functions involving the$q$-polygamma functions, our result generalizes some known results.

Classical Analysis and ODEs · Mathematics 2016-01-22 Peng Gao

In the paper, the authors introduce a matrix-parametrized generalization of the multinomial probability mass function that involves a ratio of several multivariate gamma functions. They show the logarithmic complete monotonicity of this…

Classical Analysis and ODEs · Mathematics 2022-07-29 Frédéric Ouimet , Feng Qi

We investigate conditions for logarithmic complete monotonicity of a quotient of two products of gamma functions, where the argument of each gamma function has different scaling factor. We give necessary and sufficient conditions in terms…

Classical Analysis and ODEs · Mathematics 2015-04-20 Dmitrii Karp , Elena Prilepkina

In the present paper, we establish necessary and sufficient conditions for the functions $x^\alpha\bigl\lvert\psi^{(i)}(x+\beta)\bigr\lvert$ and $\alpha\bigl\lvert\psi^{(i)}(x+\beta)\bigr\lvert-x\bigl\lvert\psi^{(i+1)}(x+\beta)\bigr\lvert$…

Classical Analysis and ODEs · Mathematics 2010-07-12 Feng Qi , Senlin Guo , Bai-Ni Guo

For $m,n\in \mathbb{N}$, let $0 < \alpha_i,\beta_j,\lambda_{ij} \leq 1$ be such that $\sum_{j=1}^n \lambda_{ij} = \alpha_i$, $\sum_{i=1}^m \lambda_{ij} = \beta_j$, and $\sum_{i=1}^m \alpha_i = \sum_{j=1}^n \beta_j \leq 1$. We prove that the…

Classical Analysis and ODEs · Mathematics 2019-11-07 Frédéric Ouimet

We prove some new results and unify the proofs of old ones involving complete monotonicity of expressions involving gamma and $q$-gamma functions, $0 < q < 1$. Each of these results implies the infinite divisibility of a related probability…

Classical Analysis and ODEs · Mathematics 2013-01-10 Mourad E. H. Ismail , Martin E. Muldoon

In this paper, we study completete monotonicity properties of the function $f_{a,k}(x)=\psi^{(k)}(x+a) - \psi^{(k)}(x) - \frac{ak!}{x^{k+1}}$, where $a\in(0,1)$ and $k\in \mathbb{N}_0$. Specifically, we consider the cases for $k\in \{ 2n:…

Classical Analysis and ODEs · Mathematics 2018-07-17 Kwara Nantomah

In the paper, the authors establish an inequality involving exponential functions and sums, introduce a ratio of many gamma functions, discuss properties, including monotonicity, logarithmic convexity, (logarithmically) complete…

Classical Analysis and ODEs · Mathematics 2021-01-05 Feng Qi , Wen-Hui Li , Shu-Bin Yu , Xin-Yu Du , Bai-Ni Guo

In this manuscript, we present the complete monotonicity of functions defined in terms of the poly-double gamma function \begin{align*} \psi_2^{(n)}(x) = (-1)^{n+1} n! \sum_{k=0}^{\infty} \dfrac{(1+k)}{(x+k)^{n+1}}, \quad x > 0, \ n\geq 2.…

General Mathematics · Mathematics 2025-11-12 Deepshikha Mishra , A. Swaminathan

In the paper, the authors review origins, motivations, and generalizations of a series of inequalities involving several exponential functions and sums, establish three new inequalities involving finite exponential functions and sums by…

Classical Analysis and ODEs · Mathematics 2020-08-26 Feng Qi , Bai-Ni Guo

Let $\psi(x)$ be the di-gamma function, the logarithmic derivative of the classical Euler's gamma function $\Gamma(x)$. In the paper, the author shows that the completely monotonic degree of the function $[\psi'(x)]^2+\psi''(x)$ is $4$,…

Classical Analysis and ODEs · Mathematics 2020-04-03 Feng Qi

In this note we prove a condition of monotonicity for the integral functional $ F(g) = \int_a^b h(x)\, d[-g(x)] $ with respect to $g$, a function of bounded variation. This condition is applied to analyze the behavior of a generalized…

Classical Analysis and ODEs · Mathematics 2015-03-19 Stefano Bertoni

We obtain necessary and sufficient conditions on a function in order that it be the Laplace transform of an absolutely monotonic function. Several closely related results are also given.

Classical Analysis and ODEs · Mathematics 2016-12-08 Stamatis Koumandos , Henrik L. Pedersen

In the paper, we establish an inequality involving the gamma and digamma functions and use it to prove the negativity and monotonicity of a function involving the gamma and digamma functions.

Classical Analysis and ODEs · Mathematics 2016-06-30 Feng Qi , Bai-Ni Guo

The aim of this paper is to develop analytic techniques to deal with certain monotonicity of combinatorial sequences. (1) A criterion for the monotonicity of the function $\sqrt[x]{f(x)}$ is given, which is a continuous analog for one…

Combinatorics · Mathematics 2015-04-29 Bao-Xuan Zhu

We introduce the notion of Dunkl completely monotonic functions on $\left(-\sigma,\sigma\right), \sigma>0$. We establish a restrictive version of the analogue of Schoenberg's theorem in Dunkl setting.

Classical Analysis and ODEs · Mathematics 2017-12-11 Jamel El Kamel , Khaled Mehrez

In the paper, we extend Binet's first formula for the logarithm of the gamma function and investigate some properties, including inequalities, star-shaped and sub-additive properties and the complete monotonicity, of the extended remainder…

Classical Analysis and ODEs · Mathematics 2010-07-14 Feng Qi , Bai-Ni Guo

We introduce completely monotonic functions of order $r>0$ and show that the remainders in asymptotic expansions of the logarithm of Barnes double gamma function and Euler's gamma function give rise to completely monotonic functions of any…

Classical Analysis and ODEs · Mathematics 2009-02-18 Stamatis Koumandos , Henrik L. Pedersen