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This paper studies the class of logarithmically completely monotonic (LCM) functions. These functions play an important role in characterising externally positive linear systems which find applications in important control problems such as…

Optimization and Control · Mathematics 2025-07-08 Hamed Taghavian , Ross Drummond , Mikael Johansson

In the paper, necessary and sufficient conditions are presented for a function involving a ratio of gamma functions to be logarithmically completely monotonic. This extends and generalizes the main result in [\emph{Inequalities and…

Classical Analysis and ODEs · Mathematics 2012-08-21 Feng Qi , Bai-Ni Guo

We investigate conditions for logarithmic complete monotonicity of product ratios of gamma and q-gamma functions whose arguments are linear functions of the variable. We give necessary and sufficient conditions in terms of nonnegativity of…

Classical Analysis and ODEs · Mathematics 2020-04-30 Christian Berg , Asena Cetinkaya , Dmitrii Karp

The necessary and sufficient conditions for differentiability of a function of several real variables stated and proved and its ramifications discussed.

Classical Analysis and ODEs · Mathematics 2007-05-23 R. P. Venkataraman

It is proved that harmonic functions are characterized by harmonicity of their spherical means, for which purpose the iterated spherical means are used. The similar characterization of solutions to the modified Helmholtz equation…

Analysis of PDEs · Mathematics 2021-10-12 Nikolay Kuznetsov

In the article, a notion "logarithmically absolutely monotonic function" is introduced, an inclusion that a logarithmically absolutely monotonic function is also absolutely monotonic is revealed, the logarithmically complete monotonicity…

Classical Analysis and ODEs · Mathematics 2010-08-20 Feng Qi , Bai-Ni Guo

We introduce the notion of characteristic function of a quaternionic matrix, whose roots are the left eigenvalues. We prove that for all $2\times 2$ matrices and for $3\times 3$ matrices having some zero entry outside the diagonal there is…

Rings and Algebras · Mathematics 2010-05-11 E. Macías-Virgós , M. J. Pereira-Sáez

This paper concerns generalized differential characterizations of maximal monotone set-valued mappings. Using advanced tools of variational analysis, we establish coderivative criteria for maximal monotonicity of set-valued mappings, which…

Optimization and Control · Mathematics 2015-01-05 N. H. Chieu , G. M. Lee , B. S. Mordukhovich , T. T. A. Nghia

This paper gives a definition of g-harmonic functions and shows the relation between the g-harmonic functions and g-martingales. It's direct to construct such relation under smooth case, but for continuous case we need the theory of…

Probability · Mathematics 2011-10-11 Liang Cai

When dealing with certain mathematical problems, it is sometimes necessary to show that some function induces a metric on a certain space. When this function is not a well renowned example of a distance, one has to develop very particular…

General Mathematics · Mathematics 2023-05-23 Daniel Cao Labora , Francisco Javier Fernández , Fernando Adrián F. Tojo , Carlos Villanueva

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

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

Results involving various mean value properties are reviewed for harmonic, biharmonic and metaharmonic functions. It is also considered how the standard mean value property can be weakened to imply harmonicity and belonging to other classes…

Analysis of PDEs · Mathematics 2019-05-23 Nikolay Kuznetsov

A function on a (generally infinite) graph $\G$ with values in a field $K$ of characteristic 2 will be called {\it harmonic} if its value at every vertex of $\G$ is the sum of its values over all adjacent vertices. We consider binary…

Mathematical Physics · Physics 2007-05-23 Mikhail Zaidenberg

For normalized harmonic functions $f(z)=h(z)+\bar{g(z)}$ in the open unit disk $\mathbb{U}$, a sufficient condition on $h(z)$ for $f(z)$ to be $p$-valent in $\mathbb{U}$ is discussed. Moreover, some interesting examples and images of $f(z)$…

Complex Variables · Mathematics 2013-09-19 Toshio Hayami

In this work we establish a connection between two classical notions, unrelated so far: Harmonic functions on the one hand and absolutely monotonic functions on the other hand. We use this to prove convexity type and propagation of…

Analysis of PDEs · Mathematics 2015-12-09 Gabor Lippner , Dan Mangoubi

Absolute continuity implies uniform continuity, but generally not vice versa. In this short note, we present one sufficient condition for a uniformly continuous function to be absolutely continuous, which is the following theorem: For a…

Classical Analysis and ODEs · Mathematics 2015-03-17 Kai Yang , Chenhong Zhu

A probability measure is a characteristic measure of a topological dynamical system if it is invariant to the automorphism group of the system. We show that zero entropy shifts always admit characteristic measures. We use similar techniques…

Dynamical Systems · Mathematics 2021-07-01 Joshua Frisch , Omer Tamuz

An intuitive probabilistic alternative for the construction of the Martin boundary is presented along with a construction of maximal representing measures for positive harmonic functions.

Analysis of PDEs · Mathematics 2019-11-13 Peter A. Loeb

We classify all functions which, when applied term by term, leave invariant the sequences of moments of positive measures on the real line. Rather unexpectedly, these functions are built of absolutely monotonic components, or reflections of…

Classical Analysis and ODEs · Mathematics 2022-05-17 Alexander Belton , Dominique Guillot , Apoorva Khare , Mihai Putinar

We give a criterium of holomorphy for some type formal power series. This gives a stronger form of a Rothstein's type extension theorem for a particular ring of holomorphic functions.

Dynamical Systems · Mathematics 2007-05-23 Ricardo Perez-Marco