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We develop a theory of universal central extensions of Hom-Lie algebras. Classical results of universal central extensions of Lie algebras cannot be completely extended to Hom-Lie algebras setting, because of the composition of two central…

Rings and Algebras · Mathematics 2012-09-27 J. M. Casas , M. A. Insua , N. Pacheco

We establish a Galois-theoretic interpretation of cohomology in semi-abelian categories: cohomology with trivial coefficients classifies central extensions, also in arbitrarily high degrees. This allows us to obtain a duality, in a certain…

Category Theory · Mathematics 2015-11-24 Diana Rodelo , Tim Van der Linden

We present a new approach to the amenability of groupoids (both in the measure theoretical and the topological setups) based on using Markov operators. We introduce the notion of an invariant Markov operator on a groupoid and show that the…

Functional Analysis · Mathematics 2007-05-23 Vadim A. Kaimanovich

Conformal dimension is a fundamental invariant of metric spaces, particularly suited to the study of self-similar spaces, such as spaces with an expanding self-covering (e.g. Julia sets of complex rational functions). The dynamics of these…

Group Theory · Mathematics 2025-08-06 Nicolás Matte Bon , Volodymyr Nekrashevych , Tianyi Zheng

In this paper we are concerned with the space of tempered ultrahyperfunctions corresponding to a proper open convex cone. A holomorphic extension theorem (the version of the celebrated edge of the wedge theorem) will be given for this…

Functional Analysis · Mathematics 2009-10-28 Daniel H. T. Franco

In this note we discuss how several results characterizing the qualitative behavior of solutions to the nonlinear Poisson equation can be generalized to harmonic maps with potential between complete Riemannian manifolds. This includes…

Differential Geometry · Mathematics 2017-08-04 Volker Branding

Let $L$ be a L\'evy operator. A function $h$ is said to be harmonic with respect to $L$ if $L h = 0$ in an appropriate sense. We prove Liouville's theorem for positive functions harmonic with respect to a general L\'evy operator $L$: such…

Analysis of PDEs · Mathematics 2024-11-28 Tomasz Grzywny , Mateusz Kwaśnicki

We study the equivalence between the $L^p$-parabolicity, the $L^q$-Liouville property of positive super-harmonic functions, and the existence of nonharmonic positive solutions to the following elliptic differential system \begin{equation*}…

Analysis of PDEs · Mathematics 2025-11-26 Lu Hao , Yuhua Sun

We derive some consequences of the Liouville theorem for plurisubharmonic functions of L.-F. Tam and the author. The first result provides a nonlinear version of the complex splitting theorem (which splits off a factor of $\mathbb{C}$…

Differential Geometry · Mathematics 2018-08-28 Lei Ni

This work consists in applying the analysis of integrable models to study the problem of Hyper-Kahler metrics building. In this context, we use the harmonic superspace language applied to D=2 N=4 SU(2) Liouville self interacting model and…

High Energy Physics - Theory · Physics 2007-05-23 M. Hssaini , M. Kessabi , B. Maroufi , M. B. Sedra

We study here the action of subgroups of PSL(2,R) on the space of harmonic functions on the unit disc bounded by a common constant, as well as the relationship this action has with the foliated Liouville problem: Given a foliation of a…

Dynamical Systems · Mathematics 2007-05-23 R. Feres , A. Zeghib

Transcendental Liouvillian extensions are differential fields, in which one can model poly-logarithmic, hyperexponential, and trigonometric functions, logarithmic integrals, and their (nested) rational expressions. For such an extension…

Symbolic Computation · Computer Science 2026-02-04 Shaoshi Chen , Hao Du , Yiman Gao , Hui huang , Wenqiao Li , Ziming Li

We introduce averaging operators on lattices $\mathbb{Z}^d$ and study the Liouville property for functions satisfying mean value properties associated to such operators. This framework encloses discrete harmonic, $p$-harmonic,…

Analysis of PDEs · Mathematics 2024-04-17 Tomasz Adamowicz , José G. Llorente

In this paper, we will use the normalized intetral Ricci curvature to investigate Liouville type property of $ p $ harmonic function on Riemannian manifold. secondly, we will use the BiRic curvature to obtian Liuville theorem for $ p $…

Differential Geometry · Mathematics 2022-10-26 Xiangzhi Cao

Let M be a projective manifold, p:M_{G} --> M a regular covering over M with a free abelian transformation group G. We describe holomorphic functions on M_{G} of an exponential growth with respect to the distance defined by a metric pulled…

Complex Variables · Mathematics 2007-05-23 Alexander Brudnyi

In this paper, we consider certain partially hyperbolic diffeomorphisms with center of arbitrary dimension and obtain continuity properties of the topological entropy under $C^1$ perturbations. The systems considered have subexponential…

Dynamical Systems · Mathematics 2022-06-22 Weisheng Wu

In this paper, we consider $\alpha$-harmonic functions in the half space $\mathbb{R}^n_+$: \begin{equation} \left\{\begin{array}{ll} (-\Delta)^{\alpha/2} u(x)=0,~u(x)>0, & x\in\mathbb{R}^n_+, \\ u(x)\equiv 0, & x\notin \mathbb{R}^{n}_{+}.…

Analysis of PDEs · Mathematics 2014-09-16 Wenxiong Chen , Congming Li , Lizhi Zhang , Tingzhi Cheng

A Liouville function is a complex analytic function H with a Taylor series \sum_{n=1}^{\infty} x^n/a_n such the a_n's form a ``very fast growing'' sequence of integers. In this paper we exhibit the complete first-order theory of the complex…

Logic · Mathematics 2007-05-23 Pascal Koiran

Let G be a group which is topologically a CW-complex, BG a classifying space for G, and A a discrete abelian group. To a central extension of G by A, one can associate a cohomology class in $H^2(BG,A)$. We show this association is…

Algebraic Topology · Mathematics 2024-03-05 Rohit Joshi , Steven Spallone

The behavior of factorization properties in various ring extensions is a central theme in commutative algebra. Classically, the UFDs are (completely) integrally closed and tend to behave well in standard ring extensions, with the notable…

Commutative Algebra · Mathematics 2025-04-16 Jason Boynton , Jim Coykendall , Grant Moles , Chelsey Morrow