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We introduce almost periodic Banach--Malcev algebras as a non-associative extension of Bohr's classical theory. Our framework is based on the relative compactness of adjoint orbits $\{e^{t\,\mathrm{ad}(x)}(y)\}$, which yields the spectral…

Differential Geometry · Mathematics 2025-12-16 Marwa Ennaceur

We derive sharp estimates on the modulus of continuity for solutions of a large class of quasilinear isotropic parabolic equations on smooth metric measure spaces (with Dirichlet or Neumann boundary condition in case the boundary is…

Differential Geometry · Mathematics 2020-09-23 Xiaolong Li , Yucheng Tu , Kui Wang

We characterize the relatively compact subsets of $L^1\left(\| m \| \right),$ the quasi-Banach function space associated to the semivariation of a given vector measure $m$ showing that the strong connection between compactness, uniform…

Functional Analysis · Mathematics 2019-10-30 Ricardo del Campo , Antonio Fernández , Fernando Mayoral , Francisco Naranjo

Fenchel subdifferential operators of lower semicontinuous proper convex functions on real Banach spaces are classically characterized as those operators that are maximally cyclically monotone or, equivalently, maximally monotone and…

Functional Analysis · Mathematics 2022-12-16 Juan Enrique Martínez-Legaz

We extend the methods used by V. Ferenczi and Ch. Rosendal to obtain the `third dichotomy' in the program of classification of Banach spaces up to subspaces, in order to prove that a Banach space E with an admissible system of blocks with…

Functional Analysis · Mathematics 2023-12-04 Alejandra C. Cáceres-Rigo , Valentin Ferenczi

We study quasi-modular pseudometric spaces as asymmetric refinements of modular metric structures. To each such space we associate canonical forward and backward quasi-uniformities and the corresponding directional topologies. We introduce…

General Topology · Mathematics 2026-02-03 Philani Rodney Majozi

In this article, we introduce and investigate the concept of partial quasi-metric type space as a generalization of both partial quasi-metric and quasi-metric type spaces. We show that many important constructions studied in K\"unzi's…

General Topology · Mathematics 2019-03-18 Yaé Ulrich Gaba

Let G be a Lie group and g its Lie algebra. We develop a theory of quasi Poisson structures relative to a not necessarily non-degenerate Ad-invariant symmetric 2-tensor in the tensor square of g and one of general not necessarily…

Differential Geometry · Mathematics 2026-01-22 Johannes Huebschmann

In any semigroup $S$ satisfying the Strong Folner Condition, there are three natural notions of density for a subset $A$ of $S$: Folner density $d(A)$, Banach density $d^*(A)$, and translation density $d_t(A)$. If $S$ is commutative or left…

Combinatorics · Mathematics 2025-07-23 Daniel Glasscock , Neil Hindman , Dona Strauss

In this paper, we prove the following version of the famous Bernstein's theorem: Let $X\subset \mathbb R^{n+k}$ be a closed and connected set with Hausdorff dimension $n$. Assume that $X$ satisfies the monotonicity formula at $p\in X$.…

Differential Geometry · Mathematics 2024-04-10 José Edson Sampaio , Euripedes Carvalho da Silva

We show that a group admits a non-zero homogeneous quasimorphism if and only if it admits a certain type of action on a poset. Our proof is based on a construction of quasimorphisms which generalizes Poincar\'e--Ghys' construction of the…

Group Theory · Mathematics 2011-07-12 Gabi Ben Simon , Tobias Hartnick

We investigate spaceability phenomena in linear dynamics from a structural perspective. Given a continuous linear operator \(T:X \to X\), we introduce the set \(\Omega(T)\), consisting of all continuous linear operators \(h:X \to X\) for…

Functional Analysis · Mathematics 2025-09-09 Manuel Saavedra , Manuel Stadlbauer

Naor and Mendel's metric cotype extends the notion of the Rademacher cotype of a Banach space to all metric spaces. Every Banach space has metric cotype at least 2. We show that any metric space that is bi-Lipschitz equivalent to an…

Metric Geometry · Mathematics 2010-09-20 Ellen Veomett , Kevin Wildrick

In this note, we study some concentration properties for Lipschitz maps defined on Hamming graphs, as well as their stability under sums of Banach spaces. As an application, we extend a result of Causey on the coarse Lipschitz structure of…

Functional Analysis · Mathematics 2023-01-27 Audrey Fovelle

We review the theory of Va\u{i}nberg--Br\`{e}gman relative entropies and quasinonexpansive operators on reflexive Banach spaces, and obtain several new results. We also develop an extension of this theory to nonreflexive Banach spaces,…

Functional Analysis · Mathematics 2026-02-17 Ryshard-Pavel Kostecki

In their seminal work J. Lepowsky and R. L. Wilson gave a vertex-operator theoretic interpretation of Gordon-Andrews-Bressoud's generalization of Rogers-Ramanujan combinatorial identities, by constructing bases of vacuum spaces for the…

Quantum Algebra · Mathematics 2018-07-31 Slaven Kozic , Mirko Primc

An algebra A of operators on a Banach space X is called strictly semi-transitive if for all non-zero x,y in X there exists an operator S in A such that Sx=y or Sy=x. We show that if A is norm-closed and strictly semi-transitive, then every…

Functional Analysis · Mathematics 2007-05-23 H. P. Rosenthal , V. G. Troitsky

We construct various examples of Sobolev-type functions, defined via upper gradients in metric spaces, that fail to be quasicontinuous or weakly quasicontinuous. This is done with quasi-Banach function lattices $X$ as the function spaces…

Functional Analysis · Mathematics 2025-03-28 Anders Björn , Jana Björn , Lukáš Malý

Let $X$ be a separable nonquasireflexive Banach space. Let $Y$ be a Banach space isomorphic to a subspace of $X^*$. The paper is devoted to the following questions: 1. Under what conditions does there exist an isomorphic embedding $T:Y\to…

Functional Analysis · Mathematics 2010-09-07 Mikhail I. Ostrovskii

In this paper we completely characterize the norm attainment set of a bounded linear operator on a Hilbert space. This partially answers a question raised recently in [\textit{D. Sain, On the norm attainment set of a bounded linear…

Functional Analysis · Mathematics 2019-03-20 Debmalya Sain