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In this paper we prove a general convergence theorem for almost-additive set functions on unimodular, amenable groups. These mappings take their values in some Banach space. By extending the theory of epsilon-quasi tiling techniques, we set…

Dynamical Systems · Mathematics 2017-10-26 Felix Pogorzelski

We obtain a complete characterization of the bounded Hausdorff operators acting on a Fock space $F^p_\alpha$ and taking its values into a larger one $F^q_\alpha,\ 0 < p \leq q \leq \infty,$ as well as some necessary or sufficient conditions…

Functional Analysis · Mathematics 2023-10-05 Óscar Blasco , Antonio Galbis

We review various characterizations of uniform convexity and smoothness on norm balls in finite-dimensional spaces and connect results stemming from the geometry of Banach spaces with \textit{scaling inequalities} used in analysing the…

Optimization and Control · Mathematics 2021-02-19 Thomas Kerdreux , Alexandre d'Aspremont , Sebastian Pokutta

There are two main aims of the paper. The first one is to extend the criterion for the precompactness of sets in Banach function spaces to the setting of quasi-Banach function spaces. The second one is to extend the criterion for the…

Functional Analysis · Mathematics 2017-01-11 António Caetano , Amiran Gogatishvili , Bohumír Opic

We first give simplified and corrected accounts of some results in \cite{PiRCP} on compactifications of pseudofinite groups. For instance, we use a classical theorem of Turing \cite{Turing} to give a simplified proof that any definable…

Logic · Mathematics 2025-06-18 Gabriel Conant , Ehud Hrushovski , Anand Pillay

Commutators of a large class of bilinear operators and multiplication by functions in a certain subspace of the space of functions of bounded mean oscillations are shown to be jointly compact. Under a similar commutation, fractional…

Classical Analysis and ODEs · Mathematics 2013-10-16 Árpád Bényi , Wendolín Damián , Kabe Moen , Rodolfo H. Torres

Let $G$ be a locally compact group, and take $p\in(1,\infty)$. We prove that the Banach left $L^1(G)$-module $L^p(G)$ is injective (if and) only if the group $G$ is amenable. Our proof uses the notion of multi-norms. We also develop the…

Functional Analysis · Mathematics 2012-02-28 H. Garth Dales , Matthew Daws , Hung Le Pham , Paul Ramsden

Let $G$ be a locally compact group and $1\leq p<\infty$. Based on some important earlier works, in this paper the concept of $L_p^T-$function is introduced. Then the structure of the space $L^{T}_p(G)$, which is consisting of all…

Functional Analysis · Mathematics 2021-10-14 F. Abtahi H. G. Amini , A. Rejali

We further investigate the weak topology generated by the irreducible unitary representations of a group $G$. A deep result due to Ernest \cite{Ernest1971} and Hughes \cite{Hughes1973} asserts that every weakly compact subset of a locally…

General Topology · Mathematics 2021-03-25 María V. Ferrer , Salvador Hernández

The class of locally compact near abelian groups is introduced and investigated as a class of metabelian groups formalizing and applying the concept of scalar multiplication. The structure of locally compact near abelian groups and its…

Group Theory · Mathematics 2017-02-14 Karl H. Hofmann , Wolfgang Herfort , Francesco G. Russo

We investigate various relaxations of additivity for set maps into Banach spaces in the context of representations of amenable groups. Specifically, we establish conditions under which asymptotically additive and almost additive set maps…

Dynamical Systems · Mathematics 2025-01-27 Raimundo Briceño , Godofredo Iommi

Answering in the affirmative a question posed in [Y.A.Abramovich, C.D.Aliprantis and O.Burkinshaw, Multiplication and compact-friendly operators, Positivity 1 (1997), 171--180], we prove that a positive multiplication operator on any…

Functional Analysis · Mathematics 2007-05-23 Y. A. Abramovich , C. D. Aliprantis , O. Burkinshaw , A. W. Wickstead

We provide a new characterization of amenability for countable groups, based on frame representations admitting almost invariant vectors. By relaxing the frame inequalities, thereby weakening amenability, we obtain a large class of…

Group Theory · Mathematics 2025-12-03 Dorin Ervin Dutkay , Catalin Georgescu , Gabriel Picioroaga

We prove several theorems relating amenability of groups in various categories (discrete, definable, topological, automorphism group) to model-theoretic invariants (quotients by connected components, Lascar Galois group, G-compactness,…

Logic · Mathematics 2019-01-11 Krzysztof Krupinski , Anand Pillay

We investigate weak amenability of the Banach algebra A(X) of approximable operators on a Banach space X and its relation to factorization properties of operators in A(X). We show that if A(X) is weakly amenable, then either A(X) is…

Functional Analysis · Mathematics 2007-05-23 Niels Grønbæk

We characrterize extreme contractions defined between \ finite-dimensional polyhedral Banach spaces using $k$- smoothness of operators. We also explore weak L-P property, a recently introduced concept in the study of extreme contractions.…

Functional Analysis · Mathematics 2024-08-14 Arpita Mal , Kallol Paul , Subhrajit Dey

For a locally convex $^*$-algebra $A$ equipped with a fixed continuous $^*$-character $\varepsilon$, we define a cohomological property, called property $(FH)$, which is similar to character amenability. Let $C_c(G)$ be the space of…

Functional Analysis · Mathematics 2015-09-08 Xiao Chen , Anthony To-Ming Lau , Chi-Keung Ng

We prove a characterization of the amenability of countable Borel equivalence relations in terms of the uniform Liouville property for group actions on their classes. Furthermore, inspired by a well-known amenability criterion for locally…

Group Theory · Mathematics 2026-03-10 Maksym Chaudkhari , Kate Juschenko , Friedrich Martin Schneider

We introduce new class of limitedly L-weakly compact operators from a Banach space to a Banach lattice. This class is a proper subclass of the Bourgain-Diestel operators and it contains properly the class of L-weakly compact operators. We…

Functional Analysis · Mathematics 2023-06-29 Safak Alpay , Svetlana Gorokhova , Eduard Emelyanov

In his study of amenable unitary representations, M. E. B. Bekka asked if there is an analogue for such representations of the remarkable fixed-point property for amenable groups. In this paper, we prove such a fixed-point theorem in the…

Operator Algebras · Mathematics 2007-05-23 Anthony T. Lau , Alan L. T. Paterson