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Given a discrete measured groupoid $\mathcal{G}$, we study properties of the corresponding von Neumann algebra $L(\mathcal{G})$ using the techniques of Popa's deformation/rigidity theory. More specifically, we define and study the Gaussian…

Operator Algebras · Mathematics 2025-09-19 Felipe Flores , James Harbour

We introduce abelian framed bicategories, which are particular framed bicategories that are locally abelian, and show that they are suitable for developing homology and cohomology theories for directed structures. This means in particular…

Category Theory · Mathematics 2026-02-05 Augustin Albert , Jérémy Dubut , Eric Goubault

In this paper, the notion of proper proximality (introduced in [BIP18]) is studied and classified in various families of groups. We show that if a group acts non-elementarily by isometries on a tree such that for any two edges, the…

Group Theory · Mathematics 2022-02-17 Changying Ding , Srivatsav Kunnawalkam Elayavalli

In this paper we present parallel theories on constructing Wiener algebras in the bicomplex setting. With the appropriate symmetry condition, the bicomplex matrix valued case can be seen as a complex valued case and, in this matrix valued…

Complex Variables · Mathematics 2022-06-28 Daniel Alpay , Izchak Lewkowicz , Mihaela Vajiac

Condensed mathematics, developed by Clausen and Scholze over the last few years, is a new way of studying the interplay between algebra and geometry. It replaces the concept of a topological space by a more sophisticated but better-behaved…

Logic · Mathematics 2024-10-24 Dagur Asgeirsson

We extend Ueda's peak set theorem for subdiagonal subalgebras of tracial finite von Neumann algebras, to sigma-finite von Neumann algebras (that is, von Neumann algebras with a faithful state; which includes those on a separable Hilbert…

Operator Algebras · Mathematics 2018-08-09 David P. Blecher , Louis Labuschagne

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

There is a well developed theory of weakly symmetric Riemannian manifolds. Here it is shown that several results in the Riemannian case are also valid for weakly symmetric pseudo-Riemannian manifolds, but some require additional hypotheses.…

Differential Geometry · Mathematics 2011-07-26 Zhiqi Chen , Joseph A. Wolf

This book introduces the concept of neutrosophic bilinear algebras and their generalizations to n-linear algebras, n>2. This book has five chapters. The first chapter is introductory in nature and gives a few essential definitions and…

General Mathematics · Mathematics 2010-07-02 W. B. Vasantha Kandasamy , Florentin Smarandache

In this paper, we introduce the concept of a "von Neumann regular $\mathcal{C}^{\infty}$-ring", which is a model for a specific equational theory. We delve into the characteristics of these rings and demonstrate that each Boolean space can…

Rings and Algebras · Mathematics 2024-04-15 Jean Cerqueira Berni , Hugo Luiz Mariano

Quantum bialgebras derivable from Uq(sl2) which contain idempotents and von Neumann regular Cartan-like generators are introduced and investigated. Various types of antipodes (invertible and von Neumann regular) on these bialgebras are…

Quantum Algebra · Mathematics 2014-11-18 Steven Duplij , Sergey Sinel'shchikov

Division algebras have demonstrated their utility in studying non-associative algebras and their connection to the Standard Model through complex Clifford algebras. This article focuses on exploring the connection between these complex…

High Energy Physics - Theory · Physics 2023-12-19 Armando Reynoso

The aim of the article is to provide characterizations of the Haage-rup property for locally compact, second countable groups in terms of approximations of some non-ergodic invariant states by mixing ones for actions on unital…

Group Theory · Mathematics 2025-08-05 Paul Jolissaint

Mimicking the von Neumann version of Kustermans and Vaes' locally compact quantum groups, Franck Lesieur had introduced a notion of measured quantum groupoid, in the setting of von Neumann algebras. In a former article, the author had…

Operator Algebras · Mathematics 2010-02-24 Michel Enock

This book is organized into seven chapters. Chapter one is introductory in content. The notion of neutrosophic set linear algebras and neutrosophic neutrosophic set linear algebras are introduced and their properties analysed in chapter…

General Mathematics · Mathematics 2010-03-10 W. B. Vasantha Kandasamy , Florentin Smarandache , K. Ilanthenral

We initiate a study of maximal subgroups and maximal von Neumann subalgebras which have the Haagerup property. We determine maximal Haagerup subgroups inside $\mathbb{Z}^2 \rtimes SL_2(\mathbb{Z})$ and obtain several explicit instances…

Operator Algebras · Mathematics 2021-08-11 Yongle Jiang , Adam Skalski

In this paper, we define and study a particular case of von Neumann regular notion called a weak von Neumann regular ring. It shown that the polynomial ring $R[x]$ is weak von Neumann regular if and only if $R$ has exactly two idempotent…

Commutative Algebra · Mathematics 2010-02-03 Mohammed Kabbour , Najib Mahdou

We use deformation-rigidity theory in von Neumann algebra framework to study probability measure preserving actions by wreath product groups. In particular, we single out large families of wreath products groups satisfying various type of…

Operator Algebras · Mathematics 2018-02-27 Ionut Chifan , Sorin Popa , James Owen Sizemore

In this note, we will point out, as a corollary of Popa's rigidity theory, that the crossed product von Neumann algebras for Bernoulli shifts cannot have relative property T. This is an operator algebra analogue of the theorem shown by…

Operator Algebras · Mathematics 2007-05-23 Tomohiro Hayashi

We introduce a natural pseudometric on the space of actions of d-generated groups. In this pseudometric, the zero classes correspond to the weak equivalence classes defined by Kechris, and the metric identification is compact. We achieve…

Functional Analysis · Mathematics 2025-03-18 Miklos Abert , Gabor Elek