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In this paper, we initiate the study of higher rank Baumslag-Solitar semigroups and their related C*-algebras. We focus on two extreme, but interesting, classes - one is related to products of odometers and the other is related to…

Operator Algebras · Mathematics 2025-04-25 Robert Valente , Dilian Yang

There are many deep results on the structure of REGULAR probability measures $P(G)$ on compact/locally compact, Hausdorff topological groups G. See, for instance, the classic monographs by KR Parthasarathy, Ulf Grenander, A.Mukherjea and…

Functional Analysis · Mathematics 2022-05-24 M. N. N. Namboodiri

We study the discrete quantum groups $\Gamma$ whose group algebra has an inner faithful representation of type $\pi:C^*(\Gamma)\to M_K(\mathbb C)$. Such a representation can be thought of as coming from an embedding $\Gamma\subset U_K$. Our…

Operator Algebras · Mathematics 2015-12-14 Teodor Banica , Julien Bichon

Suzuki recently gave constructions of non-discrete examples of locally compact C*-simple groups and Raum showed C*-simplicity of the relative profinite completions of the Baumslag-Solitar groups by using Suzuki's results. We extend this…

Operator Algebras · Mathematics 2022-01-28 Miho Mukohara

We study two classes of operator algebras associated with a unital subsemigroup $P$ of a discrete group $G$: one related to universal structures, and one related to co-universal structures. First we provide connections between universal…

Operator Algebras · Mathematics 2022-03-09 Evgenios T. A. Kakariadis , Elias G. Katsoulis , Marcelo Laca , Xin Li

In this paper we associate to every reduced C*-algebraic quantum group A a universal C*-algebraic quantum group. We fine tune a proof of Kirchberg to show that every *-representation of a modified L1-space is generated by a unitary…

Operator Algebras · Mathematics 2007-05-23 Johan Kustermans

We compute the $ K $-theory of quantum automorphism groups of finite dimensional $ C^* $-algebras in the sense of Wang. The results show in particular that the $ C^* $-algebras of functions on the quantum permutation groups $ S_n^+ $ are…

Operator Algebras · Mathematics 2015-09-03 Christian Voigt

We analyze the recent examples of quantum semigroups defined by M.M. Sadr who also brought up several open problems concerning these objects. These are defined as quantum families of maps from finite sets to a fixed compact quantum…

Operator Algebras · Mathematics 2014-10-30 Piotr M. Soltan

The aim of the present paper is to define and study a new class of groups, namely Wm-groups with a single binary operation based on axioms of semi commutativity, right identity and left inverse. Moreover, we introduce the notions of right…

General Mathematics · Mathematics 2019-11-12 Hariwan Z. Ibrahim , Muwafaq M. Salih

The most developed aspect of the theory of finite semigroups is their classification in pseudovarieties. The main motivation for investigating such entities comes from their connection with the classification of regular languages via…

Group Theory · Mathematics 2025-04-14 Jorge Almeida

We generalize the notion of weakly mixing unitary representations to locally compact quantum groups, introducing suitable extensions of all standard characterizations of weak mixing to this setting. These results are used to complement the…

Operator Algebras · Mathematics 2017-07-11 Ami Viselter

The quasiprobability representation of quantum states addresses two main concerns, the identification of nonclassical features and the decomposition of the density operator. While the former aspect is a main focus of current research, the…

Quantum Physics · Physics 2018-10-26 J. Sperling , I. A. Walmsley

A function on a discrete group is weakly combable if its discrete derivative with respect to a combing can be calculated by a finite state automaton. A weakly combable function is bicombable if it is Lipschitz in both the left and right…

Group Theory · Mathematics 2010-09-14 Danny Calegari , Koji Fujiwara

Quantum families of maps between quantum spaces are defined and studied. We prove that quantum semigroup (and sometimes quantum group) structures arise naturally on such objects out of more fundamental properties. As particular cases we…

Operator Algebras · Mathematics 2015-06-26 Piotr M. Soltan

Positive $C_0$-semigroups that occur in concrete applications are, more often than not, irreducible. Therefore a deep and extensive theory of irreducibility has been developed that includes characterizations, perturbation analysis, and…

Functional Analysis · Mathematics 2024-06-28 Sahiba Arora , Jochen Glück

This (quasi-)survey addresses the quasi-isometry classification of locally compact groups, with an emphasis on amenable hyperbolic locally compact groups. This encompasses the problem of quasi-isometry classification of homogeneous…

Group Theory · Mathematics 2020-05-05 Yves Cornulier

We consider locally equi-continuous strongly continuous semigroups on locally convex spaces (X,tau). First, we show that if (X,tau) has the property that weak* compact sets of the dual are equi-continuous, then strong continuity of the…

Functional Analysis · Mathematics 2019-09-13 Richard C. Kraaij

Strongly continuous semigroups of unital completely positive maps (i.e. quantum Markov semigroups or quantum dynamical semigroups) on compact quantum groups are studied. We show that quantum Markov semigroups on the universal or reduced…

Operator Algebras · Mathematics 2014-02-18 Fabio Cipriani , Uwe Franz , Anna Kula

In this article we initiate research on locally compact C*-simple groups. We first show that every C*-simple group must be totally disconnected. Then we study C*-algebras and von Neumann algebras associated with certain groups acting on…

Operator Algebras · Mathematics 2016-01-25 Sven Raum

We describe the $C^*$-algebra of an $E$-unitary or strongly 0-$E$-unitary inverse semigroup as the partial crossed product of a commutative $C^*$-algebra by the maximal group image of the inverse semigroup. We give a similar result for the…

Operator Algebras · Mathematics 2015-12-08 David Milan , Benjamin Steinberg