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We characterise slice-regularity of functions over a real alternative *-algebra using operators that arise in Dunkl operator theory. We present a unifying perspective on hypercomplex analysis by defining a family of function spaces in the…

Complex Variables · Mathematics 2026-02-03 Giulio Binosi , Alessandro Perotti

A countable group $G$ has the strong topological Rokhlin property (STRP) if it admits a continuous action on the Cantor space with a comeager conjugacy class. We show that having the STRP is a symbolic dynamical property. We prove that a…

Dynamical Systems · Mathematics 2024-03-11 Michal Doucha

We characterize the simplicity of Pimsner algebras for non-proper C*-correspondences. With the aid of this criterion, we give a systematic strategy to produce outer actions of unitary tensor categories on Kirchberg algebras. In particular,…

Operator Algebras · Mathematics 2025-09-15 Kan Kitamura

Continuous actions of topological groups on compact Hausdorff spaces $X$ are investigated which induce almost periodic functions in the corresponding commutative C*-algebra. The unique invariant mean on the group resulting from averaging…

Operator Algebras · Mathematics 2009-03-11 M. Frank , V. Manuilov , E. Troitsky

Let $\Gamma$ be a discrete group. To every ideal in $\ell^{\infty}(\G)$ we associate a C$^*$-algebra completion of the group ring that encapsulates the unitary representations with matrix coefficients belonging to the ideal. The general…

Operator Algebras · Mathematics 2014-02-26 Nathanial P. Brown , Erik Guentner

We construct the first example of a $C^*$-algebra $A$ with the properties in the title. This gives a new example of non-nuclear $A$ for which there is a unique $C^*$-norm on $A \otimes A^{op}$. This example is of particular interest in…

Operator Algebras · Mathematics 2023-04-05 Gilles Pisier

We report on some computational experiments related to the trivial units property and unique product property for group rings of torsion-free groups. These properties are related to Kaplansky's unit and zero-divisor conjectures. Our…

Group Theory · Mathematics 2026-03-26 Heiko Dietrich , Melissa Lee , Andre Nies , Marc Vinyals

We say that an inclusion of an algebra $A$ into a $C^*$-algebra $B$ has the ideal separation property if closed ideals in $B$ can be recovered by their intersection with $A$. Such inclusions have attractive properties from the point of view…

Operator Algebras · Mathematics 2025-03-05 Are Austad , Hannes Thiel

We analyze the singularities of rational inner functions on the unit bidisk and study both when these functions belong to Dirichlet-type spaces and when their partial derivatives belong to Hardy spaces. We characterize derivative…

Complex Variables · Mathematics 2018-02-13 Kelly Bickel , James Eldred Pascoe , Alan Sola

We prove that an inclusion $\mathcal{B} \subset \mathcal{A}$ of simple unital $C^*$-algebras with a finite-index conditional expectation is regular if and only if there exists a finite group $G$ that admits a cocycle action…

Operator Algebras · Mathematics 2026-01-01 Keshab Chandra Bakshi , Ved Prakash Gupta

We introduce the tracial quasi-Rokhlin property for an automorphism alpha of a unital C*-algebra A, which is not assumed to be simple. We show that under suitable hypotheses, the associated crossed product C*-algebra C*(Z,A,alpha) is…

Operator Algebras · Mathematics 2013-07-01 Julian Buck

Using duality and topological theory of well behaved Hopf algebras (as defined in [2]) we construct star-product models of non compact quantum groups from Drinfeld and Reshetikhin standard deformations of enveloping Hopf algebras of simple…

High Energy Physics - Theory · Physics 2009-10-28 Frédéric Bidegain , Georges Pinczon

We investigate topologies on groups which arise naturally from their algebraic structure, including the Frech\'et-Markov, Hausdorff-Markov, and various kinds of Zariski topologies. Answering a question by Dikranjan and Toller, we show that…

Group Theory · Mathematics 2025-06-24 S. Bardyla , L. Elliott , J. D. Mitchell , Y. Péresse

We obtain several fundamental results on finite index ideals and additive subgroups of rings as well as on model-theoretic connected components of rings, which concern generating in finitely many steps inside additive groups of rings. Let…

Logic · Mathematics 2025-12-04 Krzysztof Krupiński , Tomasz Rzepecki

We show that cluster algebras do not contain non-trivial units and that all cluster variables are irreducible elements. Both statements follow from Fomin and Zelevinsky's Laurent phenomenon. As an application we give a criterion for a…

Rings and Algebras · Mathematics 2013-05-10 Christof Geiß , Bernard Leclerc , Jan Schröer

Let $p\in(1,\infty)$. We show that there is an isomorphism from any separable unital subalgebra of $B(\ell^{2})/K(\ell^{2})$ onto a subalgebra of $B(\ell^{p})/K(\ell^{p})$ that preserves the Fredholm index. As a consequence, every separable…

Operator Algebras · Mathematics 2024-09-12 March T. Boedihardjo

We associate with the ring $R$ of algebraic integers in a number field a C*-algebra $\cT[R]$. It is an extension of the ring C*-algebra $\cA[R]$ studied previously by the first named author in collaboration with X.Li. In contrast to…

Operator Algebras · Mathematics 2012-06-12 Joachim Cuntz , Christopher Deninger , Marcelo Laca

We prove that separable, simple, unital, non-elementary, stably finite C*-algebras that have stable rank one, and that have locally finite nuclear dimension in a tracial sense, have uniform property $\Gamma$. In particular, Villadsen…

Operator Algebras · Mathematics 2026-05-05 Andrea Vaccaro

The note is concerned with inductive systems of Toeplitz algebras and their $*$-homomorphisms over arbitrary partially ordered sets. The Toeplitz algebra is the reduced semigroup $C^*$-algebra for the additive semigroup of non-negative…

Operator Algebras · Mathematics 2019-05-17 E. V. Lipacheva

A functor from the category of directed trees with inclusions to the category of commutative C*-algebras with injective *-homomorphisms is constructed. This is used to define a functor from the category of directed graphs with inclusions to…

Operator Algebras · Mathematics 2007-05-23 Jack Spielberg