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It is shown that every Jiang-Su stable approximately subhomogeneous C*-algebra has finite decomposition rank. Previously, it was not even known that such algebras have finite nuclear dimension. A key step in the proof is that subhomogeneous…

Operator Algebras · Mathematics 2020-03-12 George A. Elliott , Zhuang Niu , Luis Santiago , Aaron Tikuisis

We compute the nuclear dimension of separable, simple, unital, nuclear, Z-stable C*-algebras. This makes classification accessible from Z-stability and in particular brings large classes of C*-algebras associated to free and minimal actions…

Operator Algebras · Mathematics 2021-04-07 Jorge Castillejos , Samuel Evington , Aaron Tikuisis , Stuart White , Wilhelm Winter

Model sets play a fundamental role in structure analysis of quasicrystals. The diffraction diagram of a quasicrystal admits as symmetry group a finite group G, and there is a G-cluster C (union of orbits of G) such that the quasicrystal can…

Mathematical Physics · Physics 2007-05-23 Nicolae Cotfas

We analyse the fusion products of certain representations of the Virasoro algebra for c=-2 and c=-7 which are not completely reducible. We introduce a new algorithm which allows us to study the fusion product level by level, and we use this…

High Energy Physics - Theory · Physics 2011-05-05 Matthias R. Gaberdiel , Horst G. Kausch

In this paper, we introduce a C*-algebra associated to any substitution (via its Bratteli diagram model). We show that this C*-algebra contains the partial crossed product C*-algebra of the corresponding Bratteli-Vershik system and show…

Operator Algebras · Mathematics 2011-08-24 Daniel Gonçalves , Danilo Royer

We show that the nuclear dimension of a (twisted) group C*-algebra of a virtually polycyclic group is finite. This prompts us to make a conjecture relating finite nuclear dimension of group C*-algebras and finite Hirsch length, which we…

Operator Algebras · Mathematics 2026-01-15 Caleb Eckhardt , Jianchao Wu

The problem of inner vs outer conjugacy of subalgebras of certain graph C*-algebras is investigated. For a large class of finite graphs E, we show that whenever $\alpha$ is a vertex-fixing quasi-free automorphism of the corresponding graph…

Operator Algebras · Mathematics 2022-09-09 Tomohiro Hayashi , Jeong Hee Hong , Sophie Emma Zegers , Wojciech Szymański

We define a broad class of crossed product C*-algebras of the form C(G)xG, where G is a discrete countable amenable residually finite group, and G is a profinite completion of G. We show that they are unital separable simple nuclear…

Operator Algebras · Mathematics 2013-01-22 Stefanos Orfanos

We consider inductive systems of C*-algebras with completely positive contractive connecting maps. We define a condition, called C*-encoding, which is sufficient for the limit of the system to be completely order isomorphic to a C*-algebra…

Operator Algebras · Mathematics 2023-06-26 Kristin Courtney

In this work it is shown that certain interesting types of quasi-orthogonal system of subalgebras (whose existence cannot be ruled out by the trivial necessary conditions) cannot exist. In particular, it is proved that there is no…

Mathematical Physics · Physics 2010-02-02 Mihály Weiner

We give a characterization of extremal irreducible discrete subfactors $(N\subseteq M, E)$ where $N$ is type ${\rm II}_1$ in terms of connected W*-algebra objects in rigid C*-tensor categories. We prove an equivalence of categories where…

Operator Algebras · Mathematics 2018-01-09 Corey Jones , David Penneys

Graded $C^*$-algebras by a semi lattice were introduced and studied by Anne Boutet de Monvel, Vladimir Georgescu and their collaborators in relation with the quantum N body problem. This thesis is devoted to a systematic study of these…

Operator Algebras · Mathematics 2007-05-23 Athina Mageira

We study C*-irreducibility of inclusions of reduced twisted group C*-algebras and of reduced group C*-algebras. We characterize C*-irreducibility in the case of an inclusion arising from a normal subgroup, and exhibit many new examples of…

Operator Algebras · Mathematics 2023-01-31 Erik Bédos , Tron Omland

To a regular projection of a knot we associate a finite dimensional non-commutative associative algebra which is self-injective and special biserial.

Rings and Algebras · Mathematics 2018-06-12 Claude Cibils

In the theory of C*-algebras, interesting noncommutative structures arise as deformations of the tensor product. For instance, the rotation algebra may be seen as a scalar twist deformation of the tensor product of the functions on the…

Operator Algebras · Mathematics 2013-03-04 Moritz Weber

Given an algebra $A$ and an $A-A$-bimodule $U$ with co-algebra structure, a bocs, the algebras of endomorphisms of $A$ as left or right module of the bocs are known as Burt-Butler algebras (up to an appropriate opposite). Here we give a…

Representation Theory · Mathematics 2024-01-29 R. Bautista , J. A. Jimenez Gonzalez

We give a classification result for a certain class of $C^{*}$-algebras $\mathfrak{A}$ over a finite topological space $X$ in which there exists an open set $U$ of $X$ such that $U$ separates the finite and infinite subquotients of…

Operator Algebras · Mathematics 2015-05-28 Soren Eilers , Gunnar Restorff , Efren Ruiz

We exhibit examples of simple separable nuclear C*-algebras, along with actions of the circle group and outer actions of the integers, which are not equivariantly isomorphic to their opposite algebras. In fact, the fixed point subalgebras…

Operator Algebras · Mathematics 2016-02-16 Marius Dadarlat , Ilan Hirshberg , N. Christopher Phillips

We study semiprojective, subhomogeneous C*-algebras and give a detailed description of their structure. In particular, we find two characterizations of semiprojectivity for subhomogeneous C*-algebras: one in terms of their primitive ideal…

Operator Algebras · Mathematics 2017-01-03 Dominic Enders

A self-dual algebras is one isomorphic as a module to the opposite of its dual; a quasi self-dual algebra is one whose cohomology with coefficients in itself is isomorphic to that with coefficients in the opposite of its dual. For these…

K-Theory and Homology · Mathematics 2011-11-03 Murray Gerstenhaber