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We show that elements of unital $C^*$-algebras without tracial states are finite sums of commutators. Moreover, the number of commutators involved is bounded, depending only on the given $C^*$-algebra.

Functional Analysis · Mathematics 2007-05-23 Ciprian Pop

An example is given of a simple, unital C*-algebra which contains an infinite and a non-zero finite projection. This C*-algebra is also an example of an infinite simple C*-algebra which is not purely infinite. A corner of this C*-algebra is…

Operator Algebras · Mathematics 2010-11-24 Mikael Rordam

We generalize Amitsur's construction of central simple algebras over a field $F$ which are split by field extensions possessing a derivation with field of constants $F$ to nonassociative algebras: for every central division algebra $D$ over…

Rings and Algebras · Mathematics 2021-04-13 Susanne Pumpluen

We show that finitely generated subhomogeneous C*-algebras have finite decomposition rank. As a consequence, any separable ASH C*-algebra can be written as an inductive limit of subhomogeneous C*-algebras each of which has finite…

Operator Algebras · Mathematics 2007-05-23 Ping Wong Ng , Wilhelm Winter

We exhibit examples of actions of countable discrete groups on both simple and non-simple nuclear stably finite C*-algebras that are tracially amenable but not amenable. We furthermore obtain that, under the additional assumption of strict…

Operator Algebras · Mathematics 2024-08-21 Eusebio Gardella , Julian Kranz , Andrea Vaccaro

By reducing a split $G_2$ Kac-Moody algebra by a non-maximal set of first-class constraints we produce W-algebras which (i) contain fields of negative conformal spin and (ii) are not trivial extensions of canonical W-algebras.

High Energy Physics - Theory · Physics 2009-10-28 G. A. T. F. da Costa , L. O'Raifeartaigh

By studying NIM-representations we show that the Fibonacci category and its tensor powers are completely anisotropic; that is, they do not have any non-trivial separable commutative ribbon algebras. As an application we deduce that a chiral…

Category Theory · Mathematics 2011-03-21 Alexei Davydov , Tom Booker

We present a classification theorem for a class of unital simple separable amenable ${\cal Z}$-stable $C^*$-algebras by the Elliott invariant. This class of simple $C^*$-algebras exhausts all possible Elliott invariant for unital stably…

Operator Algebras · Mathematics 2015-11-17 Guihua Gong , Huaxin Lin , Zhuang Niu

We give two characterizations of tracially nuclear C*-algebras. The first is that the finite summand of the second dual is hyperfinite. The second is in terms of a variant of the weak* uniqueness property. The necessary condition holds for…

Operator Algebras · Mathematics 2018-10-15 Don Hadwin , Weihua Li , Wenjing Liu , Junhao Shen

Using Effros-Handelman-Shen theorem and Elliott's classification theorem of AF algebras, we show that there exists a unital simple AF algebra A with unique trace such that $A\otimes \mathbb{K}$ admits no trace scaling action of the…

Operator Algebras · Mathematics 2011-09-09 Norio Nawata

The aim of this paper is to introduce and study Lie algebras and Lie groups over noncommutative rings. For any Lie algebra $\gg$ sitting inside an associative algebra $A$ and any associative algebra $\FF$ we introduce and study the algebra…

Quantum Algebra · Mathematics 2008-02-19 Arkady Berenstein , Vladimir Retakh

Axial algebras are commutative nonassociative algebras generated by a finite set of primitive idempotents which action on an algebra is semisimple, and the fusion laws on the products between eigenvectors for these idempotents are…

Rings and Algebras · Mathematics 2025-08-20 Ilya Gorshkov , Vsevolod Gubarev

Tensor models are the generalization of matrix models, and are studied as models of quantum gravity in general dimensions. In this paper, I discuss the algebraic structure in the fuzzy space interpretation of the tensor models which have a…

High Energy Physics - Theory · Physics 2015-05-27 Naoki Sasakura

We introduce the fundamental group F(A) of a simple $\sigma$-unital $C^*$-algebra $A$ with unique (up to scalar multiple) densely defined lower semicontinuous trace. This is a generalization of our previous works. Our definition in this…

Operator Algebras · Mathematics 2010-08-30 Norio Nawata

We show that the following divisible properties of the ${\rm C^*}$-algebras in a class $\mathcal{P}$ are inherited by simple unital ${\rm C^*}$-algebras in the class of asymptotically tracially in $\mathcal{P}$: $(1)$ $m$-almost divisible,…

Operator Algebras · Mathematics 2024-04-08 Qingzhai Fan , Jiahui Wang

This note is to show the effectiveness of the notion of pseudoalgebra in the theory of conformal algebras. We adduce very simple construction of free associative conformal algebra and find its linear basis. There is no any new result but we…

Quantum Algebra · Mathematics 2007-05-23 Pavel Kolesnikov

We define the twisted affine Yangian of type $C$ and construct surjective homomorphisms from twisted affine Yangians of type $C$ to the universal enveloping algebra of the rectangular $W$-algebra associated with $\mathfrak{so}(ln)$ and a…

Quantum Algebra · Mathematics 2022-03-02 Mamoru Ueda

We classify the Fibonacci chains (F-chains) by their index sequences and construct an approximately finite dimensional (AF) $C^*$-algebra on the space of F-chains as Connes did on the space of Penrose tiling. The K-theory on this AF-algebra…

Mathematical Physics · Physics 2009-10-31 Hyeong-Chai Jeong , Eunsang Kim , Chang-Yeong Lee

We go on with the definition of the theory of the non--Abelian two--tensor fields and find the gauge transformation rules and curvature tensor for them. To define the theory we use the surface {\it exponent} proposed in hep--th/0503234. We…

High Energy Physics - Theory · Physics 2007-05-23 Emil T. Akhmedov

The algebraic conditions that specific gauged G/H-WZW model have to satisfy in order to give rise to Non-Abelian Toda models with singular metric with or without torsion are found. The classical algebras of symmetries corresponding to grade…

High Energy Physics - Theory · Physics 2016-09-06 J. F. Gomes , F. E. Mendonça da Silveira , G. M. Sotkov , A. H. Zimerman