English
Related papers

Related papers: Crossed product by an arbitrary endomorphism

200 papers

We show that the $\ell^p$-pseudofunctions, which were recently shown to lead to exotic completions of group $C^*$-algebras by Wiersma and the second named author, can be used to construct well-behaved crossed product functors in the sense…

Operator Algebras · Mathematics 2026-04-30 Jacek Krajczok , Ebrahim Samei , Timo Siebenand , Adam Skalski

We consider a certain class of unital simple stably finite C^*-algebras which absorb the Jiang-Su algebra Z tensorially. Under a mild assumption, we show that the crossed product of a C^*-algebra in this class by a strongly outer action of…

Operator Algebras · Mathematics 2011-07-05 Hiroki Matui , Yasuhiko Sato

For dynamical systems defined by a covering map of a compact Hausdorff space and the corresponding transfer operator, the associated crossed product $C^*$-algebras $\cros$ introduced by Exel and Vershik are considered. An important property…

Operator Algebras · Mathematics 2014-10-10 Toke Meier Carlsen , Sergei Silvestrov

We establish comparison and divisibility properties for crossed product C*-algebras arising from automorphisms of algebras C (X, D) which lie over minimal homeomorphisms, from actions of compact groups which have finite Rokhlin dimension…

Operator Algebras · Mathematics 2026-04-14 Dawn Archey , Julian Buck , Javad Mohammadkarimi , N. Christopher Phillips , Apurva Seth

We consider Exel's interaction $(V,H)$ over a unital $C^*$-algebra $A$, such that $V(A)$ and $H(A)$ are hereditary subalgebras of $A$. For the associated crossed product, we obtain a uniqueness theorem, ideal lattice description, simplicity…

Operator Algebras · Mathematics 2014-11-27 B. K. Kwaśniewski

We prove that a number of classes of separable unital C*-algebras are closed under crossed products by finite group actions with the Rokhlin property, including: (1) AI algebras, AT algebras, and related classes characterized by direct…

Operator Algebras · Mathematics 2009-02-06 Hiroyuki Osaka , N. Christopher Phillips

Let $X$ be compact Hausdorff, and $\phi: X \to X$ a continuous surjection. Let $\mathcal{A}$ be the semicrossed product algebra corresponding to the relation $fU = Uf\circ \phi$. Then the C$^*$-envelope of $\mathcal{A}$ is the crossed…

Operator Algebras · Mathematics 2007-05-23 Justin R. Peters

The $K$-groups of the crossed product of the rotation C*-algebra $A_\theta$ by free and amalgamated products of the cyclic groups $\mathbb Z_n$, for $n=2,3,4,6$, are calculated. The actions here arise from the canonical actions of these…

Operator Algebras · Mathematics 2018-09-26 Sam Walters

Let $X$ be compact Hausdorff, and $\phi: X \to X$ a continuous surjection. Let $\mathcal{A}$ be the semicrossed product algebra corresponding to the relation fU = Uf\circ \phi$ or to the relation $Uf = f\circ \phi U.$ Then the…

Operator Algebras · Mathematics 2008-10-31 Justin R. Peters

It was shown by Rordam and the second named author that a countable group G admits an action on a compact space such that the crossed product is a Kirchberg algebra if, and only if, G is exact and non-amenable. This construction allows a…

Operator Algebras · Mathematics 2011-11-01 G. A. Elliott , A. Sierakowski

A product system E over a semigroup P is a family of Hilbert spaces {E_s:s\in P} together with multiplications E_s \times E_t\to E_{st}. We view E as a unitary- valued cocycle on P, and consider twisted crossed products A \times_{\beta,E} P…

funct-an · Mathematics 2008-02-03 N. Fowler , I. Raeburn

We consider separable $C^*$-dynamical systems $(A,G,\alpha)$ for which the induced action of the group $G$ on the spectrum $\hat A$ of the $C^*$-algebra $A$ is free. We study how the representation theory of the associated crossed-product…

Operator Algebras · Mathematics 2014-02-26 Robert Archbold , Astrid an Huef

We introduce a method to study C*-algebras possessing an action of the circle group, from the point of view of its internal structure and its K-theory. Under relatively mild conditions our structure Theorem shows that any C*-algebra, where…

funct-an · Mathematics 2016-08-31 Ruy Exel

Let P be a semigroup that admits an embedding into a group G. Assume that the embedding satisfies a certain Toeplitz condition and that the Baum-Connes conjecture holds for G. We prove a formula describing the K- theory of the reduced…

Operator Algebras · Mathematics 2012-05-25 Joachim Cuntz , Siegfried Echterhoff , Xin Li

This paper characterizes the unital C*-algebra generated by a single invertible element as the unital free product of C[0,1] and C(T). To do this, I develop techniques to split and merge presentations of C*-algebras using free products in…

Operator Algebras · Mathematics 2011-10-04 Will Grilliette

The C*-algebra of a skew-product topological graph is a crossed product of the C*-algebra of the base topological graph by a coaction.

Operator Algebras · Mathematics 2013-01-15 S. Kaliszewski , John Quigg

A C*-dynamical system is said to have the ideal separation property if every ideal in the corresponding crossed product arises from an invariant ideal in the C*-algebra. In this paper we characterize this property for unital C*-dynamical…

Operator Algebras · Mathematics 2019-12-19 Matthew Kennedy , Christopher Schafhauser

The crossed products of locally C*-algebras are defined and a Takai duality theorem for inverse limit actions of a locally compact group on a locally C*-algebra is proved.

Operator Algebras · Mathematics 2007-05-23 Maria Joita

We analyze existence of crossed product constructions of Lie group actions on C^*-algebras which are singular. These are actions where the group need not be locally compact, or the action need not be strongly continuous. In particular, we…

Operator Algebras · Mathematics 2020-07-30 Hendrik Grundling , Karl-Hermann Neeb

All crossed products of two cyclic groups are explicitly described using generators and relations. A necessary and sufficient condition for an extension of a group by a group to be a cyclic group is given.

Group Theory · Mathematics 2014-02-24 Ana-Loredana Agore , Dragos Fratila