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Given a C*-algebra B, a closed *-subalgebra A contained in B, and a partial isometry S in B which "interacts" with A in the sense that S*aS = H(a)S*S and SaS* = V(a)SS*, where V and H are positive linear operators on A, we derive a few…

Operator Algebras · Mathematics 2010-03-16 Ruy Exel

In this paper we show that the Cuntz algebra can be represented as a C*-crossed product by endomorphism of the canonical anticommutation relations (CAR) algebra, generated by the standard recursive fermion system.

Operator Algebras · Mathematics 2014-04-04 Marat Aukhadiev , Alexander Nikitin , Airat Sitdikov

In this survey, we study the relations between amenability (resp. amenability at infinity) of C*-dynamical systems and equality or nuclearity (resp. exactness) of the corresponding crossed products.

Operator Algebras · Mathematics 2007-05-23 C. Anantharaman-Delaroche

In the first part of the paper, we develop a theory of crossed products of a $C^*$-algebra $A$ by an arbitrary (not necessarily extendible) endomorphism $\alpha:A\to A$. We consider relative crossed products $C^*(A,\alpha;J)$ where $J$ is…

Operator Algebras · Mathematics 2016-12-01 B. K. Kwasniewski

We examine the semicrossed products of a semigroup action by $*$-endomorphisms on a C*-algebra, or more generally of an action on an arbitrary operator algebra by completely contractive endomorphisms. The choice of allowable representations…

Operator Algebras · Mathematics 2018-08-17 Kenneth R. Davidson , Adam H. Fuller , Evgenios T. A. Kakariadis

A groupoid correspondence on an etale, locally compact groupoid induces a C*-correspondence on its groupoid C*-algebra. We show that the Cuntz-Pimsner algebra for this C*-correspondence relative to an ideal associated to an open invariant…

Operator Algebras · Mathematics 2026-05-20 Ralf Meyer

Given a cocycle on a topological quiver by a locally compact group, the author constructs a skew product topological quiver, and determines conditions under which a topological quiver can be identified as a skew product. We investigate the…

Operator Algebras · Mathematics 2024-11-20 Lucas Hall

Let $n$ be a positive integer. We introduce a concept, which we call the $n$-filling property, for an action of a group on a separable unital $C^*$-algebra $A$. If $A=C(\Omega)$ is a commutative unital $C^*$-algebra and the action is…

Operator Algebras · Mathematics 2013-02-25 P. Jolissaint , G. Robertson

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

We study the exactness of the reduced crossed product of a semigroup dynamical system and the reduced $C^{*}$-algebra of a product system. We show that for a semigroup dynamical system $(A, P,\alpha)$, under reasonable hypotheses (e.g., $P$…

Operator Algebras · Mathematics 2026-04-07 Md Amir Hossain , S. Sundar

We give a new definition for the crossed-product of a C*-algebra A by a *-endomorphism \alpha, which depends not only on the pair (A,\alpha) but also on the choice of a transfer operator (defined in the paper). With this we generalize some…

Operator Algebras · Mathematics 2007-05-23 Ruy Exel

A braided category of C*-algebras is constructed. Its objects are C*-algebras endowed with an action of the group R, its morphisms are C*-algebras morphisms intertwining the action of R, the crossed product of its two objects essentially…

q-alg · Mathematics 2009-10-30 Malgorzata Rowicka-Kudlicka

In this paper, we give some properties of the fixed point algebra and the crossed product of a unital separable simple infinite dimensional C*-algebra by an action of a second-countable compact group with the tracial Rokhlin property with…

Operator Algebras · Mathematics 2025-07-08 Haotian Tian , Xiaochun Fang

Using Kirchberg-Phillips' classification of purely infinite C*-algebras by K-theory, we prove that the isomorphism types of crossed product C*-algebras associated to certain hyperbolic 3-manifold groups acting on their Gromov boundary only…

Operator Algebras · Mathematics 2024-08-07 Shirly Geffen , Julian Kranz

Let $\M=P\times{M}$ be a variable Mautner group. We describe the $C^*$-algebra $C^*(\M)$ of $\M$ in terms of an algebra of operator fields defined over $P\times{\C^2} $.

Operator Algebras · Mathematics 2021-03-19 Hedi Regeiba

We describe both the Bunce-Deddens C*-algebras and their Toeplitz versions, as crossed products of commutative C*-algebras by partial automorphisms. In the latter case, the commutative algebra has, as its spectrum, the union of the Cantor…

funct-an · Mathematics 2008-02-03 Ruy Exel

We analyze Hecke pairs (G,H) and the associated Hecke algebra when G is a semidirect product N x Q and H = M x R for subgroups M of N and R of Q with M normal in N. Conditions are given in terms of N, Q, M, and R which are equivalent to the…

Operator Algebras · Mathematics 2008-04-11 S. Kaliszewski , Magnus B. Landstad , John Quigg

We show that if (A,a) and (B,b) are automorphic multivariable C*-dynamical systems with isometrically isomorphic tensor algebras (or semi crossed products), then the systems are piecewise conjugate over their Jacobson spectrum. This answers…

Operator Algebras · Mathematics 2016-02-16 Elias Katsoulis

Let G be a compact group. Let (X,G) be a standard Borel G-measure space. We show that the group action on (X, G) is transitive if and only if it is ergodic. Using this result, we show that every irreducible covariant representation of a…

Operator Algebras · Mathematics 2011-04-13 Firuz Kamalov

We characterize Cuntz-Nica-Pimsner algebras for compactly aligned product systems over quasi-lattice ordered groupoids. We show that the full cross sectional $C^*$-algebras of Fell bundles of Morita equivalence bimodules are isomorphic to…

Operator Algebras · Mathematics 2023-05-09 Feifei Miao , Liguang Wang , Wei Yuan