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The K-theoretic analog of Spanier-Whitehead duality for noncommutative C*-algebras is shown to hold for the Ruelle algebras associated to irreducible Smale spaces. This had previously been proved only for shifts of finite type. Implications…

K-Theory and Homology · Mathematics 2017-09-25 Jerome Kaminker , Ian F. Putnam , Michael F. Whittaker

Given an ample Hausdorff groupoid $G$, a unital commutative ring $R$, and a discrete twist $(\Sigma,i,q)$, we establish a generalised uniqueness theorem for the twisted Steinberg algebra $A_R(G;\Sigma)$. By applying this theorem when $G$ is…

Rings and Algebras · Mathematics 2026-05-13 Rizalyn S. Bongcawel , Lyster Rey B. Cabardo , Lisa O. Clark

Let X be a proper hyperbolic geodesic metric space and let G be a closed subgroup of the isometry group Iso(X) of X. We show that if G is not amenable then its second continuous bounded cohomology group with coefficients the regular…

Group Theory · Mathematics 2008-03-16 Ursula Hamenstadt

We develop a theory of \emph{strongly quasiconvex subgroups} of an arbitrary finitely generated group. Strong quasiconvexity generalizes quasiconvexity in hyperbolic groups and is preserved under quasi-isometry. We show that strongly…

Group Theory · Mathematics 2019-06-05 Hung Cong Tran

We introduce twisted Steinberg algebras over a commutative unital ring $R$. These generalise Steinberg algebras and are a purely algebraic analogue of Renault's twisted groupoid C*-algebras. In particular, for each ample Hausdorff groupoid…

Rings and Algebras · Mathematics 2022-06-06 Becky Armstrong , Lisa Orloff Clark , Kristin Courtney , Ying-Fen Lin , Kathryn McCormick , Jacqui Ramagge

The twisted Connes-Moscovici higher index theorem is generalized to the case of good orbifolds. The higher index is shown to be a rational number, and in fact non-integer in specific examples of 2-orbifolds. This results in a…

Differential Geometry · Mathematics 2007-05-23 Matilde Marcolli , Varghese Mathai

In this paper, we introduce a concept of A-by-FCE coarse fibration structure for metric spaces, which serves as a generalization of the A-by-CE structure for a sequence of group extensions proposed by Deng, Wang, and Yu. We prove that the…

K-Theory and Homology · Mathematics 2025-01-22 Liang Guo , Qin Wang , Chen Zhang

We develop a finite KKG-theory of C*-algebras following Arlettaz- H.Inassaridze's approach to finite algebraic K-theory. The Browder- Karoubi-Lambre's theorem on the orders of the elements for finite algebraic K-theory is extended to finite…

K-Theory and Homology · Mathematics 2009-10-01 Hvedri Inassaridze , Tamaz Kandelaki

The outlines of a "Galois theory" for bimeromorphic geometry is here developed, via the study of model-theoretic definable binding groups in the theory CCM of compact complex spaces. As an application, a structure theorem about principal…

Logic · Mathematics 2025-12-15 Rahim Moosa , Anand Pillay

A hyperbolic group acts by homeomorphisms on its Gromov boundary. We use a dynamical coding of boundary points to show that such actions are topologically stable in the dynamical sense: any nearby action is semi-conjugate to (and an…

Group Theory · Mathematics 2023-08-21 Kathrynn Mann , Jason Fox Manning , Theodore Weisman

A sequence $(a_{n}) $ in an Abelian group is called a $T$-sequence if there exists a Hausdorff group topology on $G$ in which $(a_{n}) $ converges to $0$. For a $T$-sequence $(a_{n}) $, $\tau_{(a_{n}) } $ denotes the strongest group…

General Topology · Mathematics 2019-02-07 D. Dikranjan , I. Protasov

We study a coarse homology theory with prescribed growth conditions. For a finitely generated group G with the word length metric this homology theory turns out to be related to amenability of G. We characterize vanishing of a certain…

Group Theory · Mathematics 2011-08-09 Piotr Nowak , Jan Spakula

We show that the Baum-Connes morphism twisted by a non-unitary representation, defined in [GA08], is an isomorphism for a large class of groups satisfying the Baum-Connes conjecture. Such class contains all the real semi-simple Lie groups,…

K-Theory and Homology · Mathematics 2008-04-29 Maria-Paula Gomez-Aparicio

We define and compare two bivariant generalizations of the topological $K$-group $K^\top(G)$ for a topological group $G$. We consider the Baum-Connes conjecture in this context and study its relation to the usual Baum-Connes conjecture.

K-Theory and Homology · Mathematics 2011-10-18 Otgonbayar Uuye

We present a geometric approach to the Baum-Connes conjecture with coefficients for Gromov monster groups via a theorem of Khoskham and Skandalis. Secondly, we use recent results concerning the a-T-menability at infinity of large girth…

K-Theory and Homology · Mathematics 2014-09-23 Martin Finn-Sell

We prove the Borel Conjecture for a class of groups containing word-hyperbolic groups and groups acting properly, isometrically and cocompactly on a finite dimensional CAT(0)-space.

Geometric Topology · Mathematics 2010-03-26 Arthur Bartels , Wolfgang Lueck

We prove the existence of continuous boundary extensions (Cannon-Thurston maps) for the inclusion of a vertex space into a tree of (strongly) relatively hyperbolic spaces satisfying the qi-embedded condition. This implies the same result…

Group Theory · Mathematics 2011-03-24 Mahan Mj , Abhijit Pal

In this note, we exhibit a method to prove the Baum-Connes conjecture (with coefficients) for extensions with finite quotients of certain groups which already satisfy the Baum-Connes conjecture. Interesting examples to which this method…

K-Theory and Homology · Mathematics 2014-11-11 Thomas Schick

Using methods from coarse topology we show that fundamental classes of closed enlargeable manifolds map non-trivially both to the rational homology of their fundamental groups and to the K-theory of the corresponding reduced C*-algebras.…

Algebraic Topology · Mathematics 2018-11-28 B. Hanke , D. Kotschick , J. Roe , T. Schick

We prove that torsion-freeness in the sense of Meyer-Nest is preserved under divisible discrete quantum subgroups. As a consequence, we obtain some stability results of the torsion-freeness property for relevant constructions of quantum…

Operator Algebras · Mathematics 2024-12-30 Rubén Martos