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We show that the character from the bivariant K-theory KE^G introduced by Dumitrascu to E^G factors through Kasparov's KK^G for any locally compact group G. Hence KE^G contains KK^G as a direct summand.

K-Theory and Homology · Mathematics 2016-10-31 Ralf Meyer

We outline a proof of a geometric version of the Satake isomorphism. Given a connected, complex algebraic reductive group G we show that the tensor category of representations of the dual group $\check G$ is naturally equivalent to a…

alg-geom · Mathematics 2008-02-03 Ivan Mirković , Kari Vilonen

We introduce property $(T_{Schur},G,K)$ and prove it for some non-cocompact lattice in $Sp_4$ in a local field of finite characteristic. We show that property $(T_{Schur},G,K)$ for a non-cocompact lattice $\Gamma$ in a higher rank almost…

Operator Algebras · Mathematics 2014-11-25 Benben Liao

Every hyperbolic group acts continuously on its Gromov boundary. One can form the corresponding cross-product C*-algebra A. We show that there always exists a canonical Poincare duality map from the K-theory of A to the K-homology of A. We…

K-Theory and Homology · Mathematics 2010-09-28 Heath Emerson

Strongly self-absorbing $\mathrm{C}^*$-algebras play a distinguished role in the classification of nuclear $\mathrm{C}^*$-algebras. Their dynamical analogues were introduced and extensively studied by Szab\'o. In this paper, we propose a…

Operator Algebras · Mathematics 2026-03-16 Masaki Izumi , Keiya Ohara

We revisit the computation, due to Hesselholt and Madsen, of the K-theory of truncated polynomial algebras for perfect fields of positive characteristic. The resulting K-groups are expressed in terms of big Witt vectors of the field. The…

K-Theory and Homology · Mathematics 2020-03-02 Martin Speirs

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 provide a new computation of the K-theory of the group $C^*$-algebra of the solvable Baumslag-Solitar group $BS(1,n)\;(n\neq 1)$; our computation is based on the Pimsner-Voiculescu 6-terms exact sequence, by viewing $BS(1,n)$ as a…

Operator Algebras · Mathematics 2016-04-20 Sanaz Pooya , Alain Valette

For an $r$-discrete Hausdorff groupoid ${\cal G}$ and an inverse semigroup $S$ of slices of ${\cal G}$ there is an isomorphism between ${\cal G}$-equivariant $KK$-theory and compatible $S$-equivariant $KK$-theory. We use it to define…

K-Theory and Homology · Mathematics 2012-11-22 Bernhard Burgstaller

We associate a non-commutative $C^*$-algebra with any locally finite simplicial complex. We determine the $K$-theory of these algebras and show that they can be used to obtain a conceptual explanation for the Baum-Connes conjecture.

Operator Algebras · Mathematics 2007-05-23 Joachim Cuntz

In this note we set a configuration space description of the equivariant connective K-homology groups with coefficients in a unital C*-algebra for proper actions. Over this model we define a connective assembly map and prove that in this…

K-Theory and Homology · Mathematics 2019-02-04 Mario Velásquez

Alain Connes and Nigel Higson pointed out in the 1990s that the Connes-Kasparov "conjecture"' for the K-theory of reduced groupe $C^\ast$-algebras seemed, in the case of reductive Lie groups, to be a cohomological echo of a conjecture of…

Operator Algebras · Mathematics 2021-03-10 Alexandre Afgoustidis

Using the Baum-Connes conjecture with coefficients, we develop a K-theory formula for reduced C*-algebras of strongly $0$-$E$-unitary inverse semigroups, or equivalently, for certain reduced partial crossed products. In the case of…

Operator Algebras · Mathematics 2021-09-15 Xin Li

We associate to every $G$-bornological coarse space $X$ and every left-exact $\infty$-category with $G$-action a left-exact infinity-category of equivariant $X$-controlled objects. Postcomposing with algebraic K-theory leads to {new}…

K-Theory and Homology · Mathematics 2024-03-14 Ulrich Bunke , Denis-Charles Cisinski , Daniel Kasprowski , Christoph Winges

We investigate the relative assembly map from the family of finite subgroups to the family of virtually cyclic subgroups for the algebraic $K$-theory of twisted group rings of a group G with coefficients in a regular ring R or, more…

K-Theory and Homology · Mathematics 2024-08-02 Wolfgang Lueck

This survey deals with the construction of a category of spectral triples that is compatible with the Kasparov product in $KK$-theory. These notes serve as an intuitive guide to these results, avoiding the necessary technical proofs. We…

K-Theory and Homology · Mathematics 2013-04-16 Bram Mesland

The descent method is one of the approaches to study the Brauer--Manin obstruction to the local--global principle and to weak approximation on varieties over number fields, by reducing the problem to ``descent varieties''. In recent lecture…

Algebraic Geometry · Mathematics 2026-01-21 Nguyen Manh Linh

In this paper, we generalize the Dirac-dual-Dirac method to Hecke pairs with equivariant coarse embeddings and establish the K-theoretic isomorphisms between the maximal and reduced equivariant Roe algebras. We also extend these results to…

K-Theory and Homology · Mathematics 2026-02-03 Liang Guo , Hang Wang , Xiufeng Yao

We show that the classical Baum-Connes assembly map is quantitatively an isomorphism for a class of lacunary hyperbolic groups, and we explain how to see that this class contains many examples of groups that contain graph sequences of large…

Group Theory · Mathematics 2026-05-14 Martin Finn-Sell

Making use of topological periodic cyclic homology, we extend Grothendieck's standard conjectures of type C and D (with respect to crystalline cohomology theory) from smooth projective schemes to smooth proper dg categories in the sense of…

Algebraic Geometry · Mathematics 2018-04-26 Goncalo Tabuada