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Related papers: On a Cuntz-Krieger functor

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We prove a `Whitney' presentation, and a `Coulomb branch' presentation, for the torus equivariant quantum K theory of the Grassmann manifold $\mathrm{Gr}(k;n)$, inspired from physics, and stated in an earlier paper. The first presentation…

Algebraic Geometry · Mathematics 2025-09-05 Wei Gu , Leonardo C. Mihalcea , Eric Sharpe , Hao Zou

We define the categorical cohomology of a k-graph \Lambda\ and show that the first three terms in this cohomology are isomorphic to the corresponding terms in the cohomology defined in our previous paper. This leads to an alternative…

Operator Algebras · Mathematics 2013-08-15 Alex Kumjian , David Pask , Aidan Sims

KK-theory is a bivariant and homotopy-invariant functor on $C^*$-algebras that combines K-theory and K-homology. KK-groups form the morphisms in a triangulated category. Spanier-Whitehead K-Duality intertwines the homological with the…

Operator Algebras · Mathematics 2026-01-08 Ulrich Pennig , Taro Sogabe

We define the relative Cuntz-Krieger algebras associated to finitely aligned higher-rank graphs. We prove versions of the gauge-invariant uniqueness theorem and the Cuntz-Krieger uniqueness theorem for relative Cuntz-Krieger algebras.

Operator Algebras · Mathematics 2007-05-23 Aidan Sims

We associate to each unital $C^*$-algebra $A$ a geometric object---a diagram of topological spaces representing quotient spaces of the noncommutative space underlying $A$---meant to serve the role of a generalized Gel'fand spectrum. After…

Operator Algebras · Mathematics 2014-08-07 Nadish de Silva

In the present paper we study some homotopy invariants which can be defined by means of bundles with fiber a matrix algebra. We also introduce some generalization of the Brauer group in the topological context and show that any its element…

Algebraic Topology · Mathematics 2007-05-23 A. V. Ershov

In this paper, we develop twisted $K$-theory for stacks, where the twisted class is given by an $S^1$-gerbe over the stack. General properties, including the Mayer-Vietoris property, Bott periodicity, and the product structure $K^i_\alpha…

K-Theory and Homology · Mathematics 2007-05-23 Jean-Louis Tu , Ping Xu , Camille Laurent-Gengoux

We introduce a method for producing congruences between Hecke eigenclasses, possibly torsion, in the coherent cohomology of automorphic vector bundles on certain good reduction Shimura varieties. The congruences are produced using some…

Number Theory · Mathematics 2015-07-22 George Boxer

We associate a $C^*$-algebra to a partial action of the integers acting on the base space of a vector bundle, using the framework of Cuntz--Pimsner algebras. We investigate the structure of the fixed point algebra under the canonical gauge…

Operator Algebras · Mathematics 2025-06-23 Aaron Kettner

We introduce twisted relative Cuntz-Krieger algebras associated to finitely aligned higher-rank graphs and give a comprehensive treatment of their fundamental structural properties. We establish versions of the usual uniqueness theorems and…

Operator Algebras · Mathematics 2014-08-07 Aidan Sims , Benjamin Whitehead , Michael F. Whittaker

We present here the K-theoretic version of mirror models of toric manifold. First, we recall the construction of cohomological mirrors for toric manifolds, i.e. representations of the toric hypergeometric functions from quantum cohomology…

Algebraic Geometry · Mathematics 2015-09-28 Alexander Givental

We construct an equivariant coarse homology theory arising from the algebraic $K$-theory of spherical group rings and use this theory to derive split injectivity results for associated assembly maps. On the way, we prove that the…

K-Theory and Homology · Mathematics 2021-05-28 Ulrich Bunke , Daniel Kasprowski , Christoph Winges

We compute the equivariant $K$-homology of the classifying space for proper actions, for compact 3-dimensional hyperbolic reflection groups. This coincides with the topological $K$-theory of the reduced $C^\ast$-algebra associated to the…

K-Theory and Homology · Mathematics 2020-08-05 Jean-François Lafont , Ivonne J. Ortiz , Alexander Rahm , Rubén J. Sánchez-García

Representing Z/N as roots of unity, we restrict a natural U(1)-action on the Heegaard quantum sphere to Z/N, and call the quotient spaces Heegaard quantum lens spaces. Then we use this representation of Z/N to construct an associated…

K-Theory and Homology · Mathematics 2011-10-27 Piotr M. Hajac , Adam Rennie , Bartosz Zielinski

We generalise the theory of Cuntz-Krieger families and graph algebras to the class of finitely aligned $k$-graphs. This class contains in particular all row-finite $k$-graphs. The Cuntz-Krieger relations for non-row-finite $k$-graphs look…

Operator Algebras · Mathematics 2007-05-23 Iain Raeburn , Aidan Sims , Trent Yeend

The aim of this paper is to describe the topological $K$-ring, in terms of generators and relations of a flag Bott manifold. We apply our results to give a presentation for the topological K-ring and hence the Grothendieck ring of algebraic…

Algebraic Topology · Mathematics 2026-01-15 Bidhan Paul , Vikraman Uma

We establish exact sequences in $KK$-theory for graded relative Cuntz-Pimsner algebras associated to nondegenerate $C^*$-correspondences. We use this to calculate the graded $K$-theory and $K$-homology of relative Cuntz-Krieger algebras of…

Operator Algebras · Mathematics 2021-10-26 Quinn Patterson , Adam Sierakowski , Aidan Sims , Jonathan Taylor

Commutative K-theory, a cohomology theory built from spaces of commuting matrices, has been explored in recent work of Adem, G\'{o}mez, Gritschacher, Lind, and Tillman. In this article, we use unstable methods to construct explicit…

Algebraic Topology · Mathematics 2019-06-04 Daniel A. Ramras , Bernardo Villarreal

We study the Pimsner algebra associated with the module of continuous sections of a Hilbert bundle, and prove that it is a continuous bundle of Cuntz algebras. We discuss the role of such Pimsner algebras w.r.t. the notion of inner…

Operator Algebras · Mathematics 2011-11-18 Ezio Vasselli

Twisted complex $K$-theory can be defined for a space $X$ equipped with a bundle of complex projective spaces, or, equivalently, with a bundle of C$^*$-algebras. Up to equivalence, the twisting corresponds to an element of $H^3(X;\Z)$. We…

K-Theory and Homology · Mathematics 2007-05-23 Michael Atiyah , Graeme Segal