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We consider the equivariant Kasparov category associated to an \'etale groupoid, and by leveraging its triangulated structure we study its localization at the "weakly contractible" objects, extending previous work by R. Meyer and R. Nest.…

K-Theory and Homology · Mathematics 2024-12-23 Christian Bönicke , Valerio Proietti

Using the concept of a cohesive module defined by Block, we use the theory of superconnections in the sense of Quillen to construct natural superconnections on Hermitian cohesive modules. By the Chern-Weil construction, we obtain…

Differential Geometry · Mathematics 2016-11-15 Hua Qiang

To every tree we associate a filtered cochain complex. Its cohomology and the corresponding spectral sequence have clear combinatorial description. If a tree is the Dynkin diagram of a simple plane curve singularity, the graded Euler…

Combinatorics · Mathematics 2009-01-12 E. Gorsky

We use correspondences to define a purely topological equivariant bivariant K-theory for spaces with a proper groupoid action. Our notion of correspondence differs slightly from that of Connes and Skandalis. We replace smooth K-oriented…

K-Theory and Homology · Mathematics 2012-06-29 Heath Emerson , Ralf Meyer

In this paper we prove that the linear Koszul duality isomorphism for convolution algebras in K-homology defined in a previous paper and the Fourier transform isomorphism for convolution algebras in Borel-Moore homology are related by the…

Representation Theory · Mathematics 2015-09-15 Ivan Mirkovic , Simon Riche

We study deformation of algebras with coaction symmetry of reduced algebra of discrete groups, where the deformation parameter is given continuous family of group $2$-cocycles. When the group satisfies the Baum-Connes conjecture with…

Operator Algebras · Mathematics 2023-08-07 Makoto Yamashita

We provide an equivariant extension of Carlsson's BGG correspondence in characteristic two. As an application we classify perfect cochain complexes of $(\mathbb{Z}/2\times \mathbb{Z}/2)\rtimes Q$-representations with four-dimensional total…

Commutative Algebra · Mathematics 2024-04-17 Henrik Rüping , Marc Stephan

We show that equivariant K-theory satisfies descent with respect to the isovariant Nisnevich topology. The main step is to show that the isovariant Nisnevich topology is a regular, complete and bounded cd topology.

K-Theory and Homology · Mathematics 2010-02-15 Christian Serpe

We report in this survey some new results concerning noncommutative Chern characters: construction and the cases when they are exactly computed. The major result indicates some clear relation of these noncommutative objects and their…

Quantum Algebra · Mathematics 2007-05-23 Do Ngoc Diep

We define N-theory being some analogue of K-theory on the category of von Neumann algebras such that $K_0(A)\subset N_0(A)$ for any von Neumann algebra A. Moreover, it turns out to be possible to construct the extension of the Chern…

Operator Algebras · Mathematics 2007-05-23 A. A. Pavlov

We use bisection to provide an algebraic proof that the Chern form on the convolution algebra of an \'etale groupoid is closed.

Differential Geometry · Mathematics 2024-07-23 Wen Zhang

For a toric variety X_P determined by a rational polyhedral fan P in a lattice N, Payne shows that the equivariant Chow cohomology of X_P is the Sym(N)--algebra C^0(P) of integral piecewise polynomial functions on P. We use the…

Algebraic Geometry · Mathematics 2014-07-14 Hal Schenck

In characteristic zero, Bezrukavnikov has shown that the category of perverse coherent sheaves on the nilpotent cone of a simply connected semisimple algebraic group is quasi-hereditary, and that it is derived-equivalent to the category of…

Representation Theory · Mathematics 2011-09-14 Pramod N. Achar

This paper is the second part of a series of papers on noncommutative geometry and conformal geometry. In this paper, we compute explicitly the Connes-Chern character of an equivariant Dirac spectral triple. The formula that we obtain for…

Differential Geometry · Mathematics 2017-03-17 Raphael Ponge , Hang Wang

Using a global version of the equivariant Chern character, we describe the complexified twisted equivariant K-theory of a space with a compact Lie group action in terms of fixed-point data. We apply this to the case of a compact Lie group…

Algebraic Topology · Mathematics 2014-02-26 Daniel S. Freed , Michael J. Hopkins , Constantin Teleman

This paper investigates the $\mathrm{K}$-theory of twisted groupoid $\mathrm{C}^*$-algebras. It is shown that a homotopy of twists on an ample groupoid satisfying the Baum-Connes conjecture with coefficients gives rise to an isomorphism…

Operator Algebras · Mathematics 2019-04-25 Christian Bönicke

We generalize Kontsevich's construction of L-infinity derivations of polyvector fields from the affine space to an arbitrary smooth algebraic variety. More precisely, we construct a map (in the homotopy category) from Kontsevich's graph…

K-Theory and Homology · Mathematics 2015-02-09 Vasily Dolgushev , Christopher L. Rogers , Thomas Willwacher

For a two-periodic complex of vector bundles, Polishchuk and Vaintrob have constructed its localized Chern character. We explore some basic properties of this localized Chern character. In particular, we show that the cosection localization…

Algebraic Geometry · Mathematics 2021-11-18 Bumsig Kim , Jeongseok Oh

The third author recently proved that the Shoikhet-Dolgushev L-infinity-morphism from Hochschild chains of the algebra of smooth functions on manifold to differential forms extends to cyclic chains. Localization at a solution of the…

Quantum Algebra · Mathematics 2014-01-16 Alberto S. Cattaneo , Giovanni Felder , Thomas Willwacher

A `total Chern class' invariant of knots is defined. This is a universal Vassiliev invariant which is integral `on the level of Lie algebras' but it is not expressible as an integer sum of diagrams. The construction is motivated by…

Geometric Topology · Mathematics 2014-10-01 Simon Willerton