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Related papers: A Baum-Connes conjecture for singular foliations

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We introduce a new method for studying the Baum-Connes conjecture, which we call the direct splitting method. The method can simplify and clarify proofs of some of the known cases of the conjecture. In a separate paper, with J. Brodzki, E.…

Operator Algebras · Mathematics 2019-04-08 Shintaro Nishikawa

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

First, we shall formulate and prove Theorem of Lie-Kolchin type for a cone and derive some algebro-geometric consequences. Next, inspired by a recent result of Dinh and Sibony we pose a conjecture of Tits type for a group of automorphisms…

Algebraic Geometry · Mathematics 2018-06-20 JongHae Keum , Keiji Oguiso , De-Qi Zhang

We prove the Baum-Connes conjecture for hyperbolic groups and their subgroups.

Operator Algebras · Mathematics 2009-11-07 Igor Mineyev , Guoliang Yu

Recent discoveries make it possible to compute the K-theory of certain rings from their cyclic homology and certain versions of their cdh-cohomology. We extend the work of G. Corti\~nas et al. who calculated the K-theory of, in addition to…

K-Theory and Homology · Mathematics 2013-11-21 David Wayne

In a previous paper ([1]), we associated a holonomy groupoid and a C*-algebra to any singular foliation (M,F). Using these, we construct the associated pseudodifferential calculus. This calculus gives meaning to a Laplace operator of any…

Differential Geometry · Mathematics 2009-10-09 Iakovos Androulidakis , Georges Skandalis

We give a new proof of some cases of the Baum-Connes conjecture along the lines of a proof of the Farrell-Jones conjecture.

Algebraic Topology · Mathematics 2013-03-05 Fabian Lenhardt

We study general properties of exotic crossed-product functors and characterise those which extend to functors on equivariant C*-algebra categories based on correspondences. We show that every such functor allows the construction of a…

Operator Algebras · Mathematics 2015-07-07 Alcides Buss , Siegfried Echterhoff , Rufus Willett

We extend the concept of orbifold to that of branchfold, in order to allow any cone singularities with rational angles, and show why branchfolds naturally fit in the theory of branched coverings. Then, we obtain a geometric goodness theorem…

Geometric Topology · Mathematics 2008-06-20 Riccardo Piergallini , Giacomo Tomassoni

This article studies codimension one foliations on projective man-ifolds having a compact leaf (free of singularities). It explores the interplay between Ueda theory (order of flatness of the normal bundle) and the holo-nomy representation…

Classical Analysis and ODEs · Mathematics 2018-08-31 Benoît Claudon , Frank Loray , Jorge Pereira , Frédéric Touzet

Replaces Previous version. Includes comments on poincare duality for twisted equivariant in the context of proper and discrete actions and the Baum-Connes Conjecture. We use a spectral sequence proposed by C. Dwyer and previous work by…

K-Theory and Homology · Mathematics 2013-08-23 Noe Barcenas , Mario Velasquez

Given an ample groupoid, we construct a spectral sequence with groupoid homology with integer coefficients on the second sheet, converging to the K-groups of the (reduced) groupoid C*-algebra, provided the groupoid has torsion-free…

K-Theory and Homology · Mathematics 2022-07-12 Valerio Proietti , Makoto Yamashita

This note provides a counterexample showing that the assumptions that Chabert and Echterhoff have imposed in their permanence property of the Baum-Connes conjecture for group extensions cannot be simplified.

K-Theory and Homology · Mathematics 2026-02-25 Ralf Meyer

We give a superconnection proof of Connes' index theorem for proper cocompact actions of etale groupoids. This includes Connes' general foliation index theorem for foliations with Hausdorff holonomy groupoid.

Differential Geometry · Mathematics 2007-05-23 Alexander Gorokhovsky , John Lott

We give a new construction of the holonomy and fundamental groupoids of a singular foliation. In contrast with the existing construction of Androulidakis and Skandalis, our method proceeds by taking a quotient of an infinite dimensional…

Differential Geometry · Mathematics 2021-06-15 Joel Villatoro , Alfonso Garmendia

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

In this paper we study the Lie groupoids which appear in foliation theory. A foliation groupoid is a Lie groupoid which integrates a foliation, or, equivalently, whose anchor map is injective. The first theorem shows that, for a Lie…

K-Theory and Homology · Mathematics 2007-05-23 M. Crainic , I. Moerdijk

Transversally K\"ahler foliations are a generalisation of K\"ahler manifolds, appearing naturally in the complex non-K\"ahler setting. We give a self-contained proof of how the classical methods used in the proof of the Aubin-Yau theorem…

Differential Geometry · Mathematics 2025-06-05 Vlad Marchidanu

In this article we study the cohomological and homological (due to Jannsen) Hodge conjecture for singular varieties. The motivation for studying singular varieties comes from the fact that any smooth projective variety X is birational to a…

Algebraic Geometry · Mathematics 2025-10-01 Ananyo Dan , Inder Kaur

These lecture notes attempt to invite the reader towards the theory of singular foliations, both smooth and holomorphic. In addition to a systematic review of the foundations, and an attempt to put in order examples and several elementary…

Differential Geometry · Mathematics 2024-11-21 Camille Laurent-Gengoux , Ruben Louis , Leonid Ryvkin
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