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We first introduce an invariant index for G-equivariant elliptic differential operators on a locally compact manifold M admitting a proper cocompact action of a locally compact group G. It generalizes the Kawasaki index for orbifolds to the…

Differential Geometry · Mathematics 2014-11-18 Varghese Mathai , Weiping Zhang

We define and study an equivariant version of Farber's topological complexity for spaces with a given compact group action. This is a special case of the equivariant sectional category of an equivariant map, also defined in this paper. The…

Algebraic Topology · Mathematics 2014-10-01 Hellen Colman , Mark Grant

Let $D$ be a (generalized) Dirac operator on a non-compact complete Riemannian manifold $M$ acted on by a compact Lie group $G$. Let $v:M --> Lie(G)$ be an equivariant map, such that the corresponding vector field on $M$ does not vanish…

Mathematical Physics · Physics 2007-05-23 Maxim Braverman

Consider a proper, isometric action by a unimodular locally compact group $G$ on a Riemannian manifold $M$ with boundary, such that $M/G$ is compact. For an equivariant, elliptic operator $D$ on $M$, and an element $g \in G$, we define a…

Differential Geometry · Mathematics 2021-10-26 Peter Hochs , Bai-Ling Wang , Hang Wang

We study equivariant projective compactifications of reductive groups obtained by closing the image of a group in the space of operators of a projective representation. We describe the structure and the mutual position of their orbits under…

Algebraic Geometry · Mathematics 2015-06-26 Dmitri A. Timashev

Problems of dense and closed extension of actions of compact transformation groups are solved. The method developed in the paper is applied to problems of extension of equivariant maps and of construction of equivariant compactifications.

General Topology · Mathematics 2011-08-08 Sergei M. Ageev , Dušan Repovš

We formulate and prove an index theorem for loop spaces of compact manifolds in the framework of $KK$-theory. It is a strong candidate for the noncommutative geometrical definition (or the analytic counterpart) of the Witten genus. In order…

K-Theory and Homology · Mathematics 2022-08-26 Doman Takata

We construct an equivariant version of Ray-Singer analytic torsion for proper, isometric actions by locally compact groups on Riemannian manifolds, with compact quotients. We obtain results on convergence, metric independence, vanishing for…

Differential Geometry · Mathematics 2023-06-30 Peter Hochs , Hemanth Saratchandran

We define a notion of equivariant non-degeneracy of $G$-maps to introduce the class of equivariantly non-degenerate flows on smooth compact manifolds with compact Lie group action. We prove genericity of this class and use this result to…

Dynamical Systems · Mathematics 2013-01-31 Philipp Wruck

Given a proper, cocompact action of a Lie groupoid, we define a higher index pairing between invariant elliptic differential operators and smooth groupoid cohomology classes. We prove a cohomological index formula for this pairing by…

Differential Geometry · Mathematics 2014-06-06 M. J. Pflaum , H. Posthuma , X. Tang

Starting from any proper action of any locally compact quantum group on any discrete quantum space, we show that its equivariant representation theory yields a concrete unitary 2-category of finite type Hilbert bimodules over the discrete…

Operator Algebras · Mathematics 2025-08-27 Lukas Rollier

Recently, two of the authors of this paper constructed cyclic cocycles on Harish-Chandra's Schwartz algebra of linear reductive Lie groups that detect all information in the $K$-theory of the corresponding group $C^*$-algebra. The main…

Differential Geometry · Mathematics 2021-06-30 Peter Hochs , Yanli Song , Xiang Tang

Equivariant versions of the radial index and of the GSV-index of a vector field or a 1-form on a singular variety with an action of a finite group are defined. They have values in the Burnside ring of the group. Poincar\'e-Hopf type…

Algebraic Geometry · Mathematics 2013-07-09 Wolfgang Ebeling , Sabir M. Gusein-Zade

In two previous papers, we started a study of the first eigenvalue of the Dirac operator on compact spin symmetric spaces, providing, for symmetric spaces of "inner" type, a formula giving this first eigenvalue in terms of the algebraic…

Differential Geometry · Mathematics 2019-09-19 Jean-Louis Milhorat

We construct a regularized index of a generalized Dirac operator on a complete Riemannian manifold endowed with a proper action of a unimodular Lie group. We show that the index is preserved by a certain class of non-compact cobordisms and…

Differential Geometry · Mathematics 2015-12-09 Maxim Braverman

Many index theorems (both classical and in noncommutative geometry) can be interpreted in terms of a Lie groupoid acting properly on a manifold and leaving an elliptic family of pseudodifferential operators invariant. Alain Connes in his…

Operator Algebras · Mathematics 2007-05-23 Alan L. T. Paterson

Many index theorems (both classical and in noncommutative geometry) can be interpreted in terms of a Lie groupoid acting properly on a manifold and leaving an elliptic family of pseudodifferential operators invariant. Alain Connes in his…

Operator Algebras · Mathematics 2007-05-23 Alan L. T. Paterson

We give a framework of localization for the index of a Dirac-type operator on an open manifold. Suppose the open manifold has a compact subset whose complement is covered by a family of finitely many open subsets, each of which has a…

Differential Geometry · Mathematics 2015-03-13 Hajime Fujita , Mikio Furuta , Takahiko Yoshida

In this expository article, we consider first order elliptic differential operators acting on smooth vector bundles over compact manifolds, and certain invariants derived from the analysis of these operators, namely the eta invariant} and…

Differential Geometry · Mathematics 2019-08-15 Jochen Brüning , Ken Richardson

A Dirac operator on a complete manifold is Fredholm if it is invertible outside a compact set. Assuming a compact group to act on all relevant structure, and the manifold to have a warped product structure outside such a compact set, we…

Differential Geometry · Mathematics 2023-03-20 Peter Hochs , Hang Wang