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Let X be a closed connected contact manifold. On X there is a naturally arising class of hypoelliptic (but not elliptic) operators which are Fredholm. In this paper we solve the index problem for this class of operators. The solution is…

Operator Algebras · Mathematics 2012-12-07 Paul F. Baum , Erik van Erp

A hypoelliptic operator in the Heisenberg calculus on a compact contact manifold is a Fredholm operator. Its symbol determines an element in the K-theory of the noncommutative algebra of Heisenberg symbols. We construct a periodic cyclic…

Operator Algebras · Mathematics 2020-10-07 Alexander Gorokhovsky , Erik van Erp

We show that the computation of the Fredholm index of a fully elliptic pseudodifferential operator on an integrated Lie manifold can be reduced to the computation of the index of a Dirac operator, perturbed by a smoothing operator,…

K-Theory and Homology · Mathematics 2022-04-20 Karsten Bohlen , Jean-Marie Lescure

We present a new solution to the index problem for hypoelliptic operators in the Heisenberg calculus on contact manifolds, by constructing the appropriate topological K-theory cocycle for such operators. Its Chern character gives a…

Differential Geometry · Mathematics 2010-07-28 Erik van Erp

We prove index formulas for elliptic operators acting between sections of C*-vector bundles on a closed manifold. The formulas involve Karoubi's Chern character from K-theory of a C*-algebra to de Rham homology of smooth subalgebras. We…

K-Theory and Homology · Mathematics 2009-01-03 Charlotte Wahl

We generalize Roe's Index Theorem for operators of Dirac type on open manifolds to elliptic pseudodifferential operators. To this end we introduce a class of pseudodifferential operators on manifolds of bounded geometry which is more…

Differential Geometry · Mathematics 2014-10-30 Alexander Engel

This research comprehensively describes the basic theory of transversally Heisenberg elliptic operators, and investigates the index theory of Heisenberg elliptic and transversally Heisenberg elliptic operators from the perspective of…

K-Theory and Homology · Mathematics 2025-01-22 Minjie Tian

This is an expository article. It discusses an approach to hypoelliptic Fredholm index theory based on noncommutative methods (groupoids, C*-algebras, K-theory). The paper starts with an explicit index theorem for scalar second order…

Differential Geometry · Mathematics 2015-05-18 Erik van Erp

We prove an index theorem for inhomogeneous differential operators satisfying the Rockland condition (hence hypoelliptic). This theorem extends an index theorem for contact manifolds by Van-Erp.

K-Theory and Homology · Mathematics 2020-01-03 Omar Mohsen

Boutet de Monvel's calculus provides a pseudodifferential framework which encompasses the classical differential boundary value problems. In an extension of the concept of Lopatinski and Shapiro, it associates to each operator two symbols:…

K-Theory and Homology · Mathematics 2018-11-28 Severino Melo , Elmar Schrohe , Thomas Schick

The extended Heisenberg algebra for a contact manifold has a symbolic calculus that accommodates both Heisenberg pseudodifferential operators as well as classical pseudodifferential operators. We derive here a formula for the index of…

Functional Analysis · Mathematics 2010-08-24 Erik van Erp

Let M be a foliated manifold and G a discrete group acting on M by diffeomorphisms mapping leaves to leaves. Then G naturally acts by automorphisms on the algebra of Heisenberg pseudodifferential operators on the foliation. Our main result…

K-Theory and Homology · Mathematics 2016-12-09 Denis Perrot , Rudy Rodsphon

This is an expository paper which gives a proof of the Atiyah-Singer index theorem for elliptic operators. Specifcally, we compute the geometric K-cycle that corresponds to the analytic K-cycle determined by the operator. This paper and its…

Differential Geometry · Mathematics 2016-11-21 Paul Baum , Erik van Erp

In this paper we study the following question: do sub-Laplacian type operators have non-trivial index theory on Carnot manifolds in higher degree of nilpotency? The problem relates to characterizing the structure of the space of…

Analysis of PDEs · Mathematics 2025-01-29 Magnus Goffeng , Bernard Helffer

Given a contact sub-Riemannian manifold one obtains a non-integrable splitting of the tangent bundle into the directions along the contact distribution and the Reeb field. We generalize the construction of the Bismut superconnection to this…

Mathematical Physics · Physics 2025-10-29 Jesus Sanchez , Andres Franco Valiente

The Atiyah-Singer index theorem is a topological formula for the index of an elliptic differential operator. The topological index depends on a cohomology class that is constructed from the principal symbol of the operator. On contact…

Differential Geometry · Mathematics 2010-07-28 Erik van Erp

We introduce a simplified (coarse) version of pseudo-differential calculus for operators of order zero on complete Riemannian manifolds. This calculus works for the usual Hormander (1,0) class of operators, as well as for…

Differential Geometry · Mathematics 2025-06-19 Gennadi Kasparov

It is well known that elliptic operators on a smooth compact manifold are classified by K-homology. We prove that a similar classification is also valid for manifolds with simplest singularities: isolated conical points and fibered…

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

We establish an $\mathrm{L}^p$-index theorem for Dolbeault--Dirac operators on compact K\"ahler manifolds with coefficients in a Hermitian holomorphic vector bundle $E$. For every $p \in (1,\infty)$, we prove that the closed…

Functional Analysis · Mathematics 2026-05-21 Cédric Arhancet

This is an expository paper which gives a proof of the Atiyah-Singer index theorem for Dirac operators, presenting the theorem as a computation of the K-homology of a point. This paper and its follow up ("K-homology and index theory II:…

Differential Geometry · Mathematics 2016-04-13 Paul Baum , Erik van Erp
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