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We relate the spectral flow to the index for paths of selfadjoint Breuer-Fredholm operators affiliated to a semifinite von Neumann algebra, generalizing results of Robbin-Salamon and Pushnitski. Then we prove the vanishing of the von…

Differential Geometry · Mathematics 2011-04-28 Sara Azzali , Charlotte Wahl

We consider an action of the real line on a C*-algebra for which there is a centre-valued invariant trace. We define a family of Toeplitz operators with symbols in the original algebra. When the symbol is invertible, the Toeplitz operator…

Operator Algebras · Mathematics 2019-08-15 John Phillips , Iain Raeburn

We extend the relative index theorem on non-compact manifolds to encompass a wide variety of hypoelliptic differential operators of arbitrary order, demonstrating that the change in index when changing a differential operator locally can be…

K-Theory and Homology · Mathematics 2025-11-11 Magnus Fries

We generalise the local index formula of Connes and Moscovici to the case of spectral triples for a *-subalgebra \A of a general semifinite von Neumann algebra. In this setting it gives a formula for spectral flow along a path joining an…

Operator Algebras · Mathematics 2007-05-23 Alan L. Carey , John Phillips , Adam Rennie , Fyodor A. Sukochev

Based on operators borrowed from scattering theory, several concrete realizations of index theorems are proposed. The corresponding operators belong to some C*-algebras of pseudo-differential operators with coefficients which either have…

Mathematical Physics · Physics 2017-11-21 H. Inoue , S. Richard

We give a definition of the spectral flow for paths of bounded essentially hyperbolic operators on a Banach space. The spectral flow induces a group homomorphism on the fundamental group of every connected component of the space of…

Functional Analysis · Mathematics 2011-03-10 Garrisi Daniele

We establish a formula for the spectral flow of a smooth family of twisted Dirac operators on a closed odd-dimensional Riemannian spin manifold, generalizing a result by Getzler. The spectral flow is expressed in terms of the $\hat{A}$-form…

Differential Geometry · Mathematics 2025-12-05 Christian Baer , Remo Ziemke

A formula is given in terms of secondary characteristic classes for the leading order contribution to the spectral flow for a path of twisted Dirac operators on an odd dimensional, Riemannian manifold when the twisting is done by a path of…

Differential Geometry · Mathematics 2007-05-23 Clifford Henry Taubes

We survey the notion of the spectral shift function of a pair of self-adjoint operators and recent progress on its connection with the Witten index. We also describe a proof of Krein's Trace Theorem that does not use complex analysis [53]…

Spectral Theory · Mathematics 2015-05-20 Alan Carey , Fritz Gesztesy , Galina Levitina , Fedor Sukochev

Motivated by Fredholm theory, we develop a framework to establish the convergence of spectral methods for operator equations $\mathcal L u = f$. The framework posits the existence of a left-Fredholm regulator for $\mathcal L$ and the…

Numerical Analysis · Mathematics 2024-04-24 Thomas Trogdon

In this paper we show the invariance of the Fredholm index of non-smooth pseudodifferential operators with coefficients in H\"older spaces. By means of this invariance we improve previous spectral invariance results for non-smooth…

Functional Analysis · Mathematics 2020-09-24 Helmut Abels , Christine Pfeuffer

The spectral flow is a classical notion of functional analysis and differential geometry which was given different interpretations as Fredholm index, Witten index, and Maslov index. The classical theory treats spectral flow outside the…

Spectral Theory · Mathematics 2015-02-03 Nurulla Azamov

In this paper, we define an analytical index for a continuous family of Fredholm operators parameterized by a topological space $\mathbb{X}$ into a Hilbert space $H,$ as a sequence of integers, extending naturally the usual definition of…

Spectral Theory · Mathematics 2020-10-28 Mohammed Berkani

We define a spectral flow for paths of selfadjoint Fredholm operators that are equivariant under the orthogonal action of a compact Lie group as an element of the representation ring of the latter. This $G$-equivariant spectral flow shares…

Functional Analysis · Mathematics 2021-04-06 Marek Izydorek , Joanna Janczewska , Nils Waterstraat

Toeplitz operators on spaces $H^p(G)\ (1< p<\infty)$ associated with compact connected Abelian group $G$ with ordered dual are considered and the generalization of the classical Gohberg-Krein theorem on the Fredholm index of such operators…

Functional Analysis · Mathematics 2019-12-10 A. R. Mirotin

We introduce the notion of the joint spectral flow, which is a generalization of the spectral flow, by using Segal's model of the connective $K$-theory spectrum. We apply it for some localization results of indices motivated by Witten's…

K-Theory and Homology · Mathematics 2016-01-20 Yosuke Kubota

In this paper a definition is given for an unbounded Toeplitz-like operator with rational symbol which has poles on the unit circle. It is shown that the operator is Fredholm if and only if the symbol has no zeroes on the unit circle, and a…

Functional Analysis · Mathematics 2020-02-21 G. J. Groenewald , S. ter Horst , J. Jaftha , A. C. M. Ran

We consider a continuous curve of self-adjoint Fredholm extensions of a curve of closed symmetric operators with fixed minimal domain $D_m$ and fixed {\it intermediate} domain $D_W$. Our main example is a family of symmetric generalized…

Differential Geometry · Mathematics 2007-05-23 Bernhelm Booss-Bavnbek , Chaofeng Zhu

We show that the Dirac operator on a compact globally hyperbolic Lorentzian spacetime with spacelike Cauchy boundary is a Fredholm operator if appropriate boundary conditions are imposed. We prove that the index of this operator is given by…

Differential Geometry · Mathematics 2019-10-01 Christian Baer , Alexander Strohmaier

Let $D_t$, $t \in [0,1]$ be an arbitrary 1-parameter family of Dirac type operators on a two-dimensional disk with $m-1$ holes. Suppose that all operators $D_t$ have the same symbol, and that $D_1$ is conjugate to $D_0$ by a scalar gauge…

Mathematical Physics · Physics 2013-07-17 Marina Prokhorova