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Related papers: A K-theoretic note on the spectral localiser

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We describe the index pairing between an odd K-theory class and an odd unbounded Kasparov module by a pair of quasi-projections, supported on a submodule obtained from a finite spectral truncation. We achieve this by pairing the K-theory…

K-Theory and Homology · Mathematics 2026-04-01 Yuezhao Li , Bram Mesland

Even index pairings are integer-valued homotopy invariants combining an even Fredholm module with a $K_0$-class specified by a projection. Numerous classical examples are known from differential and non-commutative geometry and physics.…

Mathematical Physics · Physics 2018-02-14 Terry Loring , Hermann Schulz-Baldes

Odd index pairings of $K_1$-group elements with Fredholm modules are of relevance in index theory, differential geometry and applications such as to topological insulators. For the concrete setting of operators on a Hilbert space over a…

Mathematical Physics · Physics 2017-08-04 Terry Loring , Hermann Schulz-Baldes

The spectral localizer, introduced by Loring in 2015 and Loring and Schulz-Baldes in 2017, is a method to compute the (infinite volume) topological invariant of a quantum Hamiltonian on $\ZZ^d$, as the signature of the (finite) localizer…

Mathematical Physics · Physics 2025-12-29 Gregory Berkolaiko , Jacob Shapiro , Beyer Chase White

The notion of spectral localizer is extended to pairings with semifinite spectral triples. By a spectral flow argument, any semifinite index pairing is shown to be equal to the signature of the spectral localizer. As an application, a…

Mathematical Physics · Physics 2020-08-06 Hermann Schulz-Baldes , Tom Stoiber

An odd Fredholm module for a given invertible operator on a Hilbert space is specified by an unbounded so-called Dirac operator with compact resolvent and bounded commutator with the given invertible. Associated to this is an index pairing…

Mathematical Physics · Physics 2018-05-29 Terry Loring , Hermann Schulz-Baldes

We study the index homomorphism of even K-groups arising from a class in even KK-theory via the Kasparov product. Due to the seminal work of Baaj and Julg, under mild conditions on the C^*-algebras in question such a class in KK-theory can…

K-Theory and Homology · Mathematics 2025-08-13 Jens Kaad

In this paper we begin a study of the space of unbounded self-adjoint Fredholm operators as a classifying space for K^{1}(X), with the goal of incorporating the information in the eigenspaces and eigenvalues of the operators. In particular,…

K-Theory and Homology · Mathematics 2008-05-31 Ronald G. Douglas , Jerome Kaminker

We give a comprehensive account of an analytic approach to spectral flow along paths of self-adjoint Breuer-Fredholm operators in a type $I_{\infty}$ or $II_\infty$ von Neumann algebra ${\mathcal N}$. The framework is that of {\it odd…

K-Theory and Homology · Mathematics 2007-05-23 Alan L. Carey , John Phillips

We present a definition of spectral flow relative to any norm closed ideal J in any von Neumann algebra N. Given a path D(t) of selfadjoint operators in N which are invertible in N/J, the spectral flow produces a class in K_0(J). In the…

Operator Algebras · Mathematics 2007-05-23 Jens Kaad , Ryszard Nest , Adam Rennie

Given an essentially unitary contraction and an arbitrary unitary dilation of it, there is a naturally associated spectral flow which is shown to be equal to the index of the operator. This purely operator theoretic result is interpreted in…

Mathematical Physics · Physics 2019-08-15 Giuseppe De Nittis , Hermann Schulz-Baldes

Let M be an even dimensional compact Riemannian manifold with boundary and let D be a Dirac operator acting on the sections of the Clifford module E over M. We impose certain local elliptic boundary conditions for D obtaining a selfadjoint…

Analysis of PDEs · Mathematics 2017-03-10 Alexander Gorokhovsky , Matthias Lesch

We describe a class of real Banach manifolds, which classify $K^{-1}$. These manifolds are Grassmannians of (hermitian) lagrangian subspaces in a complex Hilbert space. Certain finite codimensional real subvarieties described by incidence…

Differential Geometry · Mathematics 2009-03-23 Daniel Cibotaru

We produce a variety of odd bounded Fredholm modules and odd spectral triples on Cuntz-Krieger algebras by means of realizing these algebras as "the algebra of functions on a non-commutative space" coming from a sub shift of finite type. We…

K-Theory and Homology · Mathematics 2015-03-02 Magnus Goffeng , Bram Mesland

Let {D_x} be a family of unbounded self-adjoint Fredholm operators representing an element of K^1(M). Consider the first two components of the Chern character of the family. It is known that these correspond to the spectral flow of the…

K-Theory and Homology · Mathematics 2012-02-08 Ronald G. Douglas , Jerome Kaminker

The method of using periodic approximations to compute the spectral decomposition of the Koop- man operator is generalized to the class of measure-preserving flows on compact metric spaces. It is shown that the spectral decomposition of the…

Dynamical Systems · Mathematics 2018-06-28 Nithin Govindarajan , Ryan Mohr , Shivkumar Chandrasekaran , Igor Mezić

We give a construction of an odd spectral triple on the Cuntz algebra $O_{N}$, whose $K$-homology class generates the odd $K$-homology group $K^1(O_{N})$. Using a metric measure space structure on the Cuntz-Renault groupoid, we introduce a…

Operator Algebras · Mathematics 2018-08-17 Magnus Goffeng , Bram Mesland

Real index pairings of projections and unitaries on a separable Hilbert space with a real structure are defined when the projections and unitaries fulfill symmetry relations invoking the real structure, namely projections can be real,…

Mathematical Physics · Physics 2021-08-17 Nora Doll , Hermann Schulz-Baldes

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

We establish two spectral sequences in knot Floer homology associated to a directed strongly invertible knot K: one from the knot Floer homology of K to a two dimensional vector space, and one from the singular knot Floer homology of a…

Geometric Topology · Mathematics 2024-08-27 Aakash Parikh
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