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We establish Fredholm properties for a class of nonlocal differential operators. Using mild convergence and localization conditions on the nonlocal terms, we also show how to compute Fredholm indices via a generalized spectral flow, using…

Analysis of PDEs · Mathematics 2013-06-14 Gregory Faye , Arnd Scheel

In this paper, we extend the class of admissible functions for the trace formula of the second order in the self-adjoint, unitary, and contraction cases for a perturbation in the Hilbert-Schmidt class $\mathcal{S}^2(\mathcal{H})$ by…

Functional Analysis · Mathematics 2024-12-03 Arup Chattopadhyay , Clément Coine , Saikat Giri , Chandan Pradhan

In the paper we consider self-adjoint partial integral operators of Fredholm type $T$ with a degenerate kernel on the space $L_2([a,b]\times[c,d]).$ Essential and discrete spectra of $T$ are described.

Functional Analysis · Mathematics 2015-04-13 Y. K. Eshkavilov , G. P. Arzikulov , F. H. Haydarov

In this paper we show that quasisimilar $n$-tuples of tensor products of $m$-isometric operators have the same spectra, essential spectra and indices. The properties of single Fredholm operators possess \cite{4} is related to an important…

Functional Analysis · Mathematics 2025-10-13 Salah Mecheri

Let $A$ be a linear bounded operator in a Hilbert space $H$, $N(A)$ and $R(A)$ its null-space and range, and $A^*$ its adjoint. The operator $A$ is called Fredholm iff $dim N(A)= dim N(A^*):=n<\infty$ and $R(A)$ and $R(A^*)$ are closed…

Functional Analysis · Mathematics 2007-05-23 A. G. Ramm

Let $\Gamma$ be a compact group acting on a smooth, compact manifold $M$, let $P \in \psi^m(M; E_0, E_1)$ be a $\Gamma$-invariant, classical pseudodifferential operator acting between sections of two equivariant vector bundles $E_i \to M$,…

Differential Geometry · Mathematics 2020-10-01 A. Baldare , R. Côme , M. Lesch , V. Nistor

We study the spectral functional tr f(D+A) for a suitable function f, a self-adjoint operator D having compact resolvent, and a certain class of bounded self-adjoint operators A. Such functionals were introduce by Chamseddine and Connes in…

Functional Analysis · Mathematics 2010-12-16 Walter D. van Suijlekom

The diffusion operator $$ H_D=-\frac12\frac d{dx}a\frac d{dx}-b\frac d{dx}=-\frac12\exp(-2B)\frac d{dx}a\exp(2B)\frac d{dx}, $$ where $B(x)=\int_0^x\frac ba(y)dy$, defined either on $R^+=(0,\infty)$ with the Dirichlet boundary condition at…

Spectral Theory · Mathematics 2008-08-25 Ross G. Pinsky

Burgos, Kaidi, Mbekhta and Oudghiri provided an affirmative answer to a question of Kaashoek and Lay and proved that an operator $F$ is power finite rank if and only if $\sigma_{dsc}(T+F) =\sigma_{dsc}(T)$ for every operator $T$ commuting…

Functional Analysis · Mathematics 2014-03-07 Qingping Zeng , Qiaofen Jiang , Huaijie Zhong

We consider Dirichlet-to-Neumann maps associated with (not necessarily self-adjoint) Schrodinger operators in $L^2(\Omega; d^n x)$, $n=2,3$, where $\Omega$ is an open set with a compact, nonempty boundary satisfying certain regularity…

Spectral Theory · Mathematics 2010-02-04 Fritz Gesztesy , Marius Mitrea , Maxim Zinchenko

Spectral flow was first studied by Atiyah and Lusztig, and first appeared in print in the work of Atiyah-Patodi-Singer (APS). For a norm-continuous path of self-adjoint Fredholm operators in the multiplier algebra $\mathcal{M}(\mathcal{B})$…

Operator Algebras · Mathematics 2024-01-12 Ping Wong Ng , Arindam Sutradhar , Cangyuan Wang

In a previous paper we introduced the unitary conjugation groupoid associated to any unital separable Type I C*-algebra. This groupoid encodes the representation-theoretic structure of the algebra through the action of its unitary group on…

Operator Algebras · Mathematics 2026-03-10 Shih-Yu Chang

We establish a necessary and sufficient criterion for the Fredholmness of a general locally compact band-dominated operator $A$ on $L^p(R)$ and solve the long-standing problem of computing its Fredholm index in terms of the limit operators…

Functional Analysis · Mathematics 2007-05-23 Vladimir S. Rabinovich , Steffen Roch

We introduce the concept of a spectral shift operator and use it to derive Krein's spectral shift function for pairs of self-adjoint operators. Our principal tools are operator-valued Herglotz functions and their logarithms. Applications to…

Spectral Theory · Mathematics 2007-05-23 Fritz Gesztesy , Konstantin A. Makarov , Serguei N. Naboko

The principal aim in this paper is to develop an effective and unified approach to the computation of traces of resolvents (and resolvent differences), Fredholm determinants, $\zeta$-functions, and $\zeta$-function regularized determinants…

Spectral Theory · Mathematics 2022-02-08 Fritz Gesztesy , Klaus Kirsten

Let $\mathcal{A}_0$ and $\mathcal{A}_1$ be two self-adjoint Fredholm Dirac-type operators defined on two non-compact manifolds. If they coincide at infinity so that the relative heat operator is trace-class, one can define their relative…

Differential Geometry · Mathematics 2021-03-01 Pengshuai Shi

In recent years, higher-order trace formulas of operator functions have attracted considerable attention to a large part of the perturbation theory community. In this direction, we prove estimates for traces of higher-order derivatives of…

Functional Analysis · Mathematics 2023-07-25 Arup Chattopadhyay , Saikat Giri , Chandan Pradhan

We revisit the computation of (2-modified) Fredholm determinants for operators with matrix-valued semi-separable integral kernels. The latter occur, for instance, in the form of Green's functions associated with closed ordinary differential…

Spectral Theory · Mathematics 2007-05-23 Fritz Gesztesy , Konstantin A. Makarov

We study discrete Schroedinger operators with compactly supported potentials on the square lattice. Constructing spectral representations and representing S-matrices by the generalized eigenfunctions, we show that the potential is uniquely…

Spectral Theory · Mathematics 2011-09-14 Hiroshi Isozaki , Evgeny Korotyaev

We prove that if T is an operator on an infinite-dimensional Hilbert space whose spectrum and essential spectrum are both connected and whose Fredholm index is only 0 or 1, then the only nontrivial norm-stable invariant subspaces of T are…

Functional Analysis · Mathematics 2010-08-20 Alexander Borichev , Don Hadwin , Hassan Yousefi