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We study the Spectral Analysis for a class of bounded linear operators T = D + F in a non Archimedean Hilbert space E, where D is a diagonal linear operator and where F is a finite rank linear operator. In this study of the Spectral…

Functional Analysis · Mathematics 2022-11-30 Teylama Miabey

In the present article, we study the discrete spectrum of certain bounded Toeplitz operators with harmonic symbol on a Bergman space. Using the methods of classical perturbaton theory and recent results by Borichev-Golinskii-Kupin and…

Spectral Theory · Mathematics 2022-04-28 Leonid Golinskii , Stanislas Kupin , Juliette Leblond , Masimba Nemaire

The quantized Hall conductance in a plateau is related to the index of a Fredholm operator. In this paper we describe the generic ``phase diagram'' of Fredholm indices associated with bounded and Toeplitz operators. We discuss the possible…

Mathematical Physics · Physics 2009-10-31 Joseph E. Avron , Lorenzo Sadun

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

In this paper, first we investigate closed range multiplication conditional type operators between two Lp-spaces. Then we characterize Fredholm ones when the underlying measure space is non-atomic. Finally we give some examples.

Functional Analysis · Mathematics 2015-03-10 Yousef Estaremi

The aim of this note is to generalize the notion of Fredholm operator to an arbitrary $C^*$-algebra. Namely, we define "finite type" elements in an axiomatic way, and also we define Fredholm type element $a$ as such element of a given…

Operator Algebras · Mathematics 2018-01-09 Dragoljub J. Kečkić , Zlatko Lazović

We prove novel results on interpolation of Fredholm operators including an abstract factorization theorem. The main result of this paper provides sufficient conditions on the parameters $\theta \in (0,1)$ and $q\in \lbrack 1,\infty ]$ under…

Functional Analysis · Mathematics 2014-09-01 I. Asekritova , N. Kruglyak , M. Mastyło

In this paper, we address the existence of Fredholm backstepping transformations for self-adjoint and skew-adjoint operators $A$. Under suitable assumptions on the operator $A$ and the possibly unbounded control operator $B$, we prove the…

Optimization and Control · Mathematics 2026-05-19 Ludovick Gagnon , Amaury Hayat , Swann Marx , Shengquan Xiang , Christophe Zhang

Let $M$ be a temporal compact globally hyperbolic manifold with Cauchy hypersurface $\Sigma$ which is a Galois covering with respect to a discrete group $\Gamma$ of automorphisms such that the quotient $\Sigma/\Gamma$ is compact without…

Differential Geometry · Mathematics 2024-10-02 Orville Damaschke

We study the stability of Fredholm property for regular operators on Hilbert $C^*$-modules under some certain perturbations. We treat this problem when perturbing operators are (relatively) bounded or relatively compact. We also consider…

Operator Algebras · Mathematics 2017-02-21 Marzieh Forough

This paper is devoted to establishing the kernel theorems for $\alpha$-modulation spaces in terms of boundedness and compactness. We characterize the boundedness of a linear operator $A$ from an $\alpha$-modulation space…

Functional Analysis · Mathematics 2024-10-01 Guoping Zhao , Weichao Guo

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 prove the spectral mapping theorem $\sigma_e(A_\phi) = \phi(\sigma_e(A_z))$ for the Fredholm spectrum of a truncated Toeplitz operator $A_\phi$ with symbol $\phi$ in the Sarason algebra $C+H^\infty$ acting on a coinvariant subspace…

Complex Variables · Mathematics 2022-02-28 R. V. Bessonov

Withdrawn due to a likely error with the homeomorphism at line (4). Old abstract: In the monograph 'Limit Operators and their Applications in Operator Theory', the authors define the operator spectrum of a band-dominated operator T and…

Functional Analysis · Mathematics 2008-07-05 Rufus Willett

We show that layer potential groupoids for conical domains constructed in an earlier paper (Carvalho-Qiao, Central European J. Math., 2013) are Fredholm groupoids, which enables us to deal with many analysis problems on singular spaces in a…

Operator Algebras · Mathematics 2018-07-17 Catarina Carvalho , Yu Qiao

In this paper the concept of unbounded Fredholm operators on Hilbert C*- modules over an arbitrary C*-algebra is discussed and the Atkinson theorem is generalized for bounded and unbounded Feredholm operators on Hilbert C*-modules over…

Operator Algebras · Mathematics 2015-06-26 Assadollah Niknam , Kamran Sharifi

This paper is a self-contained presentation of certain aspects of the theory of weighted Sobolev spaces and elliptic operators on non-compact Riemannian manifolds. Specifically, we discuss (i) the standard and weighted Sobolev Embedding…

Differential Geometry · Mathematics 2010-05-20 Tommaso Pacini

A version of Arzel\`a-Ascoli theorem for $X$ being $\sigma$-locally compact Hausdorff space is proved. The result is used in proving compactness of Fredholm, Hammerstein and Urysohn operators. Two fixed point theorems, for Hammerstein and…

Functional Analysis · Mathematics 2015-05-12 Mateusz Krukowski , Bogdan Przeradzki

In 1970s Segal outlined proofs of two theorems relating spaces of Fredholm and self-adjoint Fredholm operators with Quillen's constructions used to define higher algebraic K-theory. In the present paper we provide detailed proofs of these…

K-Theory and Homology · Mathematics 2023-02-09 Nikolai V. Ivanov

We use quantum harmonic analysis for densely defined operators to provide a simplified proof of the Berger-Coburn theorem for boundedness of Toeplitz operators. In addition, we revisit compactness and Schatten-class membership of densely…

Functional Analysis · Mathematics 2025-08-20 Vishwa Dewage , Mishko Mitkovski