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Let $G$ be a compact Lie group that acts smoothly on a closed manifold $M$. Using a general Simonenko principle, we derive a novel criterion for the Fredholm property of $G$-pseudodifferential operators acting on Sobolev spaces of sections…

Differential Geometry · Mathematics 2026-05-15 Alexandre Baldare , Anton Yu. Savin , Elmar Schrohe

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

For a limited range of indices $p$, we obtain $L^p(\mathbb{R}^n)$ boundedness for singular integral operators whose kernels satisfy a condition weaker than the typical H\"ormander smoothness estimate. These operators are assumed to be…

Classical Analysis and ODEs · Mathematics 2019-10-23 Loukas Grafakos , Cody B. Stockdale

Let $(X,d)$ be a uniformly locally finite metric space, and $T$ an operator in the uniform Roe algebra $C_u^*(X)$ (or uniform quasi-local algebra $C_{ql}^*(X)$). In this paper, we introduce the concept of limit operators of $T$ on galaxies…

Functional Analysis · Mathematics 2025-09-30 Liang Guo , Jin Qian , Qin Wang

We obtain a necessary and sufficient condition on an exponent $p(\cdot)$ for which the Hardy--Littlewood maximal operator is bounded on the variable $L^{p(\cdot)}$ space. It is formulated in terms of the Muckenhoupt-type condition…

Classical Analysis and ODEs · Mathematics 2023-02-14 Andrei K. Lerner

In this paper we explore some characteristics of the quasi-Fredholm resolvent set $\rho_{qf}(T)$ of an operator $T$ defined on an infinite dimensional Banach space $X$. Moreover, in the case of Hilbert space $H$, we study the stability of…

Spectral Theory · Mathematics 2019-08-13 Anuradha Gupta , Ankit Kumar

We give a criterion for the global boundedness of integral operators which are known to be locally bounded. As an application, we discuss the global $L^p$-boundedness for a class of Fourier integral operators. While the local…

Functional Analysis · Mathematics 2017-11-27 Michael Ruzhansky , Mitsuru Sugimoto

We prove affirmatively the one dimensional case of a conjecture of Stein regarding the $L^p$-boundedness of the Polynomial Carleson operator, for $1<p<\infty$. The proof is based on two new ideas: i) developing a framework for…

Classical Analysis and ODEs · Mathematics 2019-02-12 Victor Lie

We prove boundedness results for integral operators of fractional type and their higher order commutators between weighted spaces, including $L^p$-$L^q$, $L^p$-$BMO$ and $L^p$-Lipschitz estimates. The kernels of such operators satisfy…

Analysis of PDEs · Mathematics 2018-06-29 Estefanía Dalmasso , Gladis Pradolini , Wilfredo Ramos

We investigate complexes of Hilbert C*-modules, which are cochain complexes with (unbounded) regular operators between Hilbert C*-modules as differential maps. In particular, we provide various equivalent characterizations of the Fredholm…

Operator Algebras · Mathematics 2025-05-13 Brian Villegas-Villalpando , Koen van den Dungen

We study the boundedness of the linear operator $S$ on $L^{p}_{a}(dA_{\alpha})$ $(0<p<\infty)$. In particular, we obtain a sufficient and necessary condition for the compactness of the linear operator $S$ on $L^{p}_{a}(dA_{\alpha})$…

Functional Analysis · Mathematics 2025-07-15 Zengjian Lou , Antti Rasila , Senhua Zhu

Recent sampling theorems allow for the recovery of operators with bandlimited Kohn-Nirenberg symbols from their response to a single discretely supported identifier signal. The available results are inherently non-local. For example, we…

Functional Analysis · Mathematics 2013-10-22 Felix Krahmer , Götz Pfander

If $A \colon D(A) \subset \mathcal{H} \to \mathcal{H}$ is an unbounded Fredholm operator of index $0$ on a Hilbert space $\mathcal{H}$ with a dense domain $D(A)$, then its spectrum is either discrete or the entire complex plane. This…

Spectral Theory · Mathematics 2025-10-10 Simon Becker , Izak Oltman , Martin Vogel

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

We characterize lower semi-Fredholm and Fredholm of weighted composition operators on $C(K)$ in the case when the corresponding map is an open surjection of the compact space $K$ onto itself. The obtained criterions involve the notion of…

Functional Analysis · Mathematics 2022-02-09 Arkady Kitover , Mehmet Orhon

We provide Fredholm conditions for compatible differential operators on certain Lie manifolds (that is, on certain possibly non-compact manifolds with nice ends). We discuss in more detail the case of manifolds with cylindrical, hyperbolic,…

Analysis of PDEs · Mathematics 2023-08-14 Ivan Beschastnyi , Catarina Carvalho , Victor Nistor , Yu Qiao

This paper is devoted to the space of unbounded Fredholm operators equipped with the graph topology, the subspace of operators with compact resolvent, and their subspaces consisting of self-adjoint operators. Our main results are the…

K-Theory and Homology · Mathematics 2025-04-17 Marina Prokhorova

In this paper we prove sufficient conditions for the Fredholm property of a non-smooth pseudodifferential operator $P$ which symbol is in a H\"older space with respect to the spatial variable. As a main ingredient for the proof we use a…

Functional Analysis · Mathematics 2018-06-05 Helmut Abels , Christine Pfeuffer

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

For $2a$-order strongly elliptic operators $P$ generalizing $(-\Delta )^a$, $0<a<1$, the treatment of the homogeneous Dirichlet problem on a bounded open set $\Omega \subset R^n$ by pseudodifferential methods, has been extended in a recent…

Analysis of PDEs · Mathematics 2022-12-23 Gerd Grubb
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