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The structure of the spectrum of random operators is studied. It is shown that if the density of states measure of some subsets of the spectrum is zero, then these subsets are empty. In particular follows that absolute continuity of the IDS…

Spectral Theory · Mathematics 2015-06-15 Rafael del Rio

We investigate spectral properties of a 1-dimensional piecewise linear intermittent map, which has not only a marginal fixed point but also a singular structure suppressing injections of the orbits into neighborhoods of the marginal fixed…

Chaotic Dynamics · Physics 2009-11-13 Tomoshige Miyaguchi , Yoji Aizawa

In a variety of contexts, we prove that singular continuous spectrum is generic in the sense that for certain natural complete metric spaces of operators, those with singular spectrum are a dense $G_\delta$.

Spectral Theory · Mathematics 2008-02-03 Rafael del Rio , Svetlana Ya. Jitomirskaya , Nikolai G. Makarov , Barry Simon

We prove and apply two theorems: First, a quantitative, scale-free unique continuation estimate for functions in a spectral subspace of a Schr\"odinger operator on a bounded or unbounded domain, second, a perturbation and lifting estimate…

Spectral Theory · Mathematics 2020-08-18 Ivica Nakić , Matthias Täufer , Martin Tautenhahn , Ivan Veselic , Albrecht Seelmann

We prove new results on the stability of the absolutely continuous spectrum for perturbed Stark operators with decaying or satisfying certain smoothness assumption perturbation. We show that the absolutely continuous spectrum of the Stark…

Spectral Theory · Mathematics 2016-09-07 Alexander Kiselev

We prove that, for an analytic family of ``weakly tame'' regular functions on an affine manifold, the spectrum at infinity of each function of the family is semicontinuous in the sense of Varchenko.

Algebraic Geometry · Mathematics 2011-01-04 Andras Nemethi , Claude Sabbah

Let ${\bf R}$ denote any of the following classes: upper (lower) semi-Fredholm operators, Fredholm operators, upper (lower) semi-Weyl operators, Weyl operators, upper (lower) semi-Browder operators, Browder operators. For a bounded linear…

Functional Analysis · Mathematics 2016-04-27 Miloš D. Cvetković , Snežana Č. Živković-Zlatanović

Let $X$ a Banach space and $T$ a bounded linear operator on $X.$ We denote by $S(T)$ the set of all $\lambda \in \cit$ such that $T$ does not have the single-valued extension property at $\lambda$. In this note we prove equality up to…

Functional Analysis · Mathematics 2009-06-19 M. Amouch , H. Zguitti

We introduce a new topology, weaker than the gap topology, on the space of selfadjoint operators affiliated to a semifinite von Neumann algebra. We define the real-valued spectral flow for a continuous path of selfadjoint Breuer-Fredholm…

Operator Algebras · Mathematics 2007-05-23 Charlotte Wahl

For operators belonging either to a class of global bisingular pseudodifferential operators on $R^m \times R^n$ or to a class of bisingular pseudodifferential operators on a product $M \times N$ of two closed smooth manifolds, we show the…

Analysis of PDEs · Mathematics 2016-03-15 M. Borsero , J. Seiler

We consider discrete one-dimensional Schr\"odinger operators with quasi-Sturmian potentials. We present a new approach to the trace map dynamical system which is independent of the initial conditions and establish a characterization of the…

Mathematical Physics · Physics 2014-12-30 David Damanik , Daniel Lenz

In this paper, we prove that for any $d$-frequency analytic quasiperiodic Schr\"odinger operator, if the frequency is weak Liouvillean, and the potential is small enough, then the corresponding operator has absolutely continuous spectrum.…

Dynamical Systems · Mathematics 2020-04-10 Xuanji Hou , Jing Wang , Qi Zhou

Let $\mathcal{A}$ denote the operator class in which every nonzero intertwiner between two operators in $\mathcal{A}$ has dense range. Utilizing the operators in $\mathcal{A}$ as atoms and the flag structure as connection, we introduce an…

Functional Analysis · Mathematics 2025-08-26 Xie yufang , Ji shanshan , Xu jing , Ji Kui

The classical Weyl-von Neumann theorem states that for any self-adjoint operator $A$ in a separable Hilbert space $\mathfrak H$ there exists a (non-unique) Hilbert-Schmidt operator $C = C^*$ such that the perturbed operator $A+C$ has purely…

Mathematical Physics · Physics 2009-07-06 Mark M. Malamud , Hagen Neidhardt

The existence and construction of periodic approximations with convergent spectra is crucial in solid state physics for the spectral study of corresponding Schr\"odinger operators. In a forthcoming work [9] (arXiv:1709.00975) this task was…

Spectral Theory · Mathematics 2018-03-09 Siegfried Beckus , Jean Bellissard , Giuseppe De Nittis

We show that some spectral properties of the almost Mathieu operator with frequency well approximated by rationals can be as poor as at all possible in the class of all one-dimensional discrete Schroedinger operators. For the class of…

Mathematical Physics · Physics 2023-03-31 Artur Avila , Yoram Last , Mira Shamis , Qi Zhou

The purpose of this paper is to prove that the spectrum of an isotropic Maxwell operator with electric permittivity and magnetic permeability that are periodic along certain directions and tending to a constant super-exponentially fast in…

Mathematical Physics · Physics 2009-11-10 Nikolai Filonov , Frederic Klopp

Almost commutative models provide a framework for Connes' work on the standard model of particle physics. These models are constructed as products of a the canonical spectral triple of a compact connected spin manifold with a finite…

Operator Algebras · Mathematics 2026-03-20 Frederic Latremoliere

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 prove local convergence results for the spectra and pseudospectra of sequences of linear operators acting in different Hilbert spaces and converging in generalised strong resolvent sense to an operator with possibly non-empty essential…

Spectral Theory · Mathematics 2016-05-04 Sabine Bögli