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Relative observability has been introduced and studied in the framework of partially observed discrete-event systems as a condition stronger than observability, but weaker than normality. However, unlike observability, relative…

Optimization and Control · Mathematics 2014-04-09 Jan Komenda , Tomáš Masopust , Jan H. van Schuppen

We introduce and study a new class of operators that we call disjoint weak Banach-Saks operators. We establish some characterizations of this class of operators by different types of convergence (norm convergence, unbounded order…

Functional Analysis · Mathematics 2021-11-30 Mohamed Berka , Moulay othman Aboutafail , Jawad H'michane

In this paper, we characterize absolute norm-attainability for compact hyponormal operators. We give necessary and sufficient conditions for a bounded linear compact hyponormal operator on an infinite dimensional complex Hilbert space to be…

Functional Analysis · Mathematics 2019-03-29 Benard Okelo

In this article, we study absolutely norm attaining operators ($\mathcal{AN}$-operators, in short), that is, operators that attain their norm on every non-zero closed subspace of a Hilbert space. Our focus is primarily on positive…

Functional Analysis · Mathematics 2025-07-16 Puspendu Nag , Ramesh Golla

We consider a discrete Schroedinger operator whose potential is the sum of a Wigner-von Neumann term and a summable term. The essential spectrum of this operator equals to the interval [-2,2]. Inside this interval, there are two critical…

Spectral Theory · Mathematics 2012-03-12 Sergey Simonov

We consider the difference $f(H_1)-f(H_0)$, where $H_0=-\Delta$ and $H_1=-\Delta+V$ are the free and the perturbed Schr\"odinger operators in $L^2(\mathbb R^d)$, and $V$ is a real-valued short range potential. We give a sharp sufficient…

Spectral Theory · Mathematics 2019-07-08 Rupert L. Frank , Alexander Pushnitski

We provide a sufficient condition for a linear differential operator with constant coefficients $P(D)$ to be surjective on $C^\infty(X)$ and $\mathscr{D}'(X)$, respectively, where $X\subseteq\mathbb{R}^d$ is open. Moreover, for certain…

Analysis of PDEs · Mathematics 2019-03-27 Thomas Kalmes

We give a necessary and sufficient condition for an inverse sequence $S_0 \leftarrow S_1 \leftarrow \dots$ indexed by natural numbers to have ${\rm lim}^1S=0$. This condition can be treated as a transfinite version of the Mittag-Leffler…

K-Theory and Homology · Mathematics 2024-09-11 Mishel Carelli , Sergei O. Ivanov

The extended W-algebra of type sl_2 at positive rational level, denoted by M_{p_+,p_-}, is a vertex operator algebra that was originally proposed in [1]. This vertex operator algebra is an extension of the minimal model vertex operator…

Quantum Algebra · Mathematics 2014-07-16 Akihiro Tsuchiya , Simon Wood

We initiate and study the theory of ``real decomposable maps" between real operator systems. Formally, this is new even in the complex case, which hitherto has restricted itself to the case where the systems are complex C*-algebras. We…

Operator Algebras · Mathematics 2026-05-11 David P. Blecher , Christiaan H. Pretorius

In this paper we introduce a new dynamical condition, the comb geometric control condition, which is sufficient for observability of the Schr\"odinger equation in Euclidean space. We provide examples which show this condition is strictly…

Analysis of PDEs · Mathematics 2026-04-14 Walton Green , Perry Kleinhenz

We show a Condition Number Theorem for the condition number of zero counting for real polynomial systems. That is, we show that this condition number equals the inverse of the normalized distance to the set of ill-posed systems (i.e., those…

Numerical Analysis · Computer Science 2010-07-12 Felipe Cucker , Teresa Krick , Gregorio Malajovich , Mario Wschebor

It is well known that for irreducible, square-integrable representations of a locally compact group, there exist so-called admissible vectors which allow the construction of generalized continuous wavelet transforms. In this paper we…

Functional Analysis · Mathematics 2016-09-07 Hartmut Fuehr

We give necessary and sufficient conditions for a bounded operator defined between complex Hilbert spaces to be absolutely norm attaining. We discuss structure of such operators in the case of self-adjoint and normal operators separately.…

Spectral Theory · Mathematics 2018-01-09 G. Ramesh , D. Venku Naidu

We provide a class of necessary and sufficient conditions for the discreteness of spectrum of Schr\"odinger operators with scalar potentials which are semibounded below. The classical discreteness of spectrum criterion by A.M.Molchanov…

Spectral Theory · Mathematics 2007-05-23 Vladimir Maz'ya , Mikhail Shubin

Several methods for checking admissibility of rules in the modal logic $S4$ are presented in [1], [15]. These methods determine admissibility of rules in $S4$, but they don't determine or give substitutions rejecting inadmissible rules. In…

Logic · Mathematics 2017-01-25 Mojtaba Aghaei , Maryam Rostami Giv

A normalized positive operator measure $X\mapsto E(X)$ has the norm-1-property if $\no{E(X)}=1$ whenever $E(X)\ne O$. This property reflects the fact that the measurement outcome probabilities for the values of such observables can be made…

Quantum Physics · Physics 2009-11-07 T. Heinonen , P. Lahti , J. -P. Pellonpaa , S. Pulmannova , K. Ylinen

The purpose of this paper is two-fold: firstly, we give a characterization on the level of non-unital operator systems for when the zero map is a boundary representation. As a consequence, we show that a non-unital operator system arising…

Operator Algebras · Mathematics 2024-08-13 Se-Jin Kim

Confident prediction is highly relevant in machine learning; for example, in applications such as medical diagnoses, wrong prediction can be fatal. For classification, there already exist procedures that allow to not classify data when the…

Statistics Theory · Mathematics 2015-07-28 Christophe Denis , Mohamed Hebiri

We consider the Schr{\"o}dinger equation in $\mathbf{R}^d$, $d \ge 1$, with a confining potential growing at most quadratically. Our main theorem characterizes open sets from which observability holds, provided they are sufficiently regular…

Analysis of PDEs · Mathematics 2025-05-14 Antoine Prouff
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