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We investigate the spectrum of differentiation matrices for certain operators on the sphere that are generated from collocation at a set of scattered points $X$ with positive definite and conditionally positive definite kernels. We focus on…

Numerical Analysis · Mathematics 2023-12-27 Thomas Hangelbroek , Christian Rieger , Grady Wright

In the first section we provide a solution to the M. G. Krein problem about an inner description of the space $L_2(\Sigma,H).$ In the second section we introduce the multiplicity function for an operator measure. Making use of the…

Spectral Theory · Mathematics 2007-05-23 Mark M. Malamud , Semen M. Malamud

Neural operators on irregular meshes face a fundamental tension. Spectral positional encodings, the natural choice for capturing geometry, require cubic-complexity eigendecomposition and inadvertently break gauge invariance through…

Machine Learning · Computer Science 2026-05-13 Mattia Rigotti , Nicholas Thumiger , Thomas Frick

Given N quantum systems prepared according to the same density operator \rho, we propose a measurement on the N-fold system which approximately yields the spectrum of \rho. The projections of the proposed observable decompose the Hilbert…

Quantum Physics · Physics 2009-11-07 M. Keyl , R. F. Werner

Much recent work has addressed the solution of a family of partial differential equations by computing the inverse operator map between the input and solution space. Toward this end, we incorporate function-valued reproducing kernel Hilbert…

Numerical Analysis · Mathematics 2022-04-05 Kaijun Bao , Xu Qian , Ziyuan Liu , Songhe Song

It is known that convergence of l.s.b. closed symmetric sesquilinear forms implies norm resolvent convergence of the associated self-adjoint operators and this in turn convergence of discrete spectra. In this paper in both cases sharp…

Mathematical Physics · Physics 2017-12-12 Johannes F. Brasche , Robert Fulsche

In this article, we first introduce a singular fractional Sturm-Liouville eigen-problems (SFSLP) on unbounded domain. The associated fractional differential operators in these problems are both Weyl and Caputo type . The properties of…

Numerical Analysis · Mathematics 2015-02-20 T. Aboelenen , H. M. El-Hawary

The graph Hilbert transform (GHT) is a key tool in constructing analytic signals and extracting envelope and phase information in graph signal processing. However, its utility is limited by confinement to the graph Fourier domain, a fixed…

Signal Processing · Electrical Eng. & Systems 2025-09-23 Daxiang Li , Zhichao Zhang

This paper deals with the generalized spectrum of continuously invertible linear operators defined on infinite dimensional Hilbert spaces. More precisely, we consider two bounded, coercive, and self-adjoint operators $\bc{A, B}: V\mapsto…

Numerical Analysis · Mathematics 2021-03-02 Tomáš Gergelits , Bjørn Fredrik Nielsen , Zdeněk Strakoš

This paper studies the construction of a refinement kernel for a given operator-valued reproducing kernel such that the vector-valued reproducing kernel Hilbert space of the refinement kernel contains that of the given one as a subspace.…

Machine Learning · Computer Science 2011-02-08 Yuesheng Xu , Haizhang Zhang , Qinghui Zhang

In this paper, we investigate the spectrum of the self adjoint differential operator with operator coefficitent in a separable Hilbert space. We also derive asymptotic formulas for the sum of eigenvalues of this operator.

Spectral Theory · Mathematics 2019-09-10 Yonca Sezer , Özlem Bakşi

This paper is centred on the spectral study of a Random Fourier matrix, that is an $n\times n$ matrix $A$ whose $(j, k)$ entries are $\exp(2i\pi m X_jY_k)$, with $X_j$ and $Y_k$ two i.i.d sequences of random variables and $1\leq m\leq n$ is…

Classical Analysis and ODEs · Mathematics 2019-04-16 Aline Bonami , Abderrazek Karoui

This work develops a functional-analytic framework based on the transfinite iteration of a self-adjoint operator. Beginning with a densely defined self-adjoint operator $A$ on a Hilbert space $H$, a spectral-transform functor $\Phi$ is…

Functional Analysis · Mathematics 2025-08-08 Faruk Alpay , Hamdi Alakkad , Taylan Alpay

We provide square-root n consistency results regarding estimation of the spectral representation of covariance operators of Hilbertian time series, in a setting with imperfect measurements. This is a generalization of the method developed…

Statistics Theory · Mathematics 2016-04-12 Eduardo Horta , Flavio Ziegelmann

Starting from a general operator representation in the time-frequency domain, this paper addresses the problem of approximating linear operators by operators that are diagonal or band-diagonal with respect to Gabor frames. A…

Analysis of PDEs · Mathematics 2008-09-17 Monika Dorfler , Bruno Torresani

Spectral clustering is popular among practitioners and theoreticians alike. While performance guarantees for spectral clustering are well understood, recent studies have focused on enforcing ``fairness'' in clusters, requiring them to be…

Machine Learning · Computer Science 2022-09-27 Shubham Gupta , Ambedkar Dukkipati

Spectral inclusion and spectral pollution results are proved for sequences of linear operators of the form $T_0 + i \gamma s_n$ on a Hilbert space, where $s_n$ is strongly convergent to the identity operator and $\gamma > 0$. We work in…

Spectral Theory · Mathematics 2021-01-06 Alexei Stepanenko

We study functions whose time-frequency content are concentrated in a compact region in phase space using time-frequency localization operators as a main tool. We obtain approximation inequalities for such functions using a finite linear…

Functional Analysis · Mathematics 2016-12-28 Monika Dörfler , Gino Angelo Velasco

In modeling quantum systems or wave phenomena, one is often interested in identifying eigenstates that approximately carry a specified property; scattering states approximately align with incoming and outgoing traveling waves, for instance,…

Numerical Analysis · Mathematics 2024-08-13 David Darrow , Jeffrey S. Ovall

The paper considers the general form of self-adjoint boundary value problems for momentum operators with nonlocal potentials. We give an analysis of the eigenvalue distribution as zeros of the characteristic functions, for which their…

Functional Analysis · Mathematics 2025-12-15 Kamila Dębowska , Irina L. Nizhnik