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We consider the analytic continuation of the transfer function for a 2x2 matrix Hamiltonian into the unphysical sheets of the energy Riemann surface. We construct non-selfadjoint operators representing operator roots of the transfer…

Mathematical Physics · Physics 2007-05-23 A. K. Motovilov , R. Mennicken

We present a new and simple approach to the theory of multiple operator integrals that applies to unbounded operators affiliated with general von Neumann algebras. For semifinite von Neumann algebras we give applications to the Fr\'echet…

Operator Algebras · Mathematics 2007-05-23 N. A. Azamov , A. L. Carey , P. G. Dodds , F. A. Sukochev

The notion of translation (shift) is straightforward in classical signal processing, however, it is challenging on an irregular graph structure. In this work, we present an approach to characterize the translation operator in various signal…

Signal Processing · Electrical Eng. & Systems 2020-01-22 Amin Jalili , Sadid Sahami , Chong-Yung Chi

The aim of this paper is to study some properties of left translates of a square integrable function on the Heisenberg group. First, a necessary and sufficient condition for the existence of the canonical dual to a function $\varphi\in…

Functional Analysis · Mathematics 2017-12-04 R. Radha , Saswata Adhikari

Frames in separable Hilbert spaces gives stable analysis and reconstruction of each vector in the underlying space. In this paper, we study frame conditions for a collection of matrix-valued functions obtained by non-uniform shifts. We give…

Functional Analysis · Mathematics 2025-08-04 Hari Krishan Malhotra , Manisha Chhillar , Lalit Kumar Vashisht

We define a class of discrete operators acting on infinite, finite or periodic sequences mimicking the standard properties of pseudo-differential operators. In particular we can define the notion of order and regularity, and we recover the…

Analysis of PDEs · Mathematics 2021-10-01 Erwan Faou , Benoît Grébert

The high-order numerical analysis for fractional Laplacian via the Riesz fractional derivative, under the low regularity solution, has presented significant challenges in the past decades. To fill in this gap, we design a grid mapping…

Numerical Analysis · Mathematics 2025-02-18 Minghua Chen , Jianxing Han , Jiankang Shi , Fan Yu

We establish that the spectral multiplier $\frak{M}(G_{\alpha})$ associated to the differential operator $$ G_{\alpha}=- \Delta_x +\sum_{j=1}^m{{\alpha_j^2-1/4}\over{x_j^2}}-|x|^2 \Delta_y \; \text{on} (0,\infty)^m \times \R^n,$$ which we…

Classical Analysis and ODEs · Mathematics 2023-10-25 Víctor Almeida , Jorge J. Betancor , Alejandro J. Castro , Kishin Sadarangani

In this paper, let $L=L_{0}+V$ be a Schr\"{o}dinger type operator where $L_{0}$ is higher order elliptic operator with complex coefficients in divergence form and $V$ is signed measurable function, under the strongly subcritical assumption…

Classical Analysis and ODEs · Mathematics 2016-03-29 Qingquan Deng , Yong Ding , Xiaohua Yao

In this paper our aim is to find the radii of $\gamma$-Spirallike of order $\alpha$ and convex $\gamma$-Spirallike of order $\alpha$ for three different kinds of normalizations of the function…

Complex Variables · Mathematics 2022-11-24 Sercan Kazımoğlu , Kamaljeet Gangania

In this article, we impose a new class of fractional analytic functions in the open unit disk. By considering this class, we define a fractional operator, which is generalized Salagean and Ruscheweyh differential operators. Moreover, by…

Complex Variables · Mathematics 2016-02-26 Zainab E. Abdulnaby , Rabha W. Ibrahim , Adem Kilicman

We prove sharp power-weighted $L^p$, weak type and restricted weak type inequalities for the heat semigroup maximal operator and Riesz transforms associated with the Bessel operator $B_{\nu}$ in the exotic range of the parameter $-\infty <…

Classical Analysis and ODEs · Mathematics 2022-09-09 Bartosz Langowski , Adam Nowak

We provide conditions for exact reconstruction of a bandlimited function from irregular polar samples of its Radon transform. First, we prove that the Radon transform is a continuous L2-operator for certain classes of bandlimited signals.…

Numerical Analysis · Mathematics 2013-07-05 Thomas Wiese , Laurent Demaret

In this work, we extend Wigner's original framework to analyze linear operators by examining the relationship between their Wigner and Schwartz kernels. Our approach includes the introduction of (quasi-)algebras of Fourier integral…

Analysis of PDEs · Mathematics 2024-06-18 Elena Cordero , Gianluca Giacchi , Edoardo Pucci

Regarding quaternions as normal matrices, we first characterize the $2\times 2$ matrix-valued functions, defined on subsets of quaternions, whose values are quaternions. Then we investigate the regularity of quaternionic-valued functions,…

Functional Analysis · Mathematics 2019-02-12 Florian-Horia Vasilescu

Assume that $\nu$ is a positive integer and $\delta=0, 1$ or $2$. In this paper we introduce the orthogonal graph $\Gamma^{2\nu+\delta}$ over a Galois ring of odd characteristic and prove that it is arc transitive. Moreover, we compute its…

Combinatorics · Mathematics 2013-08-20 Fenggao Li , Jun Guo , Kaishun Wang

In this paper we introduce a new family of operator-valued distributions on Euclidian space acting by convolution on differential forms. It provides a natural generalization of the important Riesz distributions acting on functions, where…

Differential Geometry · Mathematics 2017-02-06 Fischmann Matthias , Ørsted Bent

We extend the classical Bernstein inequality to a general setting including Schr{\"o}dinger operators and divergence form elliptic operators on Riemannian manifolds or domains. Moreover , we prove a new reverse inequality that can be seen…

Analysis of PDEs · Mathematics 2021-06-11 Rafik Imekraz , El Maati Ouhabaz

Let $S\subset\R^d$ be a bounded subset with positive Lebesgue measure. The Paley-Wiener space associated to $S$, $PW_S$, is defined to be the set of all square-integrable functions on $\R^d$ whose Fourier transforms vanish outside $S$. A…

Classical Analysis and ODEs · Mathematics 2010-01-25 A. Bailey , Th. Schlumprecht , N. Sivakumar

The classical theorems of Mittag-Leffler and Weierstrass show that when $\{\lambda_n\}$ is a sequence of distinct points in the open unit disk $\D$, with no accumulation points in $\D$, and $\{w_n\}$ is any sequence of complex numbers,…

Complex Variables · Mathematics 2020-10-09 Javad Mashreghi , Marek Ptak , William T. Ross