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This paper focuses on different reductions of 2-dimensional (2d-)Toda hierarchy. Symmetric and skew symmetric moment matrices are firstly considered, resulting in the differential relations between symmetric/skew symmetric tau functions and…

Exactly Solvable and Integrable Systems · Physics 2020-01-07 Shi-Hao Li , Guo-Fu Yu

This paper introduces and investigates the class of \textit{$k$-quasi $n$-power posinormal operators} in Hilbert spaces, generalizing both posinormal and $n$-power posinormal operators. We establish fundamental properties including matrix…

Functional Analysis · Mathematics 2025-09-18 Sophiya S Dharan , T. Prasad , M. H. M. Rashid

This paper is about the orbifold theory for vertex operator superalgebras. Given a vertex operator superalgebra V and a finite automorphism group G of V, we show that the trace functions associated to the twisted sectors are holomorphic in…

Quantum Algebra · Mathematics 2009-11-10 Chongying Dong , Zhongping Zhao

The Hurwitz space is the moduli space of pairs $(X,f)$ where $X$ is a compact Riemann surface and $f$ is a meromorphic function on $X$. We study the Laplace operator $\Delta^{|df|^2}$ of the flat singular Riemannian manifold $(X,|df|^2)$.…

Spectral Theory · Mathematics 2014-10-14 Luc Hillairet , Victor Kalvin , Alexey Kokotov

Let $\Delta$ be a closed, cocompact subgroup of $G \times \widehat{G}$, where $G$ is a second countable, locally compact abelian group. Using localization of Hilbert $C^*$-modules, we show that the Heisenberg module…

Operator Algebras · Mathematics 2022-07-12 Are Austad , Ulrik Enstad

First, we study the subskewfield of rational pseudodifferential operators over a differential field K generated in the skewfield of pseudodifferential operators over K by the subalgebra of all differential operators. Second, we show that…

Rings and Algebras · Mathematics 2015-12-18 Sylvain Carpentier , Alberto De Sole , Victor G. Kac

Let $\mathcal{D}$ be the class of radial weights on the unit disk which satisfy both forward and reverse doubling conditions. Let $g$ be an analytic function on the unit disk $\mathbb{D}$. We characterize bounded and compact Volterra type…

Functional Analysis · Mathematics 2021-07-06 Yongjiang Duan , Siyu Wang , Zipeng Wang

Let $\{\alpha_n\}_{n\geq 0}$ be a sequence of scalars in the open unit disc of $\mathbb{C}$, and let $\{l_n\}_{n\geq 0}$ be a sequence of natural numbers satisfying $\sum_{n=0}^\infty (1 - l_n|\alpha_n|) <\infty$. Then the joint $(M_{z_1},…

Functional Analysis · Mathematics 2014-10-24 B. K. Das , Jaydeb Sarkar

This paper discusses the two classical Hardy operators $\mathcal{H}_{1}$ on $L^2(0, 1)$ and $\mathcal{H}_{\infty}$ on $L^2(0, \infty)$ initially studied by Brown, Halmos and Shields. Particular emphasis is given to the construction of…

Functional Analysis · Mathematics 2025-01-27 Eva A. Gallardo-Guttierrez , Jonathan R. Partington , William T. Ross

We extend the matrix representation of magnetic pseudo-differential operators in a tight Gabor frame from [arXiv:1804.05220, arXiv:2212.12229] to asymmetrical quantizations and smooth symbols dominated by a tempered weight (and not just…

Mathematical Physics · Physics 2026-02-18 Mikkel Hviid Thorn

We construct a new family of mod $p$ weight shifting differential operators on Hodge type Shimura varieties at hyperspecial level. First we construct basic theta operators, labelled by positive roots, that generalize Katz's theta operator…

Number Theory · Mathematics 2026-01-19 Martin Ortiz

We introduce and study the Hilbert space of $(L^2,\Gamma,\chi)$-likewise theta functions on $\mathbb{R}^d$ with respect to a given discrete subgroup $\Gamma$ of arbitrary rank and a character $\chi$ of $\Gamma$. A concrete description is…

Complex Variables · Mathematics 2017-02-06 A. Ghanmi , A. Intissar , Z. Mouhcine , M. Ziyat

Let $\Omega$ be either the unit polydisc $\mathbb D^d$ or the unit ball $\mathbb B_d$ in $\mathbb C^d$ and $G$ be a finite pseudoreflection group which acts on $\Omega.$ Associated to each one-dimensional representation $\varrho$ of $G,$ we…

Complex Variables · Mathematics 2022-05-03 Gargi Ghosh

The spectral decomposition for an explicit second-order differential operator $T$ is determined. The spectrum consists of a continuous part with multiplicity two, a continuous part with multiplicity one, and a finite discrete part with…

Classical Analysis and ODEs · Mathematics 2014-05-23 Wolter Groenevelt , Erik Koelink

We give a complete characterization of the sequences $\beta = (\beta_n)$ of positive numbers for which all composition operators on $H^2 (\beta)$ are bounded, where $H^2 (\beta)$ is the space of analytic functions $f$ on the unit disk…

Complex Variables · Mathematics 2023-12-07 Pascal Lefèvre , Daniel Li , Hervé Queffélec , Luis Rodríguez-Piazza

The goal of the present paper is to push Sz.-Nagy--Foias model theory for a completely nonunitary Hilbert-space contraction operator $T$, to the case of a commuting pair of contraction operators $(T_1, T_2)$ having product $T = T_1 T_2$…

Functional Analysis · Mathematics 2018-10-01 Joseph A. Ball , Haripada Sau

The image of a given orthonormal basis for a separable Hilbert space $\mathcal{H}$ under a bijective, bounded, and linear operator acting on $\mathcal{H}$ is called a Riesz basis of $\mathcal{H}$. Contrary to what happens with Riesz bases…

Functional Analysis · Mathematics 2026-01-27 Jyoti , Lalit Kumar Vashisht

We investigate the Hardy space H^1_L associated to the Schr\"odinger operator L=-\Delta+V on R^n, where V=\sum_{j=1}^d V_j. We assume that each V_j depends on variables from a linear subspace VV_j of \Rn, dim VV_j \geq 3, and V_j belongs to…

Functional Analysis · Mathematics 2011-09-27 Jacek Dziubański , Marcin Preisner

We study a class of representations of the Cuntz algebras O_N, N=2,3,..., acting on L^2(T) where T=R/2\pi Z. The representations arise in wavelet theory, but are of independent interest. We find and describe the decomposition into…

funct-an · Mathematics 2008-02-03 Ola Bratteli , Palle E. T. Jorgensen

In this paper, we give necessary and sufficient conditions for weighted $L^2$ estimates with matrix-valued measures of well localized operators. Namely, we seek estimates of the form: \[ \| T(\mathbf{W} f)\|_{L^2(\mathbf{V})} \le…

Functional Analysis · Mathematics 2016-11-22 Kelly Bickel , Amalia Culiuc , Sergei Treil , Brett D. Wick