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Let W be a Weyl group. We can define the notion of positivity of a W-module in terms of the corresponding module over the asymptotic Iwahori-Hecke algebra. We state a conjecture which says that certain explicit W-modules are positive and we…

Representation Theory · Mathematics 2026-01-19 G. Lusztig

We study the frame properties of the Gabor systems $$\mathfrak{G}(g;\alpha,\beta):=\{e^{2\pi i \beta m x}g(x-\alpha n)\}_{m,n\in\mathbb{Z}}.$$ In particular, we prove that for Herglotz windows $g$ such systems always form a frame for…

Functional Analysis · Mathematics 2021-03-17 Yurii Belov , Aleksei Kulikov , Yurii Lyubarskii

We introduce a new version $kk^{\rm alg}$ of bivariant $K$-theory that is defined on the category of all locally convex algebras. A motivating example is the Weyl algebra $W$, i.e. the algebra generated by two elements satisfying the…

K-Theory and Homology · Mathematics 2007-05-23 Joachim Cuntz

Let $\hil$ be a finite dimensional (real or complex) Hilbert space and let $\{a_i\}_{i=1}^\infty$ be a non-increasing sequence of positive numbers. Given a finite sequence of vectors $\f$ in $\hil$ we find necessary and sufficient…

Functional Analysis · Mathematics 2016-09-07 P. Massey , M. Ruiz

Let G be a locally compact non-compact group. We show that under a very mild assumption on the weight function w, the weighted group algebra L_1(G,w) is strongly Arens irregular in the sense of Dales-Lamb-Lau. To this end, we first derive a…

Functional Analysis · Mathematics 2007-05-23 Matthias Neufang

We consider dual frames generated by actions of countable discrete groups on a Hilbert space. Module frames in a class of modules over a group algebra are shown to coincide with a class of ordinary frames in a representation of the group.…

Functional Analysis · Mathematics 2009-11-24 Kjetil Roysland

We discuss the tight-binding models of solid state physics with the $Z_2$ sublattice symmetry in the presence of elastic deformations, and their important particular case -the tight binding model of graphene. In order to describe the…

Mesoscale and Nanoscale Physics · Physics 2019-08-13 I. V. Fialkovsky , M. A. Zubkov

Motivated by the study of Weyl structures on conformal manifolds admitting parallel weightless forms, we define the notion of conformal product of conformal structures and study its basic properties. We obtain a classification of Weyl…

Differential Geometry · Mathematics 2019-01-08 Florin Belgun , Andrei Moroianu

In this paper, we construct a large class of new simple modules over the twisted $N=2$ superconformal algebra. These new simple modules are restricted modules based on the simple modules over certain finite-dimensional solvable Lie…

Representation Theory · Mathematics 2025-06-05 Haibo Chen , Yucai Su , Yukun Xiao

We develop the bivector formalism in higher dimensional Lorentzian spacetimes. We define the Weyl bivector operator in a manner consistent with its boost-weight decomposition. We then algebraically classify the Weyl tensor, which gives rise…

General Relativity and Quantum Cosmology · Physics 2010-01-06 A Coley , S Hervik

In this paper, we consider some non-weight modules over the Lie algebra of Weyl type. First, we determine the modules whose restriction to $U(\frak h)$ are free of rank $1$ over the Lie algebra of differential operators on the circle. Then…

Representation Theory · Mathematics 2022-12-06 Munayim Dilxat , Shoulan Gao , Dong Liu , Limeng Xia

Wavelet and Gabor systems are based on translation-and-dilation and translation-and-modulation operators, respectively. They have been extensively studied. However, dilation-and-modulation systems have not, and they cannot be derived from…

Functional Analysis · Mathematics 2017-08-22 Yun-Zhang Li , Wei Zhang

We derive easily verifiable conditions which characterize when complex Seidel matrices containing cube roots of unity have exactly two eigenvalues. The existence of such matrices is equivalent to the existence of equiangular tight frames…

Functional Analysis · Mathematics 2008-09-01 Bernhard G. Bodmann , Vern I. Paulsen , Mark Tomforde

Let $V$ be a simple vertex operator algebra containing a rank $n$ Heisenberg vertex algebra $H$ and let $C=\text{Com}\left( {H}, {V}\right)$ be the coset of ${H}$ in ${V}$. Assuming that the representation categories of interest are vertex…

Quantum Algebra · Mathematics 2020-05-13 Thomas Creutzig , Shashank Kanade , Andrew R. Linshaw , David Ridout

We discuss several seemingly assorted objects: the umbral calculus, generalised translations and associated transmutations, symbolic calculus of operators. The common framework for them is representations of the Weyl algebra of the…

Analysis of PDEs · Mathematics 2023-12-01 Vladimir V. Kisil

We discuss some specializations of the frames of flat orthonormal frame bundles over geometries of indefinite signature, and the resulting symmetries of families of embedded Riemannian or pseudo-Riemannian geometries. The specializations…

General Relativity and Quantum Cosmology · Physics 2013-02-18 Frank B. Estabrook

The Grothendieck groups of the categories of finitely generated modules and finitely generated projective modules over a tower of algebras can be endowed with (co)algebra structures that, in many cases of interest, give rise to a dual pair…

Representation Theory · Mathematics 2014-10-24 Alistair Savage , Oded Yacobi

We address two problems regarding the structure and representation theory of finite W-algebras associated with the general linear Lie algebras. Finite W-algebras can be defined either via the Whittaker model of Kostant or, equivalently, by…

Rings and Algebras · Mathematics 2009-06-06 Vyacheslav Futorny , Alexander Molev , Serge Ovsienko

Let $ L((T^{-1}))$ be the space of (inverse) Laurent serieswith coefficients in some field $L$. It has a standard degree map and the induced topology. With its usual addition and a new product on this space which is continuous and preserves…

Rings and Algebras · Mathematics 2024-01-31 Gang Han , Yulin Chen , Zhennan Pan

We introduce a new family of twisted generalized Weyl algebras, called multiparameter twisted Weyl algebras, for which we parametrize all simple quotients of a certain kind. Both Jordan's simple localization of the multiparameter quantized…

Quantum Algebra · Mathematics 2012-10-26 Vyacheslav Futorny , Jonas T. Hartwig