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Actions of locally compact groups and quantum groups on W*-ternary rings of operators are discussed and related crossed products introduced. The results generalise those for von Neumann algebraic actions with proofs based mostly on passing…

Operator Algebras · Mathematics 2017-10-18 Pekka Salmi , Adam Skalski

This paper compares two generalizations of Heisenberg groups and studies their connection to one of the major open problems in the field of locally compact abelian groups, namely the description of the self-dual locally compact abelian…

Group Theory · Mathematics 2017-09-11 Marco Bonatto , Dikran Dikranjan

The purpose of this paper is to generalize a very famous result on products of normal operators, due to I. Kaplansky. The context of generalization is that of bounded hyponormal and unbounded normal operators on complex separable Hilbert…

Functional Analysis · Mathematics 2014-03-04 Abdelkader Benali , Mohammed Hichem Mortad

We prove that the image of an elliptic operator on a smooth separable Hilbert fibre bundle on compact manifolds is closed with respect to the natural pre-Hilbert topology. We consider a tensor product of the operator, which is invariant…

Differential Geometry · Mathematics 2022-08-24 Svatopluk Krýsl

We consider several differential operators on compact almost-complex, almost-Hermitian and almost-K\"ahler manifolds. We discuss Hodge Theory for these operators and a possible cohomological interpretation. We compare the associated spaces…

Differential Geometry · Mathematics 2020-03-09 Nicoletta Tardini , Adriano Tomassini

In this paper we study some basic properties of bicomplex linear operators on bicomplex Hilbert spaces. Further we discuss some applications of Hahn-Banach theorem on bicomplex Banach modules. We also introduce and discuss some bicomplex…

Functional Analysis · Mathematics 2014-06-02 Romesh Kumar , Kulbir Singh

We introduce and investigate using Hilbert modules the properties of the Fourier algebra A(G) for a locally compact groupoid G. We establish a duality theorem for such groupoids in terms of multiplicative module maps. This includes as a…

Operator Algebras · Mathematics 2007-05-23 Alan L. T. Paterson

We prove that if there are $\mathfrak c$ incomparable selective ultrafilters then, for every infinite cardinal $\kappa$ such that $\kappa^\omega=\kappa$, there exists a group topology on the free Abelian group of cardinality $\kappa$…

Logic · Mathematics 2021-03-25 M. K. Bellini , K. P. Hart , V. O. Rodrigues , A. H. Tomita

Let $G$ be a locally compact abelian group with a Haar measure, and $Y$ be a measure space. Suppose that $H$ is a reproducing kernel Hilbert space of functions on $G\times Y$, such that $H$ is naturally embedded into $L^2(G\times Y)$ and is…

Functional Analysis · Mathematics 2025-04-28 Crispin Herrera-Yañez , Egor A. Maximenko , Gerardo Ramos-Vazquez

We consider continuous extensions of minimal rotations on a locally connected compact group X by arbitrary locally compact Lie groups and prove regularity (i.e. the existence of orbit closures which project onto the whole basis X) in…

Dynamical Systems · Mathematics 2008-04-17 Ulrich Haboeck , Vyacheslav Kulagin

We present a new systematic method to construct Abelian functions on Jacobian varieties of plane, algebraic curves. The main tool used is a symmetric generalisation of the bilinear operator defined in the work of Baker and Hirota. We give…

Mathematical Physics · Physics 2012-06-27 Matthew England , Chris Athorne

We consider several harmonic analysis operators in the multi-dimensional context of the Dunkl Laplacian with the underlying group of reflections isomorphic to $\mathbb{Z}_2^n$ (also negative values of the multiplicity function are…

Classical Analysis and ODEs · Mathematics 2023-10-25 Alejandro J. Castro , Tomasz Z. Szarek

In this paper, we consider Abelian varieties over function fields that arise as twists of Abelian varieties by cyclic covers of irreducible quasi-projective varieties. Then, in terms of Prym varieties associated to the cyclic covers, we…

Number Theory · Mathematics 2018-01-26 Sajad Salami

We present forms of the classical Riesz-Kolmogorov theorem for compactness that are applicable in a wide variety of settings. In particular, our theorems apply to classify the precompact subsets of the Lebesgue space $L^2$, Paley-Wiener…

Complex Variables · Mathematics 2023-10-18 Mishko Mitkovski , Cody B. Stockdale , Nathan A. Wagner , Brett D. Wick

We construct an Abel-Jacobi type map on the homologically trivial part of Lawson homology groups. It generalizes the Abel-Jacobi map constructed by Griffiths. By using a result of H. Clemens, we give some examples of smooth projective…

Algebraic Geometry · Mathematics 2007-05-23 Wenchuan Hu

An ergodic action of a compact quantum group G on an operator algebra A can be interpreted as a quantum homogeneous space for G. Such an action gives rise to the category of finite equivariant Hilbert modules over A, which has a module…

Operator Algebras · Mathematics 2019-01-29 Kenny De Commer , Makoto Yamashita

We show that there exist non-compact composition operators in the connected component of the compact ones on the classical Hardy space $H^2$ on the unit disc. This answers a question posed by Shapiro and Sundberg in 1990. We also establish…

Functional Analysis · Mathematics 2007-06-20 Eva A. Gallardo-Gutiérrez , Maria J. González , Pekka Nieminen , Eero Saksman

We show that for any compact connected group G the second cohomology group defined by unitary invariant 2-cocycles on \hat G is canonically isomorphic to H^2(\hat{Z(G)};T). This implies that the group of autoequivalences of the C*-tensor…

Operator Algebras · Mathematics 2011-05-17 Sergey Neshveyev , Lars Tuset

In this paper, we study the product of a Hankel operator and a Toeplitz operator on the Hardy space. We give necessary and sufficient conditions of when such a product $H_f T_g$ is compact.

Functional Analysis · Mathematics 2014-03-11 Cheng Chu

Let a compact group G act on real or complex C*-algebras A and B, with A separable and B sigma-unital. We express the G-equivariant Kasparov groups KK_n(A,B) by algebraic K-groups of a certain additive category.

K-Theory and Homology · Mathematics 2007-05-23 Tamaz Kandelaki