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We revisit the notion of flatness for semimodules over semirings. In particular, we introduce and study a new notion of uniformly flat semimodules based on the exactness of the tensor functor. We also investigate the relations between this…

Rings and Algebras · Mathematics 2012-01-04 Jawad Abuhlail

To improve the numerical efficiency of iterative algorithms for inverting the frame operator, the controlled frame was introduced by Balazs et al. \cite{Balazs}, and has since been given more importance. In this paper, we introduce the…

Functional Analysis · Mathematics 2019-04-15 N. K. Sahu

Composition operators with analytic symbols on some reproducing kernel Hilbert spaces of entire functions on a complex Hilbert space are studied. The questions of their boundedness, seminormality and positivity are investigated. It is…

Functional Analysis · Mathematics 2016-10-17 Jan Stochel , Jerzy B. Stochel

In this paper, we characterize hypercyclic generalized bilateral weighted shift operators on the standard Hilbert module over the C*-algebra of compact operators on the separable Hilbert space. Moreover, we give necessary and sufficient…

Operator Algebras · Mathematics 2024-01-17 Stefan Ivkovic

A module M over a vertex algebra V is half-integrable if a_n act locally nilpotently on M for all a in V, m in M, n>0. We study half-integrable modules over sheaves of twisted chiral differential operators (TCDO) on a smooth variety X. We…

Representation Theory · Mathematics 2010-10-20 Dmytro Chebotarov

Semi-invertible multiplicative ergodic theorems establish the existence of an Oseledets splitting for cocycles of non-invertible linear operators (such as transfer operators) over an invertible base. Using a constructive approach, we…

Dynamical Systems · Mathematics 2012-11-26 Cecilia González-Tokman , Anthony Quas

Motivated by two norm equations used to characterize the Friedrichs angle, this paper studies $C^*$-isomorphisms associated with two projections by introducing the matched triple and the semi-harmonious pair of projections. A triple…

Operator Algebras · Mathematics 2022-03-03 Chunhong Fu , Qingxiang Xu , Guanjie Yan

This paper considers universal Hilbert space operators in the sense of Rota, and gives criteria for universality of semigroups in the context of uniformly continuous semigroups and contraction semigroups. Specific examples are given.…

Functional Analysis · Mathematics 2018-05-09 B. Célariès , I. Chalendar , J. R. Partington

We extend the spectral theory of commutative C*-categories to the non full-case, introducing a suitable notion of spectral spaceoid provinding a duality between a category of "non-trivial" *-functors of non-full commutative C*-categories…

Operator Algebras · Mathematics 2025-11-04 Paolo Bertozzini , Roberto Conti , Wicharn Lewkeeratiyutkul , Kasemsun Rutamorn

In this paper, we study three types of Birkhoff-James orthogonality in Hilbert $C^*$-modules, that is, the strong, quasi-strong, and original Birkhoff-James orthogonality. In general, the strong Birkhoff-James orthogonality is stronger than…

Functional Analysis · Mathematics 2025-11-20 Soumitra Daptari , Koki Igarashi , Jumpei Nakamura , Ryotaro Tanaka

This study aims at combining the concepts of $g$-frame and $K$-frame for a Hilbert $C^*$-module $U$, for an operator $K \in End^*_A(U)$, where $End^*_A(U)$ contains all adjointable $A$-linear maps on $U$. As a result, continuous…

Functional Analysis · Mathematics 2024-10-07 Jahangir Cheshmavar , Javad Baradaran , Asadollah Hossienpour

Apart from presenting some new insights and results, one of our main purposes is to put some records in the development of von Neumann modules straight. The von Neumann or $W^*$-objects among the Hilbert ($C^*$-)modules are around since the…

Operator Algebras · Mathematics 2023-01-26 Michael Skeide

Grayson, developing ideas of Quillen, has made computations of the K-theory of "semi-linear endomorphisms". In the present text we develop a technique to compute these groups in the case of Frobenius semi-linear actions. The main idea is to…

K-Theory and Homology · Mathematics 2016-10-13 Oliver Braunling

We construct a Hilbert scale on $L^2([0,1])$ via a unitary twist operator that maps the standard Fourier basis to half-integer frequency exponentials. The resulting weighted spaces, equipped with norms indexed by $(1+|k+\tfrac{1}{2}|^2)^s$,…

Functional Analysis · Mathematics 2026-01-19 Anik Chakraborty , Varinder Kumar

After recalling in detail some basic definitions on Hilbert C*-bimodules, Morita equivalence and imprimitivity, we discuss a spectral reconstruction theorem for imprimitivity Hilbert C*-bimodules over commutative unital C*-algebras and…

Operator Algebras · Mathematics 2008-12-19 Paolo Bertozzini , Roberto Conti , Wicharn Lewkeeratiyutkul

Let $p\in(1,\infty)$. We show that there is an isomorphism from any separable unital subalgebra of $B(\ell^{2})/K(\ell^{2})$ onto a subalgebra of $B(\ell^{p})/K(\ell^{p})$ that preserves the Fredholm index. As a consequence, every separable…

Operator Algebras · Mathematics 2024-09-12 March T. Boedihardjo

Naively, the analytic index of a family of self-adjoint Fredholm operators ought to be (an equivalence class of) the family of the kernels of these operators. The present paper is devoted to a rigorous version of this idea based on ideas of…

Differential Geometry · Mathematics 2023-02-09 Nikolai V. Ivanov

For differential operators which are invariant under the action of an abelian group Bloch theory is the preferred tool to analyze spectral properties. By shedding some new non-commutative light on this we motivate the introduction of a…

Mathematical Physics · Physics 2007-05-23 Michael J. Gruber

We extend the relative index theorem on non-compact manifolds to encompass a wide variety of hypoelliptic differential operators of arbitrary order, demonstrating that the change in index when changing a differential operator locally can be…

K-Theory and Homology · Mathematics 2025-11-11 Magnus Fries

The classical radial part formula for the invariant differential operators and the K-invariant functions on a Riemannian symmetric space G/K is generalized to some non-invariant cases by use of Cherednik operators and a graded Hecke algebra…

Representation Theory · Mathematics 2014-03-10 Hiroshi Oda
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