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This paper explores the concept of $K$-$g$-frames in locally $C^*$-algebras, which are shown to be more general than $g$-frames. The authors first introduce the notion of a $g$-orthonormal basis and utilize it to define the $g$-operator, a…

Operator Algebras · Mathematics 2024-05-30 Roumaissae Eljazzar , Mohammed Mouniane , Mohamed Rossafi

We introduce a localization concept for operator-valued frames, where the quality of localization is measured by the associated operator-valued Gram matrix belonging to some suitable Banach algebra. We prove that intrinsic localization of…

Functional Analysis · Mathematics 2025-05-29 Lukas Köhldorfer , Peter Balazs

Loosely speaking, a semi-frame is a generalized frame for which one of the frame bounds is absent. More precisely, given a total sequence in a Hilbert space, we speak of an upper (resp. lower) semi-frame if only the upper (resp. lower)…

Functional Analysis · Mathematics 2012-05-31 Jean-Pierre Antoine , Peter Balazs

In this paper, we aim to introduce and characterize the concept of numerical radius orthogonality of operators on a complex Hilbert space $\mathcal{H}$ which are bounded with respect to the semi-norm induced by a positive operator $A$ on…

Functional Analysis · Mathematics 2024-08-13 Pintu Bhunia , Kais Feki , Kallol Paul

We study operator spaces, operator algebras, and operator modules, from the point of view of the `noncommutative Shilov boundary'. In this attempt to utilize some `noncommutative Choquet theory', we find that Hilbert C$^*-$modules and their…

Operator Algebras · Mathematics 2007-05-23 David P. Blecher

We apply Lax-Milgram theorem to characterize scalable and piecewise scalable frame in finite and infinite-dimensional Hilbert spaces. We also introduce a method for approximating the inverse frame operator using finite-dimensional linear…

Functional Analysis · Mathematics 2022-12-05 Laura De Carli , Pierluigi Vellucci

We introduce the notion of a generalized fusion frame in quaternionic Hilbert space. A characterization of generalized fusion frame in quaternionic Hilbert space with the help of frame operator is being discussed. Finally, we construct…

Functional Analysis · Mathematics 2024-04-08 Prasenjit Ghosh

This article aims to explore the most recent developments in the study of the Hilbert matrix, acting as an operator on spaces of analytic functions and sequence spaces. We present the latest advances in this area, aiming to provide a…

Functional Analysis · Mathematics 2024-11-04 Carlo Bellavita , Vassilis Daskalogiannis , Georgios Stylogiannis

We present an inequality for tensor product of positive operators on Hilbert spaces by considering the tensor product of operators as words on certain alphabets (i.e., a set of letters). As applications of the operator inequality and by a…

Functional Analysis · Mathematics 2015-02-23 Xaixia Chang , Vehbi E. Paksoy , Fuzhen Zhang

Controlled g-atomic subspace for a bounded linear operator is being presented and a characterization has been given. We give an example of controlled K-g-fusion frame. We construct a new controlled K-g-fusion frame for the Hilbert space H ?…

Functional Analysis · Mathematics 2023-03-29 Prasenjit Ghosh , T. K. Samanta

Functional analysis, especially the theory of Hilbert spaces and of operators on these, form an important area in mathematics. We formalized the Isabelle/HOL library Complex_Bounded_Operators containing a large amount of theorems about…

Logic in Computer Science · Computer Science 2025-12-08 Dominique Unruh , José Manuel Rodríguez Caballero

We present results about minimization of convex functionals defined over a finite set of vectors in a finite dimensional Hilbert space, that extend several known results for the Benedetto-Fickus frame potential. Our approach depends on…

Functional Analysis · Mathematics 2007-10-08 Pedro Massey , Mariano Ruiz

In this paper we consider A-Fredholm and semi-A-Fredholm operators on Hilbert C*-modules over a W*-algebra A defined in [3],[10]. Using the assumption that A is a W*-algebra (and not an arbitrary C*-algebra), we obtain several results such…

Operator Algebras · Mathematics 2020-02-18 Stefan Ivkovic

In this paper we try to prepare a framework for field quantization. To this end, we aim to replace the field of scalars R by self-adjoint elements of a commutative C-algebra, and reach an appropriate generalization of geometrical concepts…

Mathematical Physics · Physics 2015-01-28 Hassan Feizabadi , Nasser Boroojerdian

This paper is a contribution to the theory of dynamical sampling. Our purpose is twofold. We first consider representations of sequences in a Hilbert space in terms of iterated actions of a bounded linear operator. This generalizes recent…

Functional Analysis · Mathematics 2020-09-11 Ole Christensen , Marzieh Hasannasab , Diana T. Stoeva

The theory of one-sided $M$-ideals and multipliers of operator spaces is simultaneously a generalization of classical $M$-ideals, ideals in operator algebras, and aspects of the theory of Hilbert $C^*$-modules and their maps. Here we give a…

Operator Algebras · Mathematics 2007-05-23 David P. Blecher , Vrej Zarikian

In this paper, we give some results concerning atomic decompositions for operators on reproducing kernel Hilbert spaces, using frame theory techniques. We provide also generalizations for atomic decompositions of some theorems for…

Functional Analysis · Mathematics 2014-02-03 Laura Gavruta

Let $S\in\mathcal{M}_d(\mathbb{C})^+$ be a positive semidefinite $d\times d$ complex matrix and let $\mathbf a=(a_i)_{i\in\mathbb{I}_k}\in \mathbb{R}_{>0}^k$, indexed by $\mathbb{I}_k=\{1,\ldots,k\}$, be a $k$-tuple of positive numbers. Let…

Functional Analysis · Mathematics 2018-12-27 Pedro Massey , Noelia Rios , Demetrio Stojanoff

We introduce and study some new uniform structures for Hilbert $C^*$-modules over an algebra $A$. In particular, we prove that in some cases they have the same totally bounded sets. To define one of them, we introduce a new class of…

Operator Algebras · Mathematics 2024-02-29 Denis Fufaev , Evgenij Troitsky

We provide several perturbation theorems regarding closable operators on a real or complex Hilbert space. In particular we extend some classical results due to Hess--Kato, Kato--Rellich and W\"ust. Our approach involves ranges of matrix…

Functional Analysis · Mathematics 2014-09-22 Dan Popovici , Zoltán Sebestyén , Zsigmond Tarcsay