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We investigate the generalized derivations and show that every generalized derivation on a simple Hilbert $C^*$-module either is closable or has a dense range. We also describe dynamical systems on a full Hilbert $C^*$-module ${\mathcal M}$…

Operator Algebras · Mathematics 2021-07-23 Gh. Abbaspour , M. S. Moslehian , A. Niknam

For a separable complex Hilbert space $H$, we say that a bounded linear operator $T$ acting on $H$ is $C$-normal, where $C$ is a conjugation on $H$, if it satisfies $CT^*TC=TT^*$. For a normal operator, we give geometric conditions which…

Functional Analysis · Mathematics 2022-04-12 Zouheir Amara , Mourad Oudghiri

A semiregular operator on a Hilbert C^*-module, or equivalently, on the C^*-algebra of `compact' operators on it, is a closable densely defined operator whose adjoint is also densely defined. It is shown that for operators on extensions of…

Operator Algebras · Mathematics 2016-09-07 Arupkumar Pal

A regular operator T on a Hilbert C^*-module is defined just like a closed operator on a Hilbert space, with the extra condition that the range of (I+T^*T) is dense. Semiregular operators are a slightly larger class of operators that may…

Operator Algebras · Mathematics 2007-05-23 Arupkumar Pal

K-frame theory was recently introduced to reconstruct elements from the range of a bounded linear operator K in a separable Hilbert space. This significant property is worthwhile especially in some problems arising in sampling theory. Some…

Functional Analysis · Mathematics 2017-05-30 Fahimeh Arabyani Neyshaburi , Ghadir Mohajeri Minaei , Ehsan Anjidani

The stability theorem for persistent homology is a central result in topological data analysis. While the original formulation of the result concerns the persistence barcodes of $\mathbb{R}$-valued functions, the result was later cast in a…

Algebraic Topology · Mathematics 2018-10-24 Magnus Bakke Botnan , Michael Lesnick

Extending the concept of frame to continuous frame, in this manuscript we will show that under certain conditions on the measure of $\Omega$ and the dimension of $\h$ we can construct continuous frames. Also, some examples are given.

Functional Analysis · Mathematics 2016-06-30 Asghar Rahimi , Bayaz Daraby , Zahra Darvishi

In this paper, we characterize and study the concept of controlled continuous $g$-frame which is an extension of continuous $g$-frame in Hilbert spaces. We introduce the concept of controlled continuous dual $g$-frame and observe some…

Functional Analysis · Mathematics 2022-10-25 Mohamed Rossafi , Fakhr-dine Nhari , P. Sam Johnson

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

In this paper we study the concept of controlled $\ast$-operator frmae for $End_{\mathcal{A}}^{\ast}(\mathcal{H})$. Also we discuss characterizations of controlled $\ast$-operator frames and we give some properties

Functional Analysis · Mathematics 2020-09-29 Abdeslam Touri , Hatim Labrigui , Samir Kabbaj

It is well known that the boundary dynamics of vortex patches is globally well-posed in the H\"older space $C^{1,\alpha}$ for $0<\alpha<1$, whereas the well-posedness in $C^1$ remains an open problem, even locally. In this paper, we…

Analysis of PDEs · Mathematics 2025-10-01 Seungjae Lee

When the steady states at infinity become unstable through a pattern forming bifurcation, a travelling wave may bifurcate into a modulated front which is time-periodic in a moving frame. This scenario has been studied by B.Sandstede and…

Analysis of PDEs · Mathematics 2007-05-23 Thierry Gallay , Guido Schneider , Hannes Uecker

This paper presents an overview of close parallels that exist between the theory of positive operator-valued measures (POVMs) associated with a separable Hilbert space and the theory of frames on that space, including its most important…

Functional Analysis · Mathematics 2011-11-08 Bill Moran , Stephen Howard , Doug Cochran

This paper is concerned with the implications of sufficient conditions ensuring that a perturbation of a frame is again a frame. We emphasize how stability of frames is fundamental for numerical applications and we discuss in particular the…

Functional Analysis · Mathematics 2007-05-23 Massimo Fornasier

Controlled frames in Hilbert spaces have been introduced by Balazs, Antoine and Grybos to improve the numerical output of in relation to algorithms for inverting the frame operator. In this paper we have introduced and displayed some new…

Functional Analysis · Mathematics 2018-05-02 Habib shakoory , Reza Ahmadi , Naghi Behzadi , Susan Nami

Spontaneous pattern formation in a variety of spatially extended nonlinear system always occurs through a modulation instability: homogeneous state of the system becomes unstable with respect to growing modulation modes. Therefore, the…

Pattern Formation and Solitons · Physics 2015-08-25 S. Kumar , R. Herrero , M. Botey , K. Staliunas

G\v avruta studied atomic systems in terms of frames for range of operators (that is, for subspaces), namely $K$-frames, where the lower frame condition is controlled by the Hilbert-adjoint of a bounded linear operator $K$. For a locally…

Functional Analysis · Mathematics 2023-02-09 Jyoti , Lalit Kumar Vashisht , Uttam Kumar Sinha

Subject of the paper deals with the perturbation theory of linear operators acting in Hilbert space. For a certain class of perturbations the question is considered about existence of transformation operators implementing linear similarity…

Functional Analysis · Mathematics 2017-11-08 S. A. Stepin

This paper is devoted to study discrete and continuous bases for spaces supporting representations of SO(3) and SO(3,2) where the spherical harmonics are involved. We show how discrete and continuous bases coexist on appropriate choices of…

Mathematical Physics · Physics 2018-05-23 E. Celeghini , M. Gadella , M. A. del Olmo

The theory of multiplier modules of Hilbert C*-modules is reconsidered to obtain more properties of these special Hilbert C*-modules. The property of a Hilbert C*-module to be a multiplier C*-module is shown to be an invariant with respect…

Operator Algebras · Mathematics 2026-03-26 Michael Frank