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We investigate the structure of norm-preserving and linear but not necessarily surjective operators on variable-exponent, discrete Lebesgue spaces. A certain class of isometries, novel to this work, are especially considered; this class…

Functional Analysis · Mathematics 2020-07-13 Philip M. Gipson

A quasi-Hermitian operator is an operator that is similar to its adjoint in some sense, via a metric operator, i.e., a strictly positive self-adjoint operator. Whereas those metric operators are in general assumed to be bounded, we analyze…

Mathematical Physics · Physics 2014-09-12 Jean-Pierre Antoine , Camillo Trapani

In this paper, we study weighted composition operators on the Fock space. We show that a weighted composition operator is cohyponorma if and only if it is normal. Moreover, we give a complete characterization of closed range weighted…

Functional Analysis · Mathematics 2018-09-14 Mahsa Fatehi

We investigate the isometric composition operators on the analytic Besov spaces. For $1<p<2$ we show that an isometric composition operator is induced only by a rotation of the disk. For $p>2$, we extend previous work on the subject.…

Functional Analysis · Mathematics 2022-07-27 Robert F. Allen , Katherine Heller , Matthew A. Pons

In this paper we study the self-adjoint and co-isometry composition and weighted composition operator on $H_E(\zeta).$ We also discuss the conditions under which adjoint operator of a composition and weighted composition operator on…

Functional Analysis · Mathematics 2021-10-11 Anuradha Gupta , Geeta Yadav

In this paper we consider composition operators on Harmonic-Bloch type spaces and we compute the spectrum of composition operators. Also, we characterize isometric composition operators on harmonic Bloch type spaces.

Functional Analysis · Mathematics 2022-02-15 Y. Estaremi , A. Ebadian , S. Esmaeili

In this paper, we characterize all closed linear operators in a separable Hilbert space which are unitarily equivalent to an integral bi-Carleman operator in $L_2(R)$ with bounded and arbitrarily smooth kernel on $R^2$. In addition, we give…

Spectral Theory · Mathematics 2007-05-23 Igor M. Novitskii

We consider cyclic $m$-isometries on a complex separable Hilbert space. Such operators are characterized in terms of shifts on abstract spaces of weighted Dirichlet type. Our results resemble those of Agler and Stankus, but our model spaces…

Functional Analysis · Mathematics 2018-12-05 Eskil Rydhe

In this paper we find all complex symmetric weighted composition operators with special conjugations. Then we give spectral properties of these complex symmetric weighted composition operators.

Functional Analysis · Mathematics 2018-04-10 Mahsa Fatehi

A complete characterisation is given of all the linear isometries of the Fr\'echet space of all holomorphic functions on the unit disc, when it is given one of the two standard metrics: these turn out to be weighted composition operators of…

Complex Variables · Mathematics 2024-05-17 I. Chalendar , L. Oger , J. R. Partington

We study composition operators on the weighted Banach spaces of an infinite tree. We characterize the bounded and the compact operators, as well as determine the operator norm and the essential norm. In addition, we study the isometric…

Functional Analysis · Mathematics 2022-07-26 Robert F. Allen , Matthew A. Pons

Fix a metric space $M$ and let $\mathrm{Lip}_0(M)$ be the Banach space of complex-valued Lipschitz functions defined on $M$. A weighted composition operator on $\mathrm{Lip}_0(M)$ is an operator of the kind $wC_f : g \mapsto w \cdot g \circ…

Functional Analysis · Mathematics 2023-10-16 Arafat Abbar , Clément Coine , Colin Petitjean

A quasi-Hermitian operator is an operator that is similar to its adjoint in some sense, via a metric operator, i.e., a strictly positive self-adjoint operator. Whereas those metric operators are in general assumed to be bounded, we analyze…

Mathematical Physics · Physics 2016-10-24 Jean-Pierre Antoine , Camillo Trapani

A pair of Hilbert space linear operators $(V_1,V_2)$ is said to be $q$-commutative, for a unimodular complex number $q$, if $V_1V_2=qV_2V_1$. A concrete functional model for $q$-commutative pairs of isometries is obtained. The functional…

Functional Analysis · Mathematics 2022-07-05 Joseph A. Ball , Haripada Sau

We describe the Aluthge transform of an unbounded weighted composition operator acting in an $L^2$-space. We show that its closure is also a weighted composition operator with the same symbol and a modified weight function. We investigate…

Functional Analysis · Mathematics 2024-11-27 Chafiq Benhida , Piotr Budzynski , Jacek Trepkowski

We obtain some results about the spectrum and the upper semi-Fredholm spectrum of weighted composition operators on uniform algebras, assuming that the corresponding map maps the Shilov boundary onto itself. In particular, it follows from…

Spectral Theory · Mathematics 2024-01-31 Arkady Kitover , Mehmet Orhon

In this paper we consider composition operators on Hardy-Sobolev spaces in connections with $BMO$-quasiconformal mappings. Using the duality of Hardy spaces and $BMO$-spaces we prove that $BMO$-quasiconformal mappings generate bounded…

Analysis of PDEs · Mathematics 2021-05-18 Alexander Menovschikov , Alexander Ukhlov

The aim of this article is to detect the ascent and descent of weighted composition operators on Lorentz spaces. We investigate the conditions on the measurable transformation $T$ and the complex-valued measurable function $u$ defined on…

Functional Analysis · Mathematics 2024-04-26 Gopal Datt , Daljeet Singh Bajaj

We study composition operators whose symbols are suitable perturbations of the identity and which act between different weighted modulation classes. We consider both modulation spaces formed by tempered distributions and those whose…

Functional Analysis · Mathematics 2025-12-18 Héctor Ariza , Carmen Fernández , Antonio Galbis

We study when multiplication by a weight can turn a non-compact composition operator on H 2 into a compact operator, and when it can be in Schatten classes. The q-summing case in H p is considered. We also study when this multiplication can…

Functional Analysis · Mathematics 2019-04-16 Pascal Lefèvre , Daniel Li , Hervé Queffélec , Luis Rodriguez-Piazza