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Continuing the study initiated in our earlier article [7], this paper aims to characterize various continuity properties of nonlinear composition operators acting on some sequence spaces, giving special attention to the space of sequences…

Functional Analysis · Mathematics 2025-05-13 Daria Bugajewska , Piotr Kasprzak

In this paper, we present a complete spectral research of generalized Ces\`aro operators on Sobolev-Lebesgue sequence spaces. The main idea is to subordinate such operators to suitable $C_0$-semigroups on these sequence spaces. We introduce…

Functional Analysis · Mathematics 2017-04-25 Luciano Abadia , Pedro J. Miana

In this paper, a new class of band matrices is considered where the entries of each non-zero band form a sequence with two limit points. The compact perturbation technique is used to study the spectrum over the $\ell_{p}, (1<p<\infty)$…

Spectral Theory · Mathematics 2025-01-22 Jyoti Rani , Arnab Patra , P D Srivastava

The relationship between the operator approximation property and the strong operator approximation property has deep significance in the theory of operator algebras. The original definitions of Effros and Ruan, unlike the classical…

Functional Analysis · Mathematics 2007-05-23 Corran Webster

In this article we address the question of characterizing the sequences of complex numbers $(\eta )=\{ \eta_n\}_{n=0}^\infty $ whose associated Rhaly operator $\mathcal R_{(\eta )}$ is bounded or compact on the Hardy spaces $H^p$ ($1\le…

Complex Variables · Mathematics 2025-12-18 Petros Galanopoulos , Daniel Girela

We derive the Euler-Lagrange equations for minimizers of causal variational principles in the non-compact setting with constraints, possibly prescribing symmetries. Considering first variations, we show that the minimizing measure is…

Mathematical Physics · Physics 2014-01-07 Yann Bernard , Felix Finster

In the paper compact multiplier operators on Banach spaces of analytic functions on the unit disk with the range in Banach sequence lattices are studied. If the domain space $X$ is such that $H_\infty\hookrightarrow X\hookrightarrow H_1$,…

Functional Analysis · Mathematics 2008-08-12 Paweł Mleczko

We consider the composition of operators with non-closed range in Hilbert spaces and how the nature of ill-posedness is affected by their composition. Specifically, we study the \mbox{Hausdorff-,} Ces\`{a}ro-, integration operator, and…

Functional Analysis · Mathematics 2024-05-17 Stefan Kindermann , Bernd Hofmann

Commutators of a large class of bilinear operators and multiplication by functions in a certain subspace of the space of functions of bounded mean oscillations are shown to be jointly compact. Under a similar commutation, fractional…

Classical Analysis and ODEs · Mathematics 2013-10-16 Árpád Bényi , Wendolín Damián , Kabe Moen , Rodolfo H. Torres

We characterize classes of linear maps between operator spaces $E$, $F$ which factorize through maps arising in a natural manner via the Pisier vector-valued non-commutative $L^p$ spaces $S_p[E^*]$ based on the Schatten classes on the…

funct-an · Mathematics 2008-02-03 Francesco Fidaleo

Let $\Delta^{(\alpha)}$ denote the fractional difference operator. In this paper, we define new difference sequence spaces $c_0(\Gamma,\Delta^{(\alpha)},u)$ and $c(\Gamma,\Delta^{(\alpha)},u)$. Also, the $\beta-$ dual of the spaces…

Functional Analysis · Mathematics 2014-08-07 Serkan Demiriz , Osman Duyar

The main objective of this paper is to introduced a new sequence space $l_{p}(\hat{F}(r,s)),$ $ 1\leq p \leq \infty$ by using the band matrix $\hat{F}(r,s).$ We also establish a few inclusion relations concerning this space and determine…

Functional Analysis · Mathematics 2016-04-04 Anupam Das , Bipan Hazarika

In this paper. we study properties such as $L^r$-boundedness, compactness, belonging to Schatten classes and nuclearity, Riesz spectral theory, Fredholmness, ellipticity and Gohberg's lemma, among others, for pseudo-differential operators…

Spectral Theory · Mathematics 2019-12-25 Juan Pablo Velasquez-Rodriguez

In this paper, we introduce a new class of subsets of bounded linear operators between Banach spaces which is p-version of the uniformly completely continuous sets. Then, we study the relationship between these sets with the equicompact…

Functional Analysis · Mathematics 2020-03-26 M. Alikhani

We find a lower bound for the essential norm of the difference of two composition operators acting on $H^2(B_N)$ or $A^2_s(B_N)$ ($s>-1$). This result plays an important role in proving a necessary and sufficient condition for the…

Complex Variables · Mathematics 2010-08-11 Liangying Jiang , Caiheng Ouyang

We analyze the properties of weakly compact sets in Lipschitz free spaces. Prior research has established that, for a complete metric space $M$, weakly precompact sets in the Lipschitz free space $\mathcal F(M)$ are tight. In this paper, we…

Functional Analysis · Mathematics 2026-02-16 Ramón J. Aliaga , Colin Petitjean , Antonín Prochazka , Triinu Veeorg

The notion of the truncated Euler characteristic for Iwasawa modules is a generalization of the the usual Euler characteristic to the case when the cohomology groups are not finite. Let $p$ be an odd prime, $E_1$ and $E_2$ be elliptic…

Number Theory · Mathematics 2023-02-27 Anwesh Ray , R. Sujatha

Given a compact metric graph $\Gamma$ and the Laplacian $\Delta_{\Gamma}$ coupled with standard (Kirchhoff) vertex conditions, solutions to fractional elliptic partial differential equations of the form $(\kappa^2 -…

Analysis of PDEs · Mathematics 2025-12-16 Elsiddig Awadelkarim , David Bolin , Alexandre B. Simas

In this paper, we determine the spectrum, the point spectrum, the continuous spectrum and the residual spectrum of the generalized difference operator $\Delta_{a,b}$ on the sequence space $\ell_p \ (1< p < \infty)$ where the real sequences…

Functional Analysis · Mathematics 2018-07-10 Riddhick Birbonshi , Arnab Patra , P. D. Srivastava

The aim of the paper is to introduced the spaces $c_{0}^{\lambda}(\hat{F})$ and $c^{\lambda}(\hat{F})$ which are the BK-spaces of non-absolute type and also derive some inclusion relations. Further, we determine the…

Functional Analysis · Mathematics 2016-04-27 Anupam Das , Bipan Hazarika