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Related papers: Uniform lamda-adjustment and mu-approximation in B…

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Based on the recently introduced uniform $\lambda-$adjustment for closed subspaces of Banach spaces we extend the concept of the strictly singular and finitely strictly singular operators to the sequences of closed subspaces and operators…

Functional Analysis · Mathematics 2009-02-19 Boris Burshteyn

In this paper, the notion of semi-compact perturbation of a closed linear subspace is introduced. Then for a of pair of closed linear subspace of a Banach space such that one is a semi-compact perturbation of the other, it is proved that…

Functional Analysis · Mathematics 2025-10-28 Chenfeng Liao , Chaofeng Zhu

The concept of adjusted sublevel set for a quasiconvex function was introduced in \cite{AuHa05} and the local existence of a norm-to-weak$^*$ upper semicontinuous base-valued submap of the normal operator associated to the adjusted sublevel…

Optimization and Control · Mathematics 2023-01-31 Marco Castellani , Massimiliano Giuli

We study uniform $\epsilon-$BPB approximations of bounded linear operators between Banach spaces from a geometric perspective. We show that for sufficiently small positive values of $\epsilon,$ many geometric properties like smoothness,…

Functional Analysis · Mathematics 2024-08-14 Debmalya Sain , Arpita Mal , Kalidas Mandal , Kallol Paul

We consider the effect of perturbations to a quasi-linear parabolic stochastic differential equation set in a UMD Banach space $X$. To be precise, we consider perturbations of the linear part, i.e. the term concerning a linear operator $A$…

Functional Analysis · Mathematics 2012-03-08 Sonja Cox , Erika Hausenblas

Let X be a Banach Space over K=R or C, and let f:=F+C be a weakly coercive operator from X onto X, where F is a C^1-operator, and C a C^1 compact operator. Sufficient conditions are provided to assert that the perturbed operator f is a…

Functional Analysis · Mathematics 2020-07-10 José María Soriano Arbizu , Manuel Odóñez Cabrera

Existence and uniqueness as well as the iterative approximation of fixed points of enriched almost contractions in Banach spaces are studied. The obtained results are generalizations of the great majority of metric fixed point theorems, in…

Functional Analysis · Mathematics 2021-03-19 Vasile Berinde , Madalina Pacurar

We study Birkhoff-James orthogonality of compact (bounded) linear operators between Hilbert spaces and Banach spaces. Applying the notion of semi-inner-products in normed linear spaces and some related geometric ideas, we generalize and…

Functional Analysis · Mathematics 2018-10-12 Debmalya Sain , Kallol Paul , Arpita Mal

Recently, versions of neural networks with infinite-dimensional affine operators inside the computational units (``neural operator'' networks) have been applied to learn solutions to differential equations. To enable practical computations,…

Functional Analysis · Mathematics 2026-02-03 Vinícius Luz Oliveira , Vladimir G. Pestov

In this paper, by dilation technique on Schauder frames, we extend Godefroy and Kalton's approximation theorem (1997), and obtain that a separable Banach space has the $\lambda$-unconditional bounded approximation property ($\lambda$-UBAP)…

Functional Analysis · Mathematics 2025-07-04 Qiyao Bao , Rui Liu , Jie Shen

In this paper we study operators originated from semi-B-Fredholm theory and as a consequence we get some results regarding boundaries and connected hulls of the corresponding spectra. In particular, we prove that a bounded linear operator…

Spectral Theory · Mathematics 2018-10-03 Snežana Č. Živković-Zlatanović , Mohammed Berkani

This paper investigates strong metric subregularity around a reference point as introduced by H. Gfrerer and J. V. Outrata. In the setting of Banach spaces, we analyse its stability under Lipschitz continuous perturbations and establish its…

Optimization and Control · Mathematics 2025-05-07 Tomáš Roubal

We study best approximations to compact operators between Banach spaces and Hilbert spaces, from the point of view of Birkhoff-James orthogonality and semi-inner-products. As an application of the present study, some distance formulae are…

Functional Analysis · Mathematics 2021-04-30 Debmalya Sain

The existence of a solution, convergence and stability of the penalty method for variational inequalities with nonsmooth unbounded uniformly and properly monotone operators in Banach spase $B$ are investigated. All the objects of the…

funct-an · Mathematics 2008-02-03 Ya. I. Alber

We introduce a weakened notion of norm attainment for bounded linear operators between Banach spaces which we call \emph{quasi norm attaining operators}. An operator $T\colon X \longrightarrow Y$ between the Banach spaces $X$ and $Y$ is…

Functional Analysis · Mathematics 2020-04-24 Geunsu Choi , Yun Sung Choi , Mingu Jung , Miguel Martin

In this paper, we prove the stability theorems for the isotropic perturbations of maximal isotropic subspaces in symplectic Banach spaces. Then we prove a stability theorem for the mod $2$ dimensions of kernel of skew-adjoint linear…

Functional Analysis · Mathematics 2025-10-28 Hanchen Li , Chaofeng Zhu

Let $\Lambda$ be an open set in Banach space $E$, $M(x)$ for $x\in \Lambda $ be a subspace in $E$, and $x_0$ be a point in $\Lambda $. We consider the family $\mathcal{F}=\{M(x):\forall x\in\Lambda\}$, but the dimension of $M(x)$ can be…

Functional Analysis · Mathematics 2026-01-06 Jipu Ma

In this paper, we will see that the Cartesian product of two 2-Banach spaces is also 2-Banach space and discuss some properties of closed linear operator in linear 2-normed space. We also describe the concept of different types of…

Functional Analysis · Mathematics 2021-01-05 Prasenjit Ghosh , Sanjay Roy , T. K. Samanta

We present the current results in the study of weighted composition operators on weighted Banach spaces of an unbounded, locally finite metric space. Specifically, we determine characterizations of bounded and compact weighted composition…

Functional Analysis · Mathematics 2022-07-28 Robert F. Allen , Matthew A. Pons

This paper focuses on the stability of both local and global error bounds for a proper lower semicontinuous convex function defined on a Banach space. Without relying on any dual space information, we first provide precise estimates of…

Optimization and Control · Mathematics 2024-10-08 Zhou Wei , Michel Théra , Jen-Chih Yao
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