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Assuming the generalized continuum hypothesis we construct arbitrarily big indecomposable Banach spaces. i.e., such that whenever they are decomposed as $X\oplus Y$, then one of the closed subspaces $X$ or $Y$ must be finite dimensional. It…

Functional Analysis · Mathematics 2016-03-08 Piotr Koszmider , Saharon Shelah , Michał Świȩtek

Given a Dedekind incomplete ordered field, a pair of convergent nets of gaps which are respectively increasing or decreasing to the same point is used to obtain a further equivalent criterion for Dedekind completeness of ordered fields:…

General Topology · Mathematics 2007-05-23 Mojtaba Moniri , Jafar S. Eivazloo

In this work, we prove that linear bounded operators $T$ on a Banach space $X$ allowing spectral cuts along rectifiable Jordan curves meeting their spectrum are related to classes of operators admitting an unconventional functional…

Functional Analysis · Mathematics 2026-03-24 Eva A. Gallardo-Gutiérrez , F. Javier González-Doña

The notion of decomposable operators acting between distinct $L^p$-direct integrals of Banach spaces is introduced. We show that these operators generalize the composition operator, in sense that a mapping is replaced by a binary relation.…

Functional Analysis · Mathematics 2024-11-26 Nikita Evseev , Alexander Menovschikov

This is the second of two closely related papers on transversality. Here we introduce the notion of strong tangential transversality of two closed subsets of a Banach space which is a natural sufficient condition for tangential…

Optimization and Control · Mathematics 2018-10-09 Mira Bivas , Mikhail Krastanov , Nadezhda Ribarska

As a generalization of almost everywhere convergence to vector lattices, unbounded order convergence has garnered much attention. The concept of boundedly uo-complete Banach lattices was introduced by N. Gao and F. Xanthos, and has been…

Functional Analysis · Mathematics 2017-08-24 Mitchell A. Taylor

Very recently, Berinde and P\u{a}curar obtained in [V. Berinde and M. P\u{a}curar, Approximating fixed points of enriched contractions in Banach spaces. Journal of Fixed Point Theory and Applications. \textbf{22}(2) (2020), 1--10.] an…

Classical Analysis and ODEs · Mathematics 2022-09-27 Rizwan Anjum , Mujahid Abbas

Finiteness of the point spectrum of linear operators acting in a Banach space is investigated from point of view of perturbation theory. In the first part of the paper we present an abstract result based on analytical continuation of the…

Spectral Theory · Mathematics 2007-08-08 Igor Cialenco

We provide a concise proof of existence for nonlinear operator equations in separable Banach spaces. Notably, the operator is not assumed to be monotone. Instead, our main hypotheses consist of a continuity assumption and a generalized…

Analysis of PDEs · Mathematics 2025-03-21 Roland Becker , Malte Braack

It is shown that certain lower semi-continuous maps from a paracompact space to the family of closed subsets of the bundle space of a Banach bundle admit continuous selections. This generalization of the theorem of Douady, dal…

Functional Analysis · Mathematics 2016-04-19 Aldo J. Lazar

In this paper the general spectral properties of linear operators in Banach spaces are studied. We find sufficient conditions on structure of Banach spaces and resolvent properties that guarantee completeness of roots elements of Schatten…

Analysis of PDEs · Mathematics 2017-06-06 Veli Shakhmurov

We give orthonormal characterizations of collectively compact (limited) sets of linear operators from a Hilbert space to a Banach space.

Functional Analysis · Mathematics 2024-07-04 Svetlana Gorokhova

We prove a generalized contraction principle with control function in complete partial metric spaces. The contractive type condition used allows the appearance of self distance terms. The obtained result generalizes some previously obtained…

General Topology · Mathematics 2016-09-20 Thabet Abdeljawad , Younis Zaidan , Naseer Shahzad

Having as start point the classic definitions of resolvent set and spectrum of a linear bounded operator on a Banach space, we introduce the resolvent set and spectrum of a family of linear bounded operators on a Banach space. In addition,…

Functional Analysis · Mathematics 2012-07-11 Simona Macovei

We prove existence of small amplitude, $2\pi \slash \om$-periodic in time solutions of completely resonant nonlinear wave equations with Dirichlet boundary conditions, for any frequency $ \om $ belonging to a Cantor-like set of positive…

Analysis of PDEs · Mathematics 2007-05-23 M. Berti , P. Bolle

We establish a linear variational principle extending the Deville-Godefroy-Zizler's one. We use this variational principle to prove that if $X$ is a Banach space having property $(\alpha)$ of Schachermayer and $Y$ is any banach space, then…

Functional Analysis · Mathematics 2021-05-13 Mohammed Bachir

Using Mujica's linearization theorem, we extend to the holomorphic setting some classical characterizations of compact (weakly compact, Rosenthal, Asplund) linear operators between Banach spaces such as the Schauder, Gantmacher and…

Functional Analysis · Mathematics 2023-02-09 A. Jiménez-Vargas , D. Ruiz-Casternado , J. M. Sepulcre

We adapt the classical theory of local well-posedness of evolution problems to cases in which the nonlinearity can be accurately quantified by two different norms. For ordinary differential equations, we consider $\dot{x} = f(x,x)$ for a…

Analysis of PDEs · Mathematics 2024-03-01 Charles Bertucci , Pierre Louis Lions

After different variables and functions changes, the generalized dispersal problem, recalled in (1) below and considered in part I, see Labbas, Maingot and Thorel [14], leads us to consider, to study and to invert the sum of linear…

Analysis of PDEs · Mathematics 2024-03-06 Rabah Labbas , Stéphane Maingot , Alexandre Thorel

In this paper, we begin by constructing global linear maps on (n-2)-dimensional subspaces, derived from the local continuity of linear transformations among central sections of a convex body. Using these linear maps, we subsequently…

Functional Analysis · Mathematics 2026-04-07 Ning Zhang