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We introduce the notion of approximate norm attainment set of a bounded linear operator between Banach spaces and use it to obtain a complete characterization of smooth points in the space of compact linear operators, provided the domain…

Functional Analysis · Mathematics 2018-03-19 Debmalya Sain

We introduce the strong Gelfand-Phillips property for locally convex spaces and give several characterizations of this property. We characterize the strong Gelfand-Phillips property among locally convex spaces admitting a stronger Banach…

Functional Analysis · Mathematics 2021-11-11 Taras Banakh , Saak Gabriyelyan

Denote by $[0,\omega_1)$ the locally compact Hausdorff space consisting of all countable ordinals, equipped with the order topology, and let $C_0[0,\omega_1)$ be the Banach space of scalar-valued, continuous functions which are defined on…

Functional Analysis · Mathematics 2015-04-29 Tomasz Kania , Piotr Koszmider , Niels Jakob Laustsen

We prove that if $K$ and $L$ are compact spaces and $C(K)$ and $C(L)$ are isomorphic as Banach spaces then $K$ has a $\pi$-base consisting of open sets $U$ such that $\bar{U}$ is a continuous image of some compact subspace of $L$. This…

Functional Analysis · Mathematics 2013-09-20 Grzegorz Plebanek

A locally compact group $G$ has the factorization property if the map $$C^*(G)\odot C^*(G)\ni a\otimes b\mapsto \lambda(a)\rho(b)\in\mathcal B(L^2(G))$$ is continuous with respect to the minimal C*-norm. This paper seeks to initiate a…

Operator Algebras · Mathematics 2017-09-28 Matthew Wiersma

We give a classification of unitary representations of certain Polish, not necessarily locally compact, groups: the groups of all measurable functions with values in the circle and the groups of all continuous functions on compact, second…

Representation Theory · Mathematics 2014-09-23 Slawomir Solecki

One of the fundamental problem in rings of continuous function is to extract those spaces for which C(X) determines X, that is to investigate X and Y such that C(X) isomorphic with C(Y ) implies X homeomorphic with Y . The development…

General Topology · Mathematics 2022-04-20 Biswajit Mitra , Sanjib Das

We introduce new families of cylindric symmetric functions as subcoalgebras in the ring of symmetric functions $\Lambda$ (viewed as a Hopf algebra) which have non-negative structure constants. Combinatorially these cylindric symmetric…

Combinatorics · Mathematics 2019-07-05 Christian Korff , David Palazzo

We define Schatten classes of adjointable operators on Hilbert modules over abelian $C^*$-algebras. Many key features carry over from the Hilbert space case. In particular, the Schatten classes form two-sided ideals of compact operators and…

Operator Algebras · Mathematics 2020-10-16 Abel B. Stern , Walter D. van Suijlekom

We introduce notions of nearly good relations and N-sticky modulo a relation as tools for proving that spaces are D-spaces. As a corollary to general results about such relations, we show that C_p(X) is hereditarily a D-space whenever X is…

General Topology · Mathematics 2007-05-23 Gary Gruenhage

We study the classification of spaces of continuous functions $C(K)$ under positive linear maps. For infinite countable compacta, we show that whenever $C(K)$ and $C(L)$ are isomorphic, there exists an isomorphism $T:C(K)\to C(L)$…

Functional Analysis · Mathematics 2026-01-19 Marek Cúth , Jonáš Havelka , Jakub Rondoš , Bünyamin Sarı

We provide a sufficient condition for an operator $T$ on a non-metrizable and sequentially separable topological vector space $X$ to be sequentially hypercyclic. This condition is applied to some particular examples, namely, a composition…

Functional Analysis · Mathematics 2024-03-08 Alfred Peris

In computable topology, a represented space is called computably discrete if its equality predicate is semidecidable. While any such space is classically isomorphic to an initial segment of the natural numbers, the computable-isomorphism…

Logic · Mathematics 2025-12-12 Eike Neumann , Arno Pauly , Cécilia Pradic , Manlio Valenti

We establish several operator extensions of the Chebyshev inequality. The main version deals with the Hadamard product of Hilbert space operators. More precisely, we prove that if $\mathscr{A}$ is a $C^*$-algebra, $T$ is a compact Hausdorff…

Functional Analysis · Mathematics 2014-05-30 Mohammad Sal Moslehian , Mojtaba Bakherad

Let $K_\theta$ be a model space generated by an inner function $\theta$. We study the Schatten class membership of embeddings $I : K_\theta \to L^2(\mu)$, $\mu$ a positive measure, and of composition operators $C_\phi:K_\theta\to…

Functional Analysis · Mathematics 2016-03-24 A. Aleman , Yu. Lyubarskii , E. Malinnikova , K. -M. Perfekt

Given a finite alphabet $\Lambda$, and a not necessarily finite type subshift $X\subseteq \Lambda^\infty$, we introduce a partial action of the free group $F(\Lambda)$ on a certain compactification $\Omega_X$ of $X$, which we call the…

Operator Algebras · Mathematics 2015-11-04 M. Dokuchaev , R. Exel

There have been many parallel streams of research studying order isomorphisms of some specific sets $G$ of functions from a set $X$ to $\mathbb{R}\cup\{\pm\infty\}$, such as the sets of convex or Lipschitz functions. We develop in this…

Functional Analysis · Mathematics 2025-08-12 Pierre-Cyril Aubin-Frankowski , Stéphane Gaubert

We introduce new vanishing subspaces of the homogeneous H\"{o}lder space $\dot{C}^{0,\omega}(X,Y)$ in the generality of a doubling modulus $\omega$ and normed spaces $X$ and $Y.$ For many couples $X,Y,$ we show these vanishing subspaces to…

Functional Analysis · Mathematics 2025-12-08 Carlos Mudarra , Tuomas Oikari

A Tychonoff space $X$ is called ({\em sequentially}) {\em Ascoli} if every compact subset (resp. convergent sequence) of $C_k(X)$ is evenly continuous, where $C_k(X)$ denotes the space of all real-valued continuous functions on $X$ endowed…

General Topology · Mathematics 2020-04-02 Saak Gabriyelyan

A set of all symmetric Banach function spaces defined on [0,1] is equipped with the partial order by the relation of continuous inclusion. Properties of symmetric spaces, which do not depend of their position in the ordered structure, are…

Functional Analysis · Mathematics 2007-05-23 Eugene Tokarev