PL EN

Preferencje
Język
Widoczny [Schowaj] Abstrakt
Liczba wyników
Czasopismo

Studia Mathematica

2009 | 192 | 1 | 15-27
Tytuł artykułu

Minimal ball-coverings in Banach spaces and their application

Autorzy
Treść / Zawartość
Warianty tytułu
Języki publikacji
EN
Abstrakty
EN
By a ball-covering 𝓑 of a Banach space X, we mean a collection of open balls off the origin in X and whose union contains the unit sphere of X; a ball-covering 𝓑 is called minimal if its cardinality $𝓑^{#}$ is smallest among all ball-coverings of X. This article, through establishing a characterization for existence of a ball-covering in Banach spaces, shows that for every n ∈ ℕ with k ≤ n there exists an n-dimensional space admitting a minimal ball-covering of n + k balls. As an application, we give a new characterization of superreflexive spaces in terms of ball-coverings. Finally, we show that every infinite-dimensional Banach space admits an equivalent norm such that there is an infinite-dimensional quotient space possessing a countable ball-covering.
Słowa kluczowe
Kategorie tematyczne
Czasopismo
Rocznik
Tom
Numer
Strony
15-27
Opis fizyczny
Daty
wydano
2009
Twórcy
autor
• Department of Mathematics, Xiamen University, Xiamen 361005, China
autor
• Department of Mathematics, Xiamen University, Xiamen 361005, China
autor
• Department of Mathematics, Xiamen University, Xiamen 361005, China
Bibliografia
Typ dokumentu
Bibliografia
Identyfikatory