When is the Szlenk derivation of a dual unit ball another ball?

Fuente: arXiv
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Autori principali: Kochanek, Tomasz, Miarka, Marek
Natura: Preprint
Pubblicazione: 2024
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author Kochanek, Tomasz
Miarka, Marek
author_facet Kochanek, Tomasz
Miarka, Marek
contents We show that if a separable Banach space has Kalton's property $(M^\ast)$, then all $\varepsilon$-Szlenk derivations of the dual unit ball are balls, however, in the case of the dual of Baernstein's space, all those Szlenk derivations are balls having the same radius as for $\ell_2$, yet this space fails property $(M^\ast)$. By estimating the radii of enveloping balls, we show that the Szlenk derivations are not balls for Tsirelson's space and the dual of Schlumprecht's space. Using the Karush-Kuhn-Tucker theorem we prove that the same is true for the duals of certain sequential Orlicz spaces.
format Preprint
id arxiv_https___arxiv_org_abs_2409_05516
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle When is the Szlenk derivation of a dual unit ball another ball?
Kochanek, Tomasz
Miarka, Marek
Functional Analysis
We show that if a separable Banach space has Kalton's property $(M^\ast)$, then all $\varepsilon$-Szlenk derivations of the dual unit ball are balls, however, in the case of the dual of Baernstein's space, all those Szlenk derivations are balls having the same radius as for $\ell_2$, yet this space fails property $(M^\ast)$. By estimating the radii of enveloping balls, we show that the Szlenk derivations are not balls for Tsirelson's space and the dual of Schlumprecht's space. Using the Karush-Kuhn-Tucker theorem we prove that the same is true for the duals of certain sequential Orlicz spaces.
title When is the Szlenk derivation of a dual unit ball another ball?
topic Functional Analysis
url https://arxiv.org/abs/2409.05516