The ZOO of combinatorial Banach spaces

Fuente: arXiv
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Main Authors: Borodulin-Nadzieja, Piotr, Farkas, Barnabás, Jachimek, Sebastian, Pelczar-Barwacz, Anna
Format: Preprint
Published: 2024
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author Borodulin-Nadzieja, Piotr
Farkas, Barnabás
Jachimek, Sebastian
Pelczar-Barwacz, Anna
author_facet Borodulin-Nadzieja, Piotr
Farkas, Barnabás
Jachimek, Sebastian
Pelczar-Barwacz, Anna
contents We study Banach spaces induced by families of finite sets in the most natural (Schreier-like) way, that is, we consider the completion $X_\mc{F}$ of $c_{00}$ with respect to the norm $\sup\{\sum_{k\in F}|x(k)|:F\in\mc{F}\}$ where $\mc{F}$ is an arbitrary (not necessarily compact) family of finite sets covering $\mbb{N}$. Among other results, we discuss the following: (1) Structure theorems bonding the combinatorics of $\mc{F}$ and the geometry of $X_\mc{F}$ including possible characterizations and variants of the Schur property, $\ell_1$-saturation, and the lack of copies of $c_0$ in $X_\mc{F}$. (2) A plethora of examples including a relatively simple $\ell_1$-saturated combinatorial space which does not satisfy the Schur property, as well as a new presentation of Pełczyński's universal space. (3) The complexity of the family $\{H\subseteq\NN:X_{\mc{F}\upharpoonright H}$ does not contain $c_0\}$.
format Preprint
id arxiv_https___arxiv_org_abs_2404_01733
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The ZOO of combinatorial Banach spaces
Borodulin-Nadzieja, Piotr
Farkas, Barnabás
Jachimek, Sebastian
Pelczar-Barwacz, Anna
Functional Analysis
Logic
We study Banach spaces induced by families of finite sets in the most natural (Schreier-like) way, that is, we consider the completion $X_\mc{F}$ of $c_{00}$ with respect to the norm $\sup\{\sum_{k\in F}|x(k)|:F\in\mc{F}\}$ where $\mc{F}$ is an arbitrary (not necessarily compact) family of finite sets covering $\mbb{N}$. Among other results, we discuss the following: (1) Structure theorems bonding the combinatorics of $\mc{F}$ and the geometry of $X_\mc{F}$ including possible characterizations and variants of the Schur property, $\ell_1$-saturation, and the lack of copies of $c_0$ in $X_\mc{F}$. (2) A plethora of examples including a relatively simple $\ell_1$-saturated combinatorial space which does not satisfy the Schur property, as well as a new presentation of Pełczyński's universal space. (3) The complexity of the family $\{H\subseteq\NN:X_{\mc{F}\upharpoonright H}$ does not contain $c_0\}$.
title The ZOO of combinatorial Banach spaces
topic Functional Analysis
Logic
url https://arxiv.org/abs/2404.01733