The ball fixed point property in spaces of continuous functions

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Main Authors: Avilés, Antonio, Japón, María, Lennard, Christopher, Cervantes, Gonzalo Martínez, Stawski, Adam
Format: Preprint
Published: 2025
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author Avilés, Antonio
Japón, María
Lennard, Christopher
Cervantes, Gonzalo Martínez
Stawski, Adam
author_facet Avilés, Antonio
Japón, María
Lennard, Christopher
Cervantes, Gonzalo Martínez
Stawski, Adam
contents A Banach space $X$ has the ball fixed point property (BFPP) if for every closed ball $B$ and for every nonexpansive mapping $T\colon B\to B$, there is a fixed point. We study the BFPP for $C(K)$-spaces. Our goal is to determine topological properties over $K$ that may determine the failure or fulfillment of the BFPP for the space of continuous functions $C(K)$. We prove that the class of compact spaces $K$ for which the BFPP holds lies between the class of extremally disconnected compact spaces and the class of compact $F$-spaces. We give a family of examples of $F$-spaces $K$ for which the BFPP fails. As a result, we prove that for every cardinal $κ$, $κ$-order completeness or $κ$-hyperconvexity of $C(K)$ are not enough for the BFPP and we obtain that $\ell_\infty/c_0 = C(\mathbb{N}^*)$ fails BFPP under the Continuum Hypothesis. The space $C([0,+\infty)^*)$ is also analyzed. It is left as an open problem whether all compact spaces for which the BFPP holds are in fact the extremally disconnected compact sets.
format Preprint
id arxiv_https___arxiv_org_abs_2506_17995
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The ball fixed point property in spaces of continuous functions
Avilés, Antonio
Japón, María
Lennard, Christopher
Cervantes, Gonzalo Martínez
Stawski, Adam
Functional Analysis
General Topology
46B06, 46B26, 46E15, 54H25, 54E40, 54G05
A Banach space $X$ has the ball fixed point property (BFPP) if for every closed ball $B$ and for every nonexpansive mapping $T\colon B\to B$, there is a fixed point. We study the BFPP for $C(K)$-spaces. Our goal is to determine topological properties over $K$ that may determine the failure or fulfillment of the BFPP for the space of continuous functions $C(K)$. We prove that the class of compact spaces $K$ for which the BFPP holds lies between the class of extremally disconnected compact spaces and the class of compact $F$-spaces. We give a family of examples of $F$-spaces $K$ for which the BFPP fails. As a result, we prove that for every cardinal $κ$, $κ$-order completeness or $κ$-hyperconvexity of $C(K)$ are not enough for the BFPP and we obtain that $\ell_\infty/c_0 = C(\mathbb{N}^*)$ fails BFPP under the Continuum Hypothesis. The space $C([0,+\infty)^*)$ is also analyzed. It is left as an open problem whether all compact spaces for which the BFPP holds are in fact the extremally disconnected compact sets.
title The ball fixed point property in spaces of continuous functions
topic Functional Analysis
General Topology
46B06, 46B26, 46E15, 54H25, 54E40, 54G05
url https://arxiv.org/abs/2506.17995