Diversity of Lipschitz-free spaces over countable complete discrete metric spaces

Fuente: arXiv
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Auteurs principaux: Basset, Estelle, Lancien, Gilles, Procházka, Antonín
Format: Preprint
Publié: 2025
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author Basset, Estelle
Lancien, Gilles
Procházka, Antonín
author_facet Basset, Estelle
Lancien, Gilles
Procházka, Antonín
contents We show that there are uncountably many mutually non-isomorphic Lipschitz-free spaces over countable, complete, discrete metric spaces. Also there is a countable, complete, discrete metric space whose free space does not embed into the free space of any uniformly discrete metric space. This enhanced diversity is a consequence of the fact that the dentability index $D$ presents a highly non-binary behavior when assigned to the free spaces of metric spaces outside of the oppressive confines of compact purely 1-unrectifiable spaces. Indeed, the cardinality of $\{D(\mathcal F(M)): M$ countable, complete, discrete$\}$ is uncountable while $\{D(\mathcal F(M)):M$ infinite, compact, purely 1-unrectifiable$\}=\{ω,ω^2\}$. Similar barrier is observed for uniformly discrete metric spaces as higher values of the dentability index are excluded for their free spaces: $\{D(\mathcal F(M)):M$ infinite, uniformly discrete$\}=\{ω^2,ω^3\}$.
format Preprint
id arxiv_https___arxiv_org_abs_2505_19891
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Diversity of Lipschitz-free spaces over countable complete discrete metric spaces
Basset, Estelle
Lancien, Gilles
Procházka, Antonín
Functional Analysis
Metric Geometry
46B20, 46B22, 51F30, 30L05, 54E45
We show that there are uncountably many mutually non-isomorphic Lipschitz-free spaces over countable, complete, discrete metric spaces. Also there is a countable, complete, discrete metric space whose free space does not embed into the free space of any uniformly discrete metric space. This enhanced diversity is a consequence of the fact that the dentability index $D$ presents a highly non-binary behavior when assigned to the free spaces of metric spaces outside of the oppressive confines of compact purely 1-unrectifiable spaces. Indeed, the cardinality of $\{D(\mathcal F(M)): M$ countable, complete, discrete$\}$ is uncountable while $\{D(\mathcal F(M)):M$ infinite, compact, purely 1-unrectifiable$\}=\{ω,ω^2\}$. Similar barrier is observed for uniformly discrete metric spaces as higher values of the dentability index are excluded for their free spaces: $\{D(\mathcal F(M)):M$ infinite, uniformly discrete$\}=\{ω^2,ω^3\}$.
title Diversity of Lipschitz-free spaces over countable complete discrete metric spaces
topic Functional Analysis
Metric Geometry
46B20, 46B22, 51F30, 30L05, 54E45
url https://arxiv.org/abs/2505.19891