Isometric rigidity and Fraïssé properties of Orlicz sequence spaces

Fuente: arXiv
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Main Authors: de Rancourt, Noé, Fakhoury, Micheline
Format: Preprint
Published: 2026
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author de Rancourt, Noé
Fakhoury, Micheline
author_facet de Rancourt, Noé
Fakhoury, Micheline
contents We provide an approximate version of a rigidity result by Randrianantoanina: for a large class of Orlicz sequence spaces, almost isometric embeddings almost preserve disjointness. In specific cases, we can even prove that such embeddings almost preserve basic vectors. As a consequence, we prove that some Orlicz sequences spaces are guarded Fraïssé but not $ω$-categorical; moreover, they do not contain copies of $\ell_2$ and their age is not closed. This answers a question of Cúth-de Rancourt-Doucha.
format Preprint
id arxiv_https___arxiv_org_abs_2604_02080
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Isometric rigidity and Fraïssé properties of Orlicz sequence spaces
de Rancourt, Noé
Fakhoury, Micheline
Functional Analysis
46B04 (Primary) 46B45, 46E30, 03C66, 03C35 (Secondary)
We provide an approximate version of a rigidity result by Randrianantoanina: for a large class of Orlicz sequence spaces, almost isometric embeddings almost preserve disjointness. In specific cases, we can even prove that such embeddings almost preserve basic vectors. As a consequence, we prove that some Orlicz sequences spaces are guarded Fraïssé but not $ω$-categorical; moreover, they do not contain copies of $\ell_2$ and their age is not closed. This answers a question of Cúth-de Rancourt-Doucha.
title Isometric rigidity and Fraïssé properties of Orlicz sequence spaces
topic Functional Analysis
46B04 (Primary) 46B45, 46E30, 03C66, 03C35 (Secondary)
url https://arxiv.org/abs/2604.02080