Pre-Galois categories and Fraïssé's theorem

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Hauptverfasser: Harman, Nate, Snowden, Andrew
Format: Preprint
Veröffentlicht: 2023
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author Harman, Nate
Snowden, Andrew
author_facet Harman, Nate
Snowden, Andrew
contents Galois categories can be viewed as the combinatorial analog of Tannakian categories. We introduce the notion of pre-Galois category, which can be viewed as the combinatorial analog of pre-Tannakian categories. Given an oligomorphic group $G$, the category $\mathbf{S}(G)$ of finitary smooth $G$-sets is pre-Galois. Our main theorem (approximately) says that these examples are exhaustive; this result is, in a sense, a reformulation of Fraïssé's theorem. We also introduce a more general class of B-categories, and give some examples of B-categories that are not pre-Galois using permutation classes. This work is motivated by certain applications to pre-Tannakian categories.
format Preprint
id arxiv_https___arxiv_org_abs_2301_13784
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Pre-Galois categories and Fraïssé's theorem
Harman, Nate
Snowden, Andrew
Representation Theory
Category Theory
Galois categories can be viewed as the combinatorial analog of Tannakian categories. We introduce the notion of pre-Galois category, which can be viewed as the combinatorial analog of pre-Tannakian categories. Given an oligomorphic group $G$, the category $\mathbf{S}(G)$ of finitary smooth $G$-sets is pre-Galois. Our main theorem (approximately) says that these examples are exhaustive; this result is, in a sense, a reformulation of Fraïssé's theorem. We also introduce a more general class of B-categories, and give some examples of B-categories that are not pre-Galois using permutation classes. This work is motivated by certain applications to pre-Tannakian categories.
title Pre-Galois categories and Fraïssé's theorem
topic Representation Theory
Category Theory
url https://arxiv.org/abs/2301.13784