Sketches and Classifying Logoi

Fuente: arXiv
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Autori principali: Di Liberti, Ivan, Lobbia, Gabriele
Natura: Preprint
Pubblicazione: 2024
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author Di Liberti, Ivan
Lobbia, Gabriele
author_facet Di Liberti, Ivan
Lobbia, Gabriele
contents Inspired by the theory of classifying topoi for geometric theories, we define rounded sketches and logoi and provide the notion of classifying logos for a rounded sketch. Rounded sketches can be used to axiomatise all the known fragments of infinitary first order logic in $\mathbf{L}_{\infty,\infty}$, in a spectrum ranging from weaker than finitary algebraic to stronger than $λ$-geometric for $λ$ a regular cardinal. We show that every rounded sketch has an associated classifying logos, having similar properties to the classifying topos of a geometric theory. This amounts to a Diaconescu-type result for rounded sketches and (Morita small) logoi, which generalises the one for classifying topoi.
format Preprint
id arxiv_https___arxiv_org_abs_2403_09264
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Sketches and Classifying Logoi
Di Liberti, Ivan
Lobbia, Gabriele
Category Theory
Logic
18A15, 03C75, 18C10, 18B25, 18C30, 18C10
Inspired by the theory of classifying topoi for geometric theories, we define rounded sketches and logoi and provide the notion of classifying logos for a rounded sketch. Rounded sketches can be used to axiomatise all the known fragments of infinitary first order logic in $\mathbf{L}_{\infty,\infty}$, in a spectrum ranging from weaker than finitary algebraic to stronger than $λ$-geometric for $λ$ a regular cardinal. We show that every rounded sketch has an associated classifying logos, having similar properties to the classifying topos of a geometric theory. This amounts to a Diaconescu-type result for rounded sketches and (Morita small) logoi, which generalises the one for classifying topoi.
title Sketches and Classifying Logoi
topic Category Theory
Logic
18A15, 03C75, 18C10, 18B25, 18C30, 18C10
url https://arxiv.org/abs/2403.09264