Proper morphisms of $\infty$-topoi

Fuente: arXiv
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Autores principales: Martini, Louis, Wolf, Sebastian
Formato: Preprint
Publicado: 2023
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author Martini, Louis
Wolf, Sebastian
author_facet Martini, Louis
Wolf, Sebastian
contents We characterise proper morphisms of $\infty$-topoi in terms of a relativised notion of compactness: we show that a geometric morphism of $\infty$-topoi is proper if and only if it commutes with colimits indexed by filtered internal $\infty$-categories in the target. In particular, our result implies that for any $\infty$-topos, the global sections functor is proper if and only if it preserves filtered colimits. As an application, we show that every proper and separated map of topological spaces gives rise to a proper morphism between the associated sheaf $\infty$-topoi, generalising a result of Lurie. Along the way, we develop some aspects of the theory of localic higher topoi internal to an $\infty$-topos, which might be of independent interest.
format Preprint
id arxiv_https___arxiv_org_abs_2311_08051
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Proper morphisms of $\infty$-topoi
Martini, Louis
Wolf, Sebastian
Category Theory
Algebraic Topology
We characterise proper morphisms of $\infty$-topoi in terms of a relativised notion of compactness: we show that a geometric morphism of $\infty$-topoi is proper if and only if it commutes with colimits indexed by filtered internal $\infty$-categories in the target. In particular, our result implies that for any $\infty$-topos, the global sections functor is proper if and only if it preserves filtered colimits. As an application, we show that every proper and separated map of topological spaces gives rise to a proper morphism between the associated sheaf $\infty$-topoi, generalising a result of Lurie. Along the way, we develop some aspects of the theory of localic higher topoi internal to an $\infty$-topos, which might be of independent interest.
title Proper morphisms of $\infty$-topoi
topic Category Theory
Algebraic Topology
url https://arxiv.org/abs/2311.08051