Ideally regular categories

Fuente: arXiv
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Main Authors: Mantovani, Sandra, Messora, Mariano
Format: Preprint
Published: 2025
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author Mantovani, Sandra
Messora, Mariano
author_facet Mantovani, Sandra
Messora, Mariano
contents In this note, we propose a generalisation of G. Janelidze's notion of an ideally exact category beyond the Barr exact setting. We define an ideally regular category as a regular, Bourn protomodular category with finite coproducts in which the unique morphism 0 -> 1 is effective for descent. As in the ideally exact case, ideally regular categories support a notion of ideal that classifies regular quotients. Moreover, they admit a characterisation in terms of monadicity over a homological category (rather than a semi-abelian one, as in the exact setting). Examples include Bourn protomodular quasivarieties of universal algebra in which 0 -> 1 is effective for descent (such as the category of torsion-free unital rings), all Bourn protomodular topological varieties with at least one constant (such as topological rings), and all semi-localisations of ideally exact categories.
format Preprint
id arxiv_https___arxiv_org_abs_2511_21913
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ideally regular categories
Mantovani, Sandra
Messora, Mariano
Category Theory
18E08, 18E13, 18C15, 08C15, 22A99
In this note, we propose a generalisation of G. Janelidze's notion of an ideally exact category beyond the Barr exact setting. We define an ideally regular category as a regular, Bourn protomodular category with finite coproducts in which the unique morphism 0 -> 1 is effective for descent. As in the ideally exact case, ideally regular categories support a notion of ideal that classifies regular quotients. Moreover, they admit a characterisation in terms of monadicity over a homological category (rather than a semi-abelian one, as in the exact setting). Examples include Bourn protomodular quasivarieties of universal algebra in which 0 -> 1 is effective for descent (such as the category of torsion-free unital rings), all Bourn protomodular topological varieties with at least one constant (such as topological rings), and all semi-localisations of ideally exact categories.
title Ideally regular categories
topic Category Theory
18E08, 18E13, 18C15, 08C15, 22A99
url https://arxiv.org/abs/2511.21913