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Main Authors: Berger, Clemens, Funk, Jonathon
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2601.13301
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author Berger, Clemens
Funk, Jonathon
author_facet Berger, Clemens
Funk, Jonathon
contents We introduce locally involutive semigroups and embed them into the category of ordered groupoids. This embedding restricts to a correspondence between quasi-involutive semigroups and ordered groupoids with mediator, extending the classical ESN-correspondence between inverse semigroups and inductive groupoids. An important subcategory of locally involutive semigroups is formed by left involutive semigroups because the classifying topos of an inverse semigroup S is equivalent to the category of left involutive semigroups étale over S [4]. We recover this equivalence from a general adjointness and use the latter to determine when a left involutive semigroup étale over S is actually an involutive semigroup. Any left involutive semigroup étale over S embeds into an involutive S-algebra as we call it. The underlying semigroup of this algebra is involutive.
format Preprint
id arxiv_https___arxiv_org_abs_2601_13301
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Locally involutive semigroups
Berger, Clemens
Funk, Jonathon
Group Theory
Category Theory
Primary 20M10, 20M18, Secondary 18B40, 20M30
We introduce locally involutive semigroups and embed them into the category of ordered groupoids. This embedding restricts to a correspondence between quasi-involutive semigroups and ordered groupoids with mediator, extending the classical ESN-correspondence between inverse semigroups and inductive groupoids. An important subcategory of locally involutive semigroups is formed by left involutive semigroups because the classifying topos of an inverse semigroup S is equivalent to the category of left involutive semigroups étale over S [4]. We recover this equivalence from a general adjointness and use the latter to determine when a left involutive semigroup étale over S is actually an involutive semigroup. Any left involutive semigroup étale over S embeds into an involutive S-algebra as we call it. The underlying semigroup of this algebra is involutive.
title Locally involutive semigroups
topic Group Theory
Category Theory
Primary 20M10, 20M18, Secondary 18B40, 20M30
url https://arxiv.org/abs/2601.13301