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Bibliographic Details
Main Author: Leinster, Tom
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2508.20555
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author Leinster, Tom
author_facet Leinster, Tom
contents Many types of categorical structure obey the following principle: the natural notion of equivalence is generated, as an equivalence relation, by identifying $A$ with $B$ when there exists a strictly structure-preserving map $A \to B$ that is genuinely (not just essentially) surjective in each dimension and faithful in the top dimension. We prove this principle for four types of structure: categories, monoidal categories, bicategories and double categories. The last of these theorems suggests that the right notion of equivalence between double categories is Campbell's gregarious double equivalence, a conclusion also reached for different reasons in recent work of Moser, Sarazola and Verdugo.
format Preprint
id arxiv_https___arxiv_org_abs_2508_20555
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Equivalence via surjections
Leinster, Tom
Category Theory
Many types of categorical structure obey the following principle: the natural notion of equivalence is generated, as an equivalence relation, by identifying $A$ with $B$ when there exists a strictly structure-preserving map $A \to B$ that is genuinely (not just essentially) surjective in each dimension and faithful in the top dimension. We prove this principle for four types of structure: categories, monoidal categories, bicategories and double categories. The last of these theorems suggests that the right notion of equivalence between double categories is Campbell's gregarious double equivalence, a conclusion also reached for different reasons in recent work of Moser, Sarazola and Verdugo.
title Equivalence via surjections
topic Category Theory
url https://arxiv.org/abs/2508.20555