Inner automorphisms as 2-cells

Fuente: arXiv
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Main Authors: Hofstra, Pieter, Karvonen, Martti
Format: Preprint
Published: 2024
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author Hofstra, Pieter
Karvonen, Martti
author_facet Hofstra, Pieter
Karvonen, Martti
contents Abstract inner automorphisms can be used to promote any category into a 2-category, and we study two-dimensional limits and colimits in the resulting 2-categories. Existing connected colimits and limits in the starting category become two-dimensional colimits and limits under fairly general conditions. Under the same conditions, colimits in the underlying category can be used to build many notable two-dimensional colimits such as coequifiers and coinserters. In contrast, disconnected colimits or genuinely 2-categorical limits such as inserters and equifiers and cotensors cannot exist unless no nontrivial abstract inner automorphisms exist and the resulting 2-category is locally discrete. We also study briefly when an ordinary functor can be extended to a 2-functor between the resulting 2-categories.
format Preprint
id arxiv_https___arxiv_org_abs_2406_13647
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Inner automorphisms as 2-cells
Hofstra, Pieter
Karvonen, Martti
Category Theory
18A30, 18G45, 18N10
Abstract inner automorphisms can be used to promote any category into a 2-category, and we study two-dimensional limits and colimits in the resulting 2-categories. Existing connected colimits and limits in the starting category become two-dimensional colimits and limits under fairly general conditions. Under the same conditions, colimits in the underlying category can be used to build many notable two-dimensional colimits such as coequifiers and coinserters. In contrast, disconnected colimits or genuinely 2-categorical limits such as inserters and equifiers and cotensors cannot exist unless no nontrivial abstract inner automorphisms exist and the resulting 2-category is locally discrete. We also study briefly when an ordinary functor can be extended to a 2-functor between the resulting 2-categories.
title Inner automorphisms as 2-cells
topic Category Theory
18A30, 18G45, 18N10
url https://arxiv.org/abs/2406.13647