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Extensivity relative to a bifunctor

Thesis (PhD)--Stellenbosch University, 2026.

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Bibliographic Details
Main Author: Theart, Emma
Other Authors: Hoefnagel, Michael
Format: Thesis
Language:English
Published: Stellenbosch : Stellenbosch University 2026
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access_status_str Open Access
author Theart, Emma
author2 Hoefnagel, Michael
author_browse Hoefnagel, Michael
Theart, Emma
author_facet Hoefnagel, Michael
Theart, Emma
author_sort Theart, Emma
collection Thesis
dc_rights_str_mv Stellenbosch University
description Thesis (PhD)--Stellenbosch University, 2026.
format Thesis
id oai:scholar.sun.ac.za:10019.1/135773
institution Stellenbosch University (South Africa)
language English
last_indexed 2026-06-10T12:46:49.940Z
license_str Other — see source repository
provenance_str_mv Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository
publishDate 2026
publishDateRange 2026
publishDateSort 2026
publisher Stellenbosch : Stellenbosch University
publisherStr Stellenbosch : Stellenbosch University
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source_str SUNScholar — Stellenbosch University Repository
spelling oai:scholar.sun.ac.za:10019.1/135773 Extensivity relative to a bifunctor Theart, Emma Hoefnagel, Michael Stellenbosch University. Faculty of Science. Dept. of Mathematical Sciences. Thesis (PhD)--Stellenbosch University, 2026. Theart, E. 2026. Extensivity relative to a bifunctor. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/e71456b9-3ba6-4e13-8155-80d6d08eee65 Extensive categories capture a fundamental feature of the category of sets: their coproducts are both disjoint and universal. Two equivalent formulations of extensive categories provide two distinct perspectives on the notion. The first is as a property of functors, and the second as a property of morphisms in the category. This thesis explores both perspectives. The morphism-focused viewpoint is captured through extensive morphisms, which allow one to study extensivity in categories that are not themselves extensive. From the functorial viewpoint, we introduce near-sums, functorial replacements for coproducts in categories lacking them. Near-sums provide a natural setting for extending the theory of extensive categories, capturing key features thereof, such as disjointness and universality. Doctoral 2026-04-10T06:41:30Z 2026-04-10T06:41:30Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/135773 en Stellenbosch University 112 pages application/pdf Stellenbosch : Stellenbosch University
spellingShingle Theart, Emma
Extensivity relative to a bifunctor
title Extensivity relative to a bifunctor
title_full Extensivity relative to a bifunctor
title_fullStr Extensivity relative to a bifunctor
title_full_unstemmed Extensivity relative to a bifunctor
title_short Extensivity relative to a bifunctor
title_sort extensivity relative to a bifunctor
url https://scholar.sun.ac.za/handle/10019.1/135773
work_keys_str_mv AT theartemma extensivityrelativetoabifunctor