How protomodular is your favourite category?
Abstract
In this work we investigate a relative notion of protomodularity. We say that a finitely complete category C satisfies the \defn{ℳ-version of protomodularity} when the change-of-base functors (concerning the fibration of points) are conservative with respect to a class of morphisms ℳ of C. If ℳ is the class of all morphisms or the class of all monomorphisms of C, then this notion is precisely that of an ``ordinary'' protomodular category. We analyse what conditions the class ℳ should have to obtain the relative ℳ-versions of some well-known properties of protomodular categories, such as the Split Short Five Lemma (when C is also pointed) and their relation with Mal'tsev categories. We also give diverse examples of categories satisfying the ℳ-version of protomodularity for different choices of ℳ.
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BibTeX
@misc{clementino2026protomodular,
title = {{How protomodular is your favourite category?}},
author = {Maria Manuel Clementino and Diana Rodelo},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.09739},
eprint = {2610.09739},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.09739},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - How protomodular is your favourite category?
AU - Maria Manuel Clementino
AU - Diana Rodelo
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.09739
UR - https://arxiv.org/abs/2610.09739
AB - In this work we investigate a relative notion of protomodularity. We say that a finitely complete category C satisfies the \defn{ℳ-version of protomodularity} when the change-of-base functors (concerning the fibration of points) are conservative with respect to a class of morphisms ℳ of C. If ℳ is the class of all morphisms or the class of all monomorphisms of C, then this notion is precisely that of an ``ordinary'' protomodular category. We analyse what conditions the class ℳ should have to obtain the relative ℳ-versions of some well-known properties of protomodular categories, such as the Split Short Five Lemma (when C is also pointed) and their relation with Mal'tsev categories. We also give diverse examples of categories satisfying the ℳ-version of protomodularity for different choices of ℳ.
ER -