The Frobenius equivalence and Beck-Chevalley condition for Algebraic Weak Factorisation Systems

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Hauptverfasser: van Woerkom, Wijnand, Berg, Benno van den
Format: Preprint
Veröffentlicht: 2024
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_version_ 1866914767951626240
author van Woerkom, Wijnand
Berg, Benno van den
author_facet van Woerkom, Wijnand
Berg, Benno van den
contents If a locally cartesian closed category carries a weak factorisation system, then the left maps are stable under pullback along right maps if and only if the right maps are closed under pushforward along right maps. We refer to this statement as the Frobenius equivalence and in this paper we state and prove an analogical statement for algebraic weak factorisation systems. These algebraic weak factorisation systems are an explicit variant of the more traditional weak factorisation systems in that the factorisation and the lifts are part of the structure of an algebraic weak factorisation system and are not merely required to exist. Our work has been motivated by the categorical semantics of type theory, where the Frobenius equivalence provides a useful tool for constructing dependent function types. We illustrate our ideas using split fibrations of groupoids, which are the backbone of the groupoid model of Hofmann and Streicher.
format Preprint
id arxiv_https___arxiv_org_abs_2404_15443
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Frobenius equivalence and Beck-Chevalley condition for Algebraic Weak Factorisation Systems
van Woerkom, Wijnand
Berg, Benno van den
Category Theory
Logic
18A32, 18N10, 03B38
If a locally cartesian closed category carries a weak factorisation system, then the left maps are stable under pullback along right maps if and only if the right maps are closed under pushforward along right maps. We refer to this statement as the Frobenius equivalence and in this paper we state and prove an analogical statement for algebraic weak factorisation systems. These algebraic weak factorisation systems are an explicit variant of the more traditional weak factorisation systems in that the factorisation and the lifts are part of the structure of an algebraic weak factorisation system and are not merely required to exist. Our work has been motivated by the categorical semantics of type theory, where the Frobenius equivalence provides a useful tool for constructing dependent function types. We illustrate our ideas using split fibrations of groupoids, which are the backbone of the groupoid model of Hofmann and Streicher.
title The Frobenius equivalence and Beck-Chevalley condition for Algebraic Weak Factorisation Systems
topic Category Theory
Logic
18A32, 18N10, 03B38
url https://arxiv.org/abs/2404.15443