Weak cartesian properties of simplicial sets

Many special classes of simplicial sets, such as the nerves of categories or groupoids, the 2-Segal sets of Dyckerhoff and Kapranov, and the (discrete) decomposition spaces of Gálvez, Kock, and Tonks, are characterized by the property of sending certain commuting squares in the simplex category Δ to...

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Main Authors: Constantin, C, Fritz, T, Perrone, P, Shapiro, BT
Format: Journal article
Language:English
Published: Springer 2023
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author Constantin, C
Fritz, T
Perrone, P
Shapiro, BT
author_facet Constantin, C
Fritz, T
Perrone, P
Shapiro, BT
author_sort Constantin, C
collection OXFORD
description Many special classes of simplicial sets, such as the nerves of categories or groupoids, the 2-Segal sets of Dyckerhoff and Kapranov, and the (discrete) decomposition spaces of Gálvez, Kock, and Tonks, are characterized by the property of sending certain commuting squares in the simplex category Δ to pullback squares of sets. We introduce weaker analogues of these properties called completeness conditions, which require squares in Δ to be sent to weak pullbacks of sets, defined similarly to pullback squares but without the uniqueness property of induced maps. We show that some of these completeness conditions provide a simplicial set with lifts against certain subsets of simplices first introduced in the theory of database design. We also provide reduced criteria for checking these properties using factorization results for pushouts squares in Δ , which we characterize completely, along with several other classes of squares in Δ . Examples of simplicial sets with completeness conditions include quasicategories, many of the compositories and gleaves of Flori and Fritz, and bar constructions for algebras of certain classes of monads. The latter is our motivating example.
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spelling oxford-uuid:07805bf9-e286-4633-95c5-7ee5603ef3e72024-11-11T08:52:29ZWeak cartesian properties of simplicial setsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:07805bf9-e286-4633-95c5-7ee5603ef3e7EnglishSymplectic ElementsSpringer2023Constantin, CFritz, TPerrone, PShapiro, BTMany special classes of simplicial sets, such as the nerves of categories or groupoids, the 2-Segal sets of Dyckerhoff and Kapranov, and the (discrete) decomposition spaces of Gálvez, Kock, and Tonks, are characterized by the property of sending certain commuting squares in the simplex category Δ to pullback squares of sets. We introduce weaker analogues of these properties called completeness conditions, which require squares in Δ to be sent to weak pullbacks of sets, defined similarly to pullback squares but without the uniqueness property of induced maps. We show that some of these completeness conditions provide a simplicial set with lifts against certain subsets of simplices first introduced in the theory of database design. We also provide reduced criteria for checking these properties using factorization results for pushouts squares in Δ , which we characterize completely, along with several other classes of squares in Δ . Examples of simplicial sets with completeness conditions include quasicategories, many of the compositories and gleaves of Flori and Fritz, and bar constructions for algebras of certain classes of monads. The latter is our motivating example.
spellingShingle Constantin, C
Fritz, T
Perrone, P
Shapiro, BT
Weak cartesian properties of simplicial sets
title Weak cartesian properties of simplicial sets
title_full Weak cartesian properties of simplicial sets
title_fullStr Weak cartesian properties of simplicial sets
title_full_unstemmed Weak cartesian properties of simplicial sets
title_short Weak cartesian properties of simplicial sets
title_sort weak cartesian properties of simplicial sets
work_keys_str_mv AT constantinc weakcartesianpropertiesofsimplicialsets
AT fritzt weakcartesianpropertiesofsimplicialsets
AT perronep weakcartesianpropertiesofsimplicialsets
AT shapirobt weakcartesianpropertiesofsimplicialsets