Pushouts of Dwyer maps are $(\infty,1)$-categorical

Fuente: arXiv
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Main Authors: Hackney, Philip, Ozornova, Viktoriya, Riehl, Emily, Rovelli, Martina
Format: Preprint
Published: 2022
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author Hackney, Philip
Ozornova, Viktoriya
Riehl, Emily
Rovelli, Martina
author_facet Hackney, Philip
Ozornova, Viktoriya
Riehl, Emily
Rovelli, Martina
contents The inclusion of 1-categories into $(\infty,1)$-categories fails to preserve colimits in general, and pushouts in particular. In this note, we observe that if one functor in a span of categories belongs to a certain previously-identified class of functors, then the 1-categorical pushout is preserved under this inclusion. Dwyer maps, a kind of neighborhood deformation retract of categories, were used by Thomason in the construction of his model structure on 1-categories. Thomason previously observed that the nerves of such pushouts have the correct weak homotopy type. We refine this result and show that the weak homotopical equivalence is a weak categorical equivalence. We also identify a more general class of functors along which 1-categorical pushouts are $(\infty,1)$-categorical.
format Preprint
id arxiv_https___arxiv_org_abs_2205_02353
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Pushouts of Dwyer maps are $(\infty,1)$-categorical
Hackney, Philip
Ozornova, Viktoriya
Riehl, Emily
Rovelli, Martina
Algebraic Topology
Category Theory
18N60, 55U35
The inclusion of 1-categories into $(\infty,1)$-categories fails to preserve colimits in general, and pushouts in particular. In this note, we observe that if one functor in a span of categories belongs to a certain previously-identified class of functors, then the 1-categorical pushout is preserved under this inclusion. Dwyer maps, a kind of neighborhood deformation retract of categories, were used by Thomason in the construction of his model structure on 1-categories. Thomason previously observed that the nerves of such pushouts have the correct weak homotopy type. We refine this result and show that the weak homotopical equivalence is a weak categorical equivalence. We also identify a more general class of functors along which 1-categorical pushouts are $(\infty,1)$-categorical.
title Pushouts of Dwyer maps are $(\infty,1)$-categorical
topic Algebraic Topology
Category Theory
18N60, 55U35
url https://arxiv.org/abs/2205.02353