Cauchy Completeness, Lax Epimorphisms and Effective Descent for Split Fibrations
| Autor: | Nunes, Fernando Lucatelli, Prezado, Rui, Sousa, Lurdes |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Bull. Belg. Math. Soc. Simon Stevin 30(1): 130-139 (july 2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.36045/j.bbms.221021 |
| Popis: | For any suitable base category $\mathcal{V} $, we find that $\mathcal{V} $-fully faithful lax epimorphisms in $\mathcal{V} $-$\mathsf{Cat} $ are precisely those $\mathcal{V}$-functors $F \colon \mathcal{A} \to \mathcal{B}$ whose induced $\mathcal{V} $-functors $\mathsf{Cauchy} F \colon \mathsf{Cauchy} \mathcal{A} \to \mathsf{Cauchy} \mathcal{B} $ between the Cauchy completions are equivalences. For the case $\mathcal{V} = \mathsf{Set} $, this is equivalent to requiring that the induced functor $\mathsf{CAT} \left( F,\mathsf{Cat}\right) $ between the categories of split (op)fibrations is an equivalence. By reducing the study of effective descent functors with respect to the indexed category of split (op)fibrations $\mathcal{F}$ to the study of the codescent factorization, we find that these observations on fully faithful lax epimorphisms provide us with a characterization of (effective) $\mathcal{F}$-descent morphisms in the category of small categories $\mathcal{Cat}$; namely, we find that they are precisely the (effective) descent morphisms with respect to the indexed categories of discrete opfibrations -- previously studied by Sobral. We include some comments on the Beck-Chevalley condition and future work. Comment: 8 pages, revised version, 11-01-2023 |
| Databáze: | arXiv |
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