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arXiv 2105.04775math.CTmath.AT
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单纯集的弱笛卡尔性质

Weak cartesian properties of simplicial sets

Carmen Constantin, Tobias Fritz, Paolo Perrone, Brandon Shapiro

AI总结:

本文定义单纯集的弱拉回型完备性条件,刻画其提升性质并给出基于 $Δ$ 中推出方形分解的检验判据,例子涵盖拟范畴、compositories、gleaves 及单子代数 bar 构造。

摘要:

许多特殊类别的单纯集,例如范畴或群胚的神经、Dyckerhoff 和 Kapranov 的 2-Segal 集,以及 Gálvez、Kock 和 Tonks 的(离散)分解空间,其特征在于将单纯范畴 $Δ$ 中的某些交换方形映为集合的拉回方形。我们引入这些性质的较弱类似物,称为完备性条件,它们要求将 $Δ$ 中的方形映为集合的弱拉回;弱拉回的定义与拉回方形类似,但诱导映射不具有唯一性。我们表明,其中一些完备性条件使单纯集获得相对于某些单纯子集的提升,这些子集最初在数据库设计理论中被引入。我们还利用 $Δ$ 中推出方形的分解结果,给出了检验这些性质的简化判据;我们完全刻画了这些推出方形以及 $Δ$ 中其他几类方形。具有完备性条件的单纯集例子包括拟范畴、Flori 和 Fritz 的许多 compositories 与 gleaves,以及某些类别单子的代数的 bar 构造。后者是我们的动机性例子。

英文摘要:

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.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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