Constructing monoidal structures on fibered categories via factorizations

Fuente: arXiv
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Auteur principal: Terenzi, Luca
Format: Preprint
Publié: 2024
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author Terenzi, Luca
author_facet Terenzi, Luca
contents Let $\mathcal{S}$ be a small category, and suppose that we are given two (non-full) subcategories $\mathcal{S}^{sm}$ and $\mathcal{S}^{cl}$ that generate all morphisms of $\mathcal{S}$ under composition in the same way as morphisms of quasi-projective algebraic varieties are generated by smooth morphisms and closed immersions. We show that a monoidal structure on a given $\mathcal{S}$-fibered category is completely determined by its restrictions to $\mathcal{S}^{sm}$ and $\mathcal{S}^{cl}$; in fact, any such pair of monoidal structures satisfying a natural coherence condition uniquely determines a monoidal structure over $\mathcal{S}$. The same principle applies to morphisms of $\mathcal{S}$-fibered categories and monoidality thereof. Under further assumptions on the subcategories $\mathcal{S}^{sm}$ and $\mathcal{S}^{cl}$, and with suitable restrictions on the $\mathcal{S}$-fibered categories and morphisms involved, we provide a variant of the above factorization method in which inverse images under closed immersion are partially replaced by the corresponding direct images: the latter variant is more adapted to the setting of perverse sheaves.
format Preprint
id arxiv_https___arxiv_org_abs_2401_13489
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Constructing monoidal structures on fibered categories via factorizations
Terenzi, Luca
Category Theory
Algebraic Geometry
18D30, 18M05
Let $\mathcal{S}$ be a small category, and suppose that we are given two (non-full) subcategories $\mathcal{S}^{sm}$ and $\mathcal{S}^{cl}$ that generate all morphisms of $\mathcal{S}$ under composition in the same way as morphisms of quasi-projective algebraic varieties are generated by smooth morphisms and closed immersions. We show that a monoidal structure on a given $\mathcal{S}$-fibered category is completely determined by its restrictions to $\mathcal{S}^{sm}$ and $\mathcal{S}^{cl}$; in fact, any such pair of monoidal structures satisfying a natural coherence condition uniquely determines a monoidal structure over $\mathcal{S}$. The same principle applies to morphisms of $\mathcal{S}$-fibered categories and monoidality thereof. Under further assumptions on the subcategories $\mathcal{S}^{sm}$ and $\mathcal{S}^{cl}$, and with suitable restrictions on the $\mathcal{S}$-fibered categories and morphisms involved, we provide a variant of the above factorization method in which inverse images under closed immersion are partially replaced by the corresponding direct images: the latter variant is more adapted to the setting of perverse sheaves.
title Constructing monoidal structures on fibered categories via factorizations
topic Category Theory
Algebraic Geometry
18D30, 18M05
url https://arxiv.org/abs/2401.13489