The locally free locus of Quot schemes on $\mathbb{P}^1$

Fuente: arXiv
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Autori principali: Lin, Feiyang, Lysek, Theodore
Natura: Preprint
Pubblicazione: 2025
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author Lin, Feiyang
Lysek, Theodore
author_facet Lin, Feiyang
Lysek, Theodore
contents We characterize components of the locally free locus $\operatorname{Quot}^{n,d}_{\mathbb{P}^1}(\mathcal{O}(\vec{e}))^{\circ}$ of the Quot scheme associated to any vector bundle on $\mathbb{P}^1$. Specifically, we show that the components are in bijection with certain combinatorial objects which we call strongly stable pairs. Using our explicit understanding of the components, we prove that $\operatorname{Quot}^{n,d}_{\mathbb{P}^1}(\mathcal{O}(\vec{e}))^{\circ}$ is connected, and we give an explicit bound for when $\operatorname{Quot}^{n,d}_{\mathbb{P}^1}(\mathcal{O}(\vec{e}))^{\circ}$ is irreducible. The key ingredient is a combinatorial criterion for when a triple of vector bundles on $\mathbb{P}^1$ arises in a short exact sequence. As a consequence, we prove that in codimension $2$, all integral lattice points in the Boij-Söderberg cone are Betti diagrams of actual modules.
format Preprint
id arxiv_https___arxiv_org_abs_2512_13386
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The locally free locus of Quot schemes on $\mathbb{P}^1$
Lin, Feiyang
Lysek, Theodore
Algebraic Geometry
Commutative Algebra
14D20, 13D02
We characterize components of the locally free locus $\operatorname{Quot}^{n,d}_{\mathbb{P}^1}(\mathcal{O}(\vec{e}))^{\circ}$ of the Quot scheme associated to any vector bundle on $\mathbb{P}^1$. Specifically, we show that the components are in bijection with certain combinatorial objects which we call strongly stable pairs. Using our explicit understanding of the components, we prove that $\operatorname{Quot}^{n,d}_{\mathbb{P}^1}(\mathcal{O}(\vec{e}))^{\circ}$ is connected, and we give an explicit bound for when $\operatorname{Quot}^{n,d}_{\mathbb{P}^1}(\mathcal{O}(\vec{e}))^{\circ}$ is irreducible. The key ingredient is a combinatorial criterion for when a triple of vector bundles on $\mathbb{P}^1$ arises in a short exact sequence. As a consequence, we prove that in codimension $2$, all integral lattice points in the Boij-Söderberg cone are Betti diagrams of actual modules.
title The locally free locus of Quot schemes on $\mathbb{P}^1$
topic Algebraic Geometry
Commutative Algebra
14D20, 13D02
url https://arxiv.org/abs/2512.13386