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Main Authors: Nollet, Scott, Rao, A. P.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2501.05630
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author Nollet, Scott
Rao, A. P.
author_facet Nollet, Scott
Rao, A. P.
contents If $\mathcal E, \mathcal F$ are vector bundles of ranks $r-1,r$ on a smooth fourfold $X$ and $\mathcal{Hom}(\mathcal E,\mathcal F)$ is globally generated, it is well known that the general map $ϕ: \mathcal E \to \mathcal F$ is injective and drops rank along a smooth surface. Chang improved on this with a filtered Bertini theorem. We strengthen these results by proving variants in which (a) $\mathcal F$ is not a vector bundle and (b) $\mathcal{Hom}(\mathcal E,\mathcal F)$ is not globally generated. As an application, we give examples of even linkage classes of surfaces on $\mathbb P^4$ in which all integral surfaces are smoothable, including the linkage classes associated with the Horrocks-Mumford surface.
format Preprint
id arxiv_https___arxiv_org_abs_2501_05630
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Smoothing surfaces on fourfolds
Nollet, Scott
Rao, A. P.
Algebraic Geometry
14F06, 14J35, 14M07, 14M06
If $\mathcal E, \mathcal F$ are vector bundles of ranks $r-1,r$ on a smooth fourfold $X$ and $\mathcal{Hom}(\mathcal E,\mathcal F)$ is globally generated, it is well known that the general map $ϕ: \mathcal E \to \mathcal F$ is injective and drops rank along a smooth surface. Chang improved on this with a filtered Bertini theorem. We strengthen these results by proving variants in which (a) $\mathcal F$ is not a vector bundle and (b) $\mathcal{Hom}(\mathcal E,\mathcal F)$ is not globally generated. As an application, we give examples of even linkage classes of surfaces on $\mathbb P^4$ in which all integral surfaces are smoothable, including the linkage classes associated with the Horrocks-Mumford surface.
title Smoothing surfaces on fourfolds
topic Algebraic Geometry
14F06, 14J35, 14M07, 14M06
url https://arxiv.org/abs/2501.05630