Birational geometry of sextic double solids with a compound $A_n$ singularity

Fuente: arXiv
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Auteur principal: Paemurru, Erik
Format: Preprint
Publié: 2021
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author Paemurru, Erik
author_facet Paemurru, Erik
contents Sextic double solids, double covers of $\mathbb P^3$ branched along a sextic surface, are the lowest degree Gorenstein Fano 3-folds, hence are expected to behave very rigidly in terms of birational geometry. Smooth sextic double solids, and those which are $\mathbb Q$-factorial with ordinary double points, are known to be birationally rigid. In this article, we study sextic double solids with an isolated compound $A_n$ singularity. We prove a sharp bound $n \leq 8$, describe models for each $n$ explicitly and prove that sextic double solids with $n > 3$ are birationally non-rigid.
format Preprint
id arxiv_https___arxiv_org_abs_2101_00501
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Birational geometry of sextic double solids with a compound $A_n$ singularity
Paemurru, Erik
Algebraic Geometry
14J45 (Primary) 14J30, 14J17, 14E30, 14E05 (Secondary)
Sextic double solids, double covers of $\mathbb P^3$ branched along a sextic surface, are the lowest degree Gorenstein Fano 3-folds, hence are expected to behave very rigidly in terms of birational geometry. Smooth sextic double solids, and those which are $\mathbb Q$-factorial with ordinary double points, are known to be birationally rigid. In this article, we study sextic double solids with an isolated compound $A_n$ singularity. We prove a sharp bound $n \leq 8$, describe models for each $n$ explicitly and prove that sextic double solids with $n > 3$ are birationally non-rigid.
title Birational geometry of sextic double solids with a compound $A_n$ singularity
topic Algebraic Geometry
14J45 (Primary) 14J30, 14J17, 14E30, 14E05 (Secondary)
url https://arxiv.org/abs/2101.00501