527 elliptic fibrations on Enriques surfaces

Fuente: arXiv
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Autori principali: Brandhorst, Simon, González-Alonso, Víctor
Natura: Preprint
Pubblicazione: 2024
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author Brandhorst, Simon
González-Alonso, Víctor
author_facet Brandhorst, Simon
González-Alonso, Víctor
contents Barth and Peters showed that a general complex Enriques surface has exactly 527 isomorphism classes of elliptic fibrations. We show that every Enriques surface has precisely 527 isomorphism classes of elliptic fibrations when counted with the appropriate multiplicity. Their reducible singular fibers and the multiplicities can be calculated explicitly. The same statements hold over any algebraically closed field of characteristic not two. To explain these results, we construct a moduli space of complex elliptic Enriques surfaces and study the ramification behavior of the forgetful map to the moduli space of unpolarized Enriques surfaces. Curiously, the ramification indices of a similar map compute the hyperbolic volume of the rational polyhedral fundamental domain appearing in the Morrison-Kawamata cone conjecture.
format Preprint
id arxiv_https___arxiv_org_abs_2408_00306
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle 527 elliptic fibrations on Enriques surfaces
Brandhorst, Simon
González-Alonso, Víctor
Algebraic Geometry
14J27, 14J28, 32G13
Barth and Peters showed that a general complex Enriques surface has exactly 527 isomorphism classes of elliptic fibrations. We show that every Enriques surface has precisely 527 isomorphism classes of elliptic fibrations when counted with the appropriate multiplicity. Their reducible singular fibers and the multiplicities can be calculated explicitly. The same statements hold over any algebraically closed field of characteristic not two. To explain these results, we construct a moduli space of complex elliptic Enriques surfaces and study the ramification behavior of the forgetful map to the moduli space of unpolarized Enriques surfaces. Curiously, the ramification indices of a similar map compute the hyperbolic volume of the rational polyhedral fundamental domain appearing in the Morrison-Kawamata cone conjecture.
title 527 elliptic fibrations on Enriques surfaces
topic Algebraic Geometry
14J27, 14J28, 32G13
url https://arxiv.org/abs/2408.00306