Classification of Horikawa surfaces with T-singularities

Fuente: arXiv
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Auteurs principaux: Monreal, Vicente, Negrete, Jaime, Urzúa, Giancarlo
Format: Preprint
Publié: 2024
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author Monreal, Vicente
Negrete, Jaime
Urzúa, Giancarlo
author_facet Monreal, Vicente
Negrete, Jaime
Urzúa, Giancarlo
contents We classify all projective surfaces with only T-singularities, ample canonical class, and $K^2=2p_g-4$. In this way, we identify all surfaces, smoothable or not, with only T-singularities in the Kollár--Shepherd-Barron--Alexeev (KSBA) moduli space of Horikawa surfaces. We also prove that they are not smoothable when $p_g \geq 10$, except for the Lee-Park (Fintushel-Stern) examples, which we show to have only one deformation type unless $p_g=6$ (in which case they have two). This demonstrates that the challenging Horikawa problem cannot be addressed through complex T-degenerations. We propose new questions regarding diffeomorphism types based on our classification. Furthermore, the techniques developed in this paper enable us to classify all KSBA surfaces with only T-singularities and $K^2\leq 2p_g-3$, for example, quintic surfaces and I-surfaces.
format Preprint
id arxiv_https___arxiv_org_abs_2410_02943
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Classification of Horikawa surfaces with T-singularities
Monreal, Vicente
Negrete, Jaime
Urzúa, Giancarlo
Algebraic Geometry
Differential Geometry
Geometric Topology
Symplectic Geometry
We classify all projective surfaces with only T-singularities, ample canonical class, and $K^2=2p_g-4$. In this way, we identify all surfaces, smoothable or not, with only T-singularities in the Kollár--Shepherd-Barron--Alexeev (KSBA) moduli space of Horikawa surfaces. We also prove that they are not smoothable when $p_g \geq 10$, except for the Lee-Park (Fintushel-Stern) examples, which we show to have only one deformation type unless $p_g=6$ (in which case they have two). This demonstrates that the challenging Horikawa problem cannot be addressed through complex T-degenerations. We propose new questions regarding diffeomorphism types based on our classification. Furthermore, the techniques developed in this paper enable us to classify all KSBA surfaces with only T-singularities and $K^2\leq 2p_g-3$, for example, quintic surfaces and I-surfaces.
title Classification of Horikawa surfaces with T-singularities
topic Algebraic Geometry
Differential Geometry
Geometric Topology
Symplectic Geometry
url https://arxiv.org/abs/2410.02943