Birational Geometry of sextic del Pezzo surfaces

Fuente: arXiv
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Main Authors: Kurz, Elias, Yasinsky, Egor
Format: Preprint
Published: 2025
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author Kurz, Elias
Yasinsky, Egor
author_facet Kurz, Elias
Yasinsky, Egor
contents We study the biregular and birational geometry of degree 6 del Pezzo surfaces with Picard number 1, defined over an arbitrary perfect field. Using Galois cohomology techniques, we obtain an explicit description of cocycles for such surfaces and describe the Severi-Brauer varieties associated with them, recovering the biregular classification of sextic del Pezzo surfaces. We then compute the automorphism groups of such surfaces, describe their closed points in general position and investigate the structure of Sarkisov links at such points and the corresponding birational models, answering a question of M. Rost. Using this description, we show that degree 6 del Pezzo surfaces are the only solid surfaces that admit infinite pliability. We also find a system of generators and relations for the groups of birational transformations of such surfaces and use it to construct nontrivial quotients of these groups, including free groups on uncountable sets.
format Preprint
id arxiv_https___arxiv_org_abs_2507_21737
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Birational Geometry of sextic del Pezzo surfaces
Kurz, Elias
Yasinsky, Egor
Algebraic Geometry
12G05, 14E07, 14E05, 14J26, 14J50, 14E30, 14J45, 14M22, 20F05
We study the biregular and birational geometry of degree 6 del Pezzo surfaces with Picard number 1, defined over an arbitrary perfect field. Using Galois cohomology techniques, we obtain an explicit description of cocycles for such surfaces and describe the Severi-Brauer varieties associated with them, recovering the biregular classification of sextic del Pezzo surfaces. We then compute the automorphism groups of such surfaces, describe their closed points in general position and investigate the structure of Sarkisov links at such points and the corresponding birational models, answering a question of M. Rost. Using this description, we show that degree 6 del Pezzo surfaces are the only solid surfaces that admit infinite pliability. We also find a system of generators and relations for the groups of birational transformations of such surfaces and use it to construct nontrivial quotients of these groups, including free groups on uncountable sets.
title Birational Geometry of sextic del Pezzo surfaces
topic Algebraic Geometry
12G05, 14E07, 14E05, 14J26, 14J50, 14E30, 14J45, 14M22, 20F05
url https://arxiv.org/abs/2507.21737