Quintic del Pezzo threefolds in positive and mixed characteristic

Fuente: arXiv
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Auteurs principaux: Ito, Tetsushi, Kanemitsu, Akihiro, Takamatsu, Teppei, Tanaka, Yuuji
Format: Preprint
Publié: 2025
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_version_ 1866909912892702720
author Ito, Tetsushi
Kanemitsu, Akihiro
Takamatsu, Teppei
Tanaka, Yuuji
author_facet Ito, Tetsushi
Kanemitsu, Akihiro
Takamatsu, Teppei
Tanaka, Yuuji
contents We show that smooth quintic del Pezzo threefolds over arbitrary base schemes are classified by non-degenerate ternary symmetric bilinear forms. Then we describe the automorphism group schemes, the Hilbert schemes of lines and the orbit structures of quintic del Pezzo threefolds, and we find several new phenomena in characteristic two. As arithmetic applications, we prove a refinement of the Shafarevich conjecture, and prove that there are exactly two isomorphism classes of quintic del Pezzo threefolds over the ring of rational integers.
format Preprint
id arxiv_https___arxiv_org_abs_2506_15086
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quintic del Pezzo threefolds in positive and mixed characteristic
Ito, Tetsushi
Kanemitsu, Akihiro
Takamatsu, Teppei
Tanaka, Yuuji
Algebraic Geometry
14J45, 14G17, 11G35
We show that smooth quintic del Pezzo threefolds over arbitrary base schemes are classified by non-degenerate ternary symmetric bilinear forms. Then we describe the automorphism group schemes, the Hilbert schemes of lines and the orbit structures of quintic del Pezzo threefolds, and we find several new phenomena in characteristic two. As arithmetic applications, we prove a refinement of the Shafarevich conjecture, and prove that there are exactly two isomorphism classes of quintic del Pezzo threefolds over the ring of rational integers.
title Quintic del Pezzo threefolds in positive and mixed characteristic
topic Algebraic Geometry
14J45, 14G17, 11G35
url https://arxiv.org/abs/2506.15086