The birational geometry of GIT quotients

Fuente: arXiv
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Hauptverfasser: Dervan, Ruadhaí, Reboulet, Rémi
Format: Preprint
Veröffentlicht: 2023
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author Dervan, Ruadhaí
Reboulet, Rémi
author_facet Dervan, Ruadhaí
Reboulet, Rémi
contents Geometric Invariant Theory (GIT) produces quotients of algebraic varieties by reductive groups. If the variety is projective, this quotient depends on a choice of polarisation; by work of Dolgachev-Hu and Thaddeus, it is known that two quotients of the same variety using different polarisations are related by birational transformations. Only finitely many birational varieties arise in this way: variation of GIT fails to capture the entirety of the birational geometry of GIT quotients. We construct a space parametrising all possible GIT quotients of all birational models of the variety in a simple and natural way, which captures the entirety of the birational geometry of GIT quotients in a precise sense. It yields in particular a compactification of a birational analogue of the set of stable orbits of the variety.
format Preprint
id arxiv_https___arxiv_org_abs_2301_09227
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The birational geometry of GIT quotients
Dervan, Ruadhaí
Reboulet, Rémi
Algebraic Geometry
Geometric Invariant Theory (GIT) produces quotients of algebraic varieties by reductive groups. If the variety is projective, this quotient depends on a choice of polarisation; by work of Dolgachev-Hu and Thaddeus, it is known that two quotients of the same variety using different polarisations are related by birational transformations. Only finitely many birational varieties arise in this way: variation of GIT fails to capture the entirety of the birational geometry of GIT quotients. We construct a space parametrising all possible GIT quotients of all birational models of the variety in a simple and natural way, which captures the entirety of the birational geometry of GIT quotients in a precise sense. It yields in particular a compactification of a birational analogue of the set of stable orbits of the variety.
title The birational geometry of GIT quotients
topic Algebraic Geometry
url https://arxiv.org/abs/2301.09227