The MMP singularities of GIT versus Baily-Borel compactifications for the ball quotient case

Fuente: arXiv
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Auteur principal: Shen, Dali
Format: Preprint
Publié: 2025
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author Shen, Dali
author_facet Shen, Dali
contents When the geometric invariant theory and the Baily-Borel theory both apply to a moduli space, the two resulting compactifications do not necessarily coincide. They usually differ by a birational transformation in terms of an arrangement, for which the general pattern was firstly described by Looijenga. In this paper, we compare the MMP singularities on both sides for the ball quotient case. We show that if the relevant arrangement is nonempty, the birational transformation from the GIT compactification to the Baily-Borel compactification turns non-log canonical singularities to log canonical singularities. We illustrate this with the moduli spaces of quartic curves, rational elliptic surfaces and cubic threefolds.
format Preprint
id arxiv_https___arxiv_org_abs_2509_24412
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The MMP singularities of GIT versus Baily-Borel compactifications for the ball quotient case
Shen, Dali
Algebraic Geometry
When the geometric invariant theory and the Baily-Borel theory both apply to a moduli space, the two resulting compactifications do not necessarily coincide. They usually differ by a birational transformation in terms of an arrangement, for which the general pattern was firstly described by Looijenga. In this paper, we compare the MMP singularities on both sides for the ball quotient case. We show that if the relevant arrangement is nonempty, the birational transformation from the GIT compactification to the Baily-Borel compactification turns non-log canonical singularities to log canonical singularities. We illustrate this with the moduli spaces of quartic curves, rational elliptic surfaces and cubic threefolds.
title The MMP singularities of GIT versus Baily-Borel compactifications for the ball quotient case
topic Algebraic Geometry
url https://arxiv.org/abs/2509.24412