Semistable reductions and minimalities of invariants for group scheme actions on projective schemes

Fuente: arXiv
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Main Authors: Gotou, Rin, Okuyama, Yûsuke
Format: Preprint
Published: 2026
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author Gotou, Rin
Okuyama, Yûsuke
author_facet Gotou, Rin
Okuyama, Yûsuke
contents Let $K$ be an algebraically closed and complete non-archimedean and non-trivially valued field, and let $G$ be a reductive group scheme acting on a flat projective scheme $X$ defined over the base ring of $K$-integers. For every $K$-point $x$ in $X$, we introduce the minimal invariant locus $\operatorname{MinInvLoc}_x$ and the semistable reduction translation locus $\operatorname{SSRL}_x$ in the translation space $\operatorname{BT}_G(K)$ associated with $G_K$, which is a variant of Bruhat-Tits building, and establish not only the coincidence of those loci but, under a mild completeness assumption, also their non-emptiness. In the dynamical setting which has been studied by Szpiro--Tepper--Williams and Rumely, the coincidence result is already new in higher dimensions, and the non-emptiness result includes Rumely's $1$-dimensional result at least in the spherical complete case.
format Preprint
id arxiv_https___arxiv_org_abs_2604_25659
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Semistable reductions and minimalities of invariants for group scheme actions on projective schemes
Gotou, Rin
Okuyama, Yûsuke
Algebraic Geometry
Dynamical Systems
Primary 14L24, Secondary 14L30, 32P05
Let $K$ be an algebraically closed and complete non-archimedean and non-trivially valued field, and let $G$ be a reductive group scheme acting on a flat projective scheme $X$ defined over the base ring of $K$-integers. For every $K$-point $x$ in $X$, we introduce the minimal invariant locus $\operatorname{MinInvLoc}_x$ and the semistable reduction translation locus $\operatorname{SSRL}_x$ in the translation space $\operatorname{BT}_G(K)$ associated with $G_K$, which is a variant of Bruhat-Tits building, and establish not only the coincidence of those loci but, under a mild completeness assumption, also their non-emptiness. In the dynamical setting which has been studied by Szpiro--Tepper--Williams and Rumely, the coincidence result is already new in higher dimensions, and the non-emptiness result includes Rumely's $1$-dimensional result at least in the spherical complete case.
title Semistable reductions and minimalities of invariants for group scheme actions on projective schemes
topic Algebraic Geometry
Dynamical Systems
Primary 14L24, Secondary 14L30, 32P05
url https://arxiv.org/abs/2604.25659