Almost minimal models of log surfaces

Fuente: arXiv
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Autor principal: Palka, Karol
Formato: Preprint
Publicado: 2024
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author Palka, Karol
author_facet Palka, Karol
contents We generalize Miyanishi's theory of almost minimal models of log smooth surfaces with reduced boundary to the case of arbitrary log surfaces defined over an algebraically closed field. Given an MMP run of a log surface $(X,D)$ we define and construct its almost minimal model, whose underlying surface has singularities not worse than $X$ and which differs from a minimal model by a contraction of some curves supported in the boundary only. For boundaries of type $rD$, where $D$ is reduced and $r\in [0,1]\cap \mathbb{Q}$, we show that if $X$ is smooth or $r\in [0,\frac{1}{2}]$ then the construction respects $(1-r)$-divisorial log terminality and $(1-r)$-log canonicity. We show that the assumptions are optimal, too.
format Preprint
id arxiv_https___arxiv_org_abs_2402_07187
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Almost minimal models of log surfaces
Palka, Karol
Algebraic Geometry
14E30, 14J17
We generalize Miyanishi's theory of almost minimal models of log smooth surfaces with reduced boundary to the case of arbitrary log surfaces defined over an algebraically closed field. Given an MMP run of a log surface $(X,D)$ we define and construct its almost minimal model, whose underlying surface has singularities not worse than $X$ and which differs from a minimal model by a contraction of some curves supported in the boundary only. For boundaries of type $rD$, where $D$ is reduced and $r\in [0,1]\cap \mathbb{Q}$, we show that if $X$ is smooth or $r\in [0,\frac{1}{2}]$ then the construction respects $(1-r)$-divisorial log terminality and $(1-r)$-log canonicity. We show that the assumptions are optimal, too.
title Almost minimal models of log surfaces
topic Algebraic Geometry
14E30, 14J17
url https://arxiv.org/abs/2402.07187