Singularities on vertical $ε$-log canonical Fano fibrations

Fuente: arXiv
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Auteurs principaux: Birkar, Caucher, Chen, Bingyi
Format: Preprint
Publié: 2024
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author Birkar, Caucher
Chen, Bingyi
author_facet Birkar, Caucher
Chen, Bingyi
contents Given a Fano type log Calabi-Yau fibration $(X,B)\to Z$ with $(X,B)$ being $ε$-lc, the first author in \cite{Bi23} proved that the generalised pair $(Z,B_Z+M_Z)$ given by the canonical bundle formula is generalised $δ$-lc where $δ>0$ depends only on $ε$ and $\dim X-\dim Z$, which confirmed a conjecture of Shokurov. In this paper, we prove the above result under a weaker assumption. Instead of requiring $(X,B)$ to be $ε$-lc, we assume that $(X,B)$ is $ε$-lc vertically over $Z$, that is, the log discrepancy of $E$ with respect to $(X,B)$ is $\geq ε$ for any prime divisor $E$ over $X$ whose center on $X$ is vertical over $Z$.
format Preprint
id arxiv_https___arxiv_org_abs_2412_09382
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Singularities on vertical $ε$-log canonical Fano fibrations
Birkar, Caucher
Chen, Bingyi
Algebraic Geometry
Given a Fano type log Calabi-Yau fibration $(X,B)\to Z$ with $(X,B)$ being $ε$-lc, the first author in \cite{Bi23} proved that the generalised pair $(Z,B_Z+M_Z)$ given by the canonical bundle formula is generalised $δ$-lc where $δ>0$ depends only on $ε$ and $\dim X-\dim Z$, which confirmed a conjecture of Shokurov. In this paper, we prove the above result under a weaker assumption. Instead of requiring $(X,B)$ to be $ε$-lc, we assume that $(X,B)$ is $ε$-lc vertically over $Z$, that is, the log discrepancy of $E$ with respect to $(X,B)$ is $\geq ε$ for any prime divisor $E$ over $X$ whose center on $X$ is vertical over $Z$.
title Singularities on vertical $ε$-log canonical Fano fibrations
topic Algebraic Geometry
url https://arxiv.org/abs/2412.09382