Boundedness of Fano type fibrations
Abstract
In this paper, we prove various results on boundedness and singularities of Fano fibrations and of Fano type fibrations. A Fano fibration is a projective morphism of algebraic varieties with connected fibres such that is Fano over , that is, has "good" singularities and is ample over . A Fano type fibration is similarly defined where is assumed to be close to being Fano over . This class includes many central ingredients of birational geometry such as Fano varieties, Mori fibre spaces, flipping and divisorial contractions, crepant models, germs of singularities, etc. We develop the theory in the more general framework of log Calabi-Yau fibrations. Dans cet article, nous prouvons divers r\'esultats sur les limites et les singularit\'es de fibrations de Fano et les fibrations de type Fano. Une fibration de Fano est un morphisme projectif de vari\'et\'es alg\'ebriques \`a fibres connexes tel que est Fano sur , c'est-\`a-dire que a de "bonnes" singularit\'es et est ample sur . Une fibration de type Fano est d\'efinie de fa\c{c}on similaire quand est suppos\'e \^etre proche d'\^etre Fano sur . Cette classe comprend de nombreux ingr\'edients centraux de g\'eom\'etrie birationnelle tels que les vari\'et\'es de fano, les espaces de fibres Mori, le flip et les contractions divisorielles, les mod\`eles r\'ep\'etiteurs, les germes de singularit\'es, etc. Nous d\'eveloppons la th\'eorie dans le cadre plus g\'en\'eral des log-fibrations de Calabi-Yau.
Keywords
Cite
@article{arxiv.2209.08797,
title = {Boundedness of Fano type fibrations},
author = {Caucher Birkar},
journal= {arXiv preprint arXiv:2209.08797},
year = {2022}
}
Comments
To appear in Ann. Sci. ENS, 48 pages; this paper consists of the results of arXiv:1811.10709 on Fano type fibrations; the latter is kept because it contains other results and there are many references to it