Polarized endomorphisms of normal projective threefolds in arbitrary
characteristic
characteristic
File(s)1710.01903v3.pdf (407.81 KB)
Accepted version
Author(s)
Cascini, Paolo
Meng, Sheng
Zhang, De-Qi
Type
Journal Article
Abstract
Let X be a projective variety over an algebraically closed field k of arbitrary characteristic p≥0. A surjective endomorphism f of X is q-polarized if f∗H∼qH for some ample Cartier divisor H and integer q>1. Suppose f is separable and X is Q-Gorenstein and normal. We show that the anti-canonical divisor −KX is numerically equivalent to an effective Q-Cartier divisor, strengthening slightly the conclusion of Boucksom, de Fernex and Favre (Duke Math J 161(8):1455–1520, 2012, Theorem C) and also covering singular varieties over an algebraically closed field of arbitrary characteristic. Suppose f is separable and X is normal. We show that the Albanese morphism of X is an algebraic fibre space and f induces polarized endomorphisms on the Albanese and also the Picard variety of X, and KX being pseudo-effective and Q-Cartier means being a torsion Q-divisor. Let fGal:X¯¯¯¯→X be the Galois closure of f. We show that if p>5 and co-prime to degfGal then one can run the minimal model program (MMP) f-equivariantly, after replacing f by a positive power, for a mildly singular threefold X and reach a variety Y with torsion canonical divisor (and also with Y being a quasi-étale quotient of an abelian variety when dim(Y)≤2). Along the way, we show that a power of f acts as a scalar multiplication on the Neron-Severi group of X (modulo torsion) when X is a smooth and rationally chain connected projective variety of dimension at most three.
Date Issued
2020-10-01
Date Acceptance
2019-07-21
Citation
Mathematische Annalen, 2020, 378, pp.637-665
ISSN
0025-5831
Publisher
Springer (part of Springer Nature)
Start Page
637
End Page
665
Journal / Book Title
Mathematische Annalen
Volume
378
Copyright Statement
© 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Identifier
http://arxiv.org/abs/1710.01903v2
Grant Number
EP/L018667/1
Subjects
math.AG
math.AG
math.DS
14H30, 32H50, 14E30, 11G10, 08A35
Notes
Some minor improvement. Appendix is combined into the main text. 32 pages
Publication Status
Published
Date Publish Online
2019-07-31