English

Global generation and very ampleness for adjoint linear series

Algebraic Geometry 2018-04-10 v3 Complex Variables

Abstract

Let XX be a smooth projective variety over an algebraically closed field K\mathbb{K} with arbitrary characteristic. Suppose LL is an ample and globally generated line bundle. By Castelnuovo--Mumford regularity, we show that KXLdimXAK_X \otimes L^{\otimes \dim X} \otimes A is globally generated and KXL(dimX+1)AK_X \otimes L^{\otimes (\dim X+1)} \otimes A is very ample, provided the line bundle AA is nef but not numerically trivial. On complex projective varieties, by investigating Kawamata-Viehweg-Nadel type vanishing theorems for vector bundles, we also obtain the global generation for adjoint vector bundles. In particular, for a holomorphic submersion f:XYf:X\longrightarrow Y with LL ample and globally generated, and AA nef but not numerically trivial, we prove the global generation of f(KX/Y)sKYLdimYA f_*(K_{X/Y})^{\otimes s}\otimes K_Y \otimes L^{\otimes \dim Y} \otimes A for any positive integer ss.

Keywords

Cite

@article{arxiv.1606.02046,
  title  = {Global generation and very ampleness for adjoint linear series},
  author = {Xiaoyu Su and Xiaokui Yang},
  journal= {arXiv preprint arXiv:1606.02046},
  year   = {2018}
}

Comments

To appear in Comm. Anal. Geom

R2 v1 2026-06-22T14:19:19.546Z