On freeness theorem of the adjoint bundle on a normal surface
alg-geom
2008-02-03 v1 Algebraic Geometry
Abstract
We extend Reider's freeness criterion to normal surfaces of characteristic 0. Let Y be a normal surface. Let D be a nef divisor on Y such that K_Y+D is a Cartier divisor. Let x be a point on Y. If x is a base point of |K_Y+D| and D^2>\delta_x (\delta_x is determined by x, \delta_x <= 4) then there exists a non zero effective divisor E on Y passing through x such that 0 <= DE <= \delta_x /2, DE - \delta_x /4 <= E^2 <= (DE)^2 / D^2, E^2 < 0 if DE=0.
Cite
@article{arxiv.alg-geom/9603022,
title = {On freeness theorem of the adjoint bundle on a normal surface},
author = {Takeshi Kawachi},
journal= {arXiv preprint arXiv:alg-geom/9603022},
year = {2008}
}
Comments
AmS-TeX 2.1 + 4 PostScript files, 29 pages