Baohua FUAMSS, Chinese Acedemy of SciencesJun-Muk HwangKIAS
mathscidoc:1702.01005
J. Algebraic Geometry
A birational transformation f: P^n --> Z, where Z is a nonsingular variety of Picard number 1, is called a special birational transformation of type (a, b) if f is given by a linear system of degree a, its inverse is given by a linear system of degree b and the base locus S \subset P^n of f is irreducible and nonsingular.
In this paper, we classify special birational transformations of type (2,1). In addition to previous works Alzati-Sierra and Russo on this topic, our proof employs natural C^*-actions on Z in a crucial way. These C^*-actions also relate our result to the problem studied in our previous work on smooth projective varieties with nonzero prolongations.
@inproceedings{baohuaspecial,
title={Special birational transformations of type (2,1)},
author={Baohua FU, and Jun-Muk Hwang},
url={http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170210114435182925424},
booktitle={J. Algebraic Geometry},
}
Baohua FU, and Jun-Muk Hwang. Special birational transformations of type (2,1). In J. Algebraic Geometry. http://archive.ymsc.tsinghua.edu.cn/pacm_paperurl/20170210114435182925424.