English

Deforming elephants of Q-Fano threefolds

Algebraic Geometry 2016-09-23 v3

Abstract

We study deformations of a pair of a Q\mathbb{Q}-Fano 33-fold XX with only terminal singularities and its elephant DKXD \in |{-}K_X|. We prove that, if there exists DKXD \in |{-}K_X| with only isolated singularities, the pair (X,D)(X,D) can be deformed to a pair of a Q\mathbb{Q}-Fano 33-fold with only quotient singularities and a Du Val elephant. When there are only non-normal elephants, we reduce the existence problem of such a deformation to a local problem around the singular locus of the elephant. We also give several examples of Q\mathbb{Q}-Fano 33-folds without Du Val elephants.

Keywords

Cite

@article{arxiv.1404.0909,
  title  = {Deforming elephants of Q-Fano threefolds},
  author = {Taro Sano},
  journal= {arXiv preprint arXiv:1404.0909},
  year   = {2016}
}

Comments

31 pages, to appear in Jounal of LMS