English

Factorial threefolds and Shokurov vanishing

Algebraic Geometry 2007-05-23 v4 Differential Geometry

Abstract

We prove the factoriality of the following nodal threefolds: a complete intersection of hypersurfaces FF and GP5G\subset\mathbb{P}^{5} of degree nn and kk respectively, where GG is smooth, Sing(FG)(n+k2)(n1)/5|\mathrm{Sing}(F\cap G)|\leqslant(n+k-2)(n-1)/5, nkn\geqslant k; a double cover of a smooth hypersurface FP4F\subset\mathbb{P}^{4} of degree nn branched over a surface that is cut out on FF by a hypersurface GG of degree 2rn2r\geqslant n, and Sing(FG)(2r+n2)r/4|\mathrm{Sing}(F\cap G)|\leqslant(2r+n-2)r/4.

Keywords

Cite

@article{arxiv.math/0410252,
  title  = {Factorial threefolds and Shokurov vanishing},
  author = {Ivan Cheltsov},
  journal= {arXiv preprint arXiv:math/0410252},
  year   = {2007}
}

Comments

22 pages, extended version, to appear in Sbornik: Mathematics

R2 v1 2026-07-22T17:11:01.668Z