English

Grothendieck-Lefschetz for vector bundles

Algebraic Geometry 2020-05-25 v4 Commutative Algebra

Abstract

According to the Grothendieck-Lefschetz theorem from SGA 2, there are no nontrivial line bundles on the punctured spectrum URU_R of a local ring RR that is a complete intersection of dimension 4\ge 4. Dao conjectured a generalization for vector bundles V\mathscr{V} of arbitrary rank on URU_R: such a V\mathscr{V} is free if and only if depthR(EndR(Γ(UR,V)))4\mathrm{depth}_R(\mathrm{End}_R(\Gamma(U_R, \mathscr{V}))) \ge 4. We use deformation theoretic techniques to settle Dao's conjecture. We also present examples showing that its assumptions are sharp and draw consequences for splitting of vector bundles on complete intersections in projective space.

Keywords

Cite

@article{arxiv.1802.08203,
  title  = {Grothendieck-Lefschetz for vector bundles},
  author = {Kestutis Cesnavicius},
  journal= {arXiv preprint arXiv:1802.08203},
  year   = {2020}
}

Comments

8 pages; corrected minor typos pointed out by the copyeditors; final version, to appear in Algebraic Geometry

R2 v1 2026-06-23T00:30:30.930Z