English

Bertini theorems for singular schemes and nearby cycles in mixed characteristic

Number Theory 2014-06-05 v3 Algebraic Geometry

Abstract

We first study hyperplane sections of some singular schemes over a field. We prove a Bertini theorem for the log smoothness of generic hyperplane sections of a large class of log smooth schemes over a log point. We also give an abstract generalization of the usual Bertini theorem for smoothness. We then apply this result to the study of hyperplane sections of regular schemes over a complete discrete valuation ring of characteristic zero with algebraically closed residue field. Lastly, give an exposition of a result of Faltings which states that one can compute the pp-adic nearby cycles of smooth schemes over a discrete valuation ring of mixed characteristic as Galois cohomology.

Keywords

Cite

@article{arxiv.1310.5020,
  title  = {Bertini theorems for singular schemes and nearby cycles in mixed characteristic},
  author = {Rémi Lodh},
  journal= {arXiv preprint arXiv:1310.5020},
  year   = {2014}
}

Comments

27 pages; some claims of v1 wrong, paper corrected accordingly