Weak approximation for Fano complete intersections in positive characteristic
Abstract
For a smooth curve over an algebraically closed field , for every -flat complete intersection in of type , if the Fano index is and if , we prove weak approximation of -points of by -points at all places of (strong) potentially good reduction, including all places of good reduction. The key step is the proof that such complete intersections are \emph{separably uniruled by lines}, and even \emph{separably rationally connected}, whenever smooth. We prove that the inequality is close to sharp. We prove a similar theorem for Fano manifolds of Picard number and Fano index .
Cite
@article{arxiv.1811.02466,
title = {Weak approximation for Fano complete intersections in positive characteristic},
author = {Jason Michael Starr and Zhiyu Tian and Runhong Zong},
journal= {arXiv preprint arXiv:1811.02466},
year = {2018}
}
Comments
22 pages. Following discussions with Shizhang Li and Bhargav Bhatt, added hypothesis about torsion in crystalline cohomology for specializations of complex Fano manifolds of Picard number $1$ and Fano index $1$. Also proved a version eliminating this hypothesis and the hypothesis that the mixed characteristic DVR is unramified