English

Congruence for rational points over finite fields and coniveau over local fields

Number Theory 2007-06-08 v1 Algebraic Geometry

Abstract

If the \ell-adic cohomology of a projective smooth variety, defined over a local field KK with finite residue field kk, is supported in codimension 1\ge 1, then every model over the ring of integers of KK has a kk-rational point. For KK a pp-adic field, this is math/0405318, Theorem 1.1. If the model \sX\sX is regular, one has a congruence \sX(k)1|\sX(k)|\equiv 1 modulo k|k| for the number of kk-rational points 0704.1273, Theorem 1.1. The congruence is violated if one drops the regularity assumption.

Keywords

Cite

@article{arxiv.0706.0972,
  title  = {Congruence for rational points over finite fields and coniveau over local fields},
  author = {Hélène Esnault and Chenyang Xu},
  journal= {arXiv preprint arXiv:0706.0972},
  year   = {2007}
}
R2 v1 2026-06-21T08:36:09.055Z