English

$K(\pi, 1)$-neighborhoods and comparison theorems

Algebraic Geometry 2015-10-28 v1 Number Theory

Abstract

A technical ingredient in Faltings' original approach to p-adic comparison theorems involves the construction of K(π,1)K(\pi, 1)-neighborhoods for a smooth scheme X over a mixed characteristic dvr with a perfect residue field: every point of X has an open neighborhood whose general fiber is a K(π,1)K(\pi, 1) scheme (a notion analogous to having a contractible universal cover). We show how to extend this result to the logarithmically smooth case, which might help to simplify some proofs in p-adic Hodge theory. The main ingredient of the proof is a variant of a trick of Nagata used in his proof of the Noether Normalization Lemma.

Keywords

Cite

@article{arxiv.1407.0337,
  title  = {$K(\pi, 1)$-neighborhoods and comparison theorems},
  author = {Piotr Achinger},
  journal= {arXiv preprint arXiv:1407.0337},
  year   = {2015}
}

Comments

24 pages

R2 v1 2026-06-22T04:52:45.068Z