English

Points in the fppf topology

Algebraic Geometry 2016-01-27 v2

Abstract

Using methods from commutative algebra and topos-theory, we construct topos-theoretical points for the fppf topology of a scheme. These points are indexed by both a geometric point and a limit ordinal. The resulting stalks of the structure sheaf are what we call fppf-local rings. We show that for such rings all localizations at primes are henselian with algebraically closed residue field, and relate them to AIC and TIC rings. Furthermore, we give an abstract criterion ensuring that two sites have point spaces with identical sobrification. This applies in particular to some standard Grothendieck topologies considered in algebraic geometry: Zariski, etale, syntomic, and fppf.

Keywords

Cite

@article{arxiv.1407.5446,
  title  = {Points in the fppf topology},
  author = {Stefan Schröer},
  journal= {arXiv preprint arXiv:1407.5446},
  year   = {2016}
}

Comments

25 pages, minor changes, to appear in Ann. Sc. Norm. Super. Pisa Cl. Sci

R2 v1 2026-06-22T05:08:45.336Z