Holmstrom Grothendieck topology II

http://mathoverflow.net/questions/117595/points-in-sites-etale-fppf

http://mathoverflow.net/questions/39212/infima-and-suprema-of-grothendieck-topologies

http://mathoverflow.net/questions/8115/does-sheafification-preserve-sheaves-for-a-different-topology

http://mathoverflow.net/questions/14486/precise-definition-of-a-scheme-functor-of-points

http://mathoverflow.net/questions/15979/motivation-for-the-etale-topology-over-other-possibilities

http://mathoverflow.net/questions/20251/cohomology-of-sheaves-in-different-grothendieck-topologies

nlab entries: etale

arXiv:1210.0431 Topologies de Grothendieck, descente, quotients fra arXiv Front: math.AG av Sylvain Brochard In this note, we present a few existence theorems for the quotient of a scheme by the action of a group. The first two sections are devoted to Grothendieck topologies and descent theory. The third one is dealing with quotients: we first give direct and (almost) complete proofs for the main existence results of SGA 3, exposé V. Then we discuss some specific situations: the quotient of an algebraic group over a field by a subgroup, the quotient of a group by the normalizer of a smooth subgroup, and quotients of affine schemes by free actions of diagonalizable groups. From place to place, the original proofs have been slightly improved (e.g. with the use of algebraic spaces). This note grew out of lectures given by the author in the CIRM (Luminy) during the Summer School “Schémas en groupes” in 2011.

A Google Books link describing Amitsur cohomology as Cech cohomology, with some material on Groth tops.

nLab page on Grothendieck topology II

Created on June 9, 2014 at 21:16:14 by Andreas Holmström