The étale site of the stable module category of a finite group

Date & time

3.30–4.30pm 17 April 2018


John Dedman Building 27, Room G35.


Bregje Pauwels

To any tensor-triangulated category T, there is a natural way to associate a site and a sheaf cohomology. The objects in this site are the commutative separable monoids in T. For instance, if T is the derived category of quasi-coherent sheaves on a scheme X, then the site fits in between the classical étale site and the recently discovered pro-étale site on X.

In this talk, I will explain what separable monoids are and show how they pop up in various settings. For a finite group G, I will show that the compact separable monoids in both the derived and stable module category of G correspond to G-sets. This allows us to describe the site associated to the derived and stable module category of G, to compute the corresponding sheaf cohomology and its relation to traditional group cohomology.

Updated:  27 April 2018/Responsible Officer:  Director/Page Contact:  School Manager