Abstract: The notion of a "t-structure on a triangulated category" was introduced around 1980. The notion of "co-t-structure" could have been defined back then as well, but it didn't receive much attention until the past 10 years or so, probably because it wasn't clear what it was good for. I'll explain these notions and give some elementary examples. I will then discuss some "modern" examples of co-t-structures in geometric representation theory. In particular, I will explain a remarkable new co-t-structure on the derived category of coherent sheaves on the nilpotent cone of a reductive group. The study of this co-t-structure leads to the proof of the Humphreys conjecture on tilting modules for a reductive group. This is joint work with W. Hardesty.

Zoom link: https://yale.zoom.us/j/99305994163, contact the organizers (Gurbir Dhillon and Junliang Shen) for the passcode.