Dear All,

On Monday 07/04/2025, at 12:00 via Zoom, Leonid Positselski (Czech Academy of Sciences), will give a talk in our Seminar.

Title: Derived categories of the second kind and Koszul duality

Abstract: I will start with introducing curved DG-rings and the hat
construction (the correspondence between curved DG-rings and
acyclic DG-rings), and explaining that the DG-category of DG-modules
over the double hat DG-ring is equivalent to the DG-category of
CDG-modules over the original CDG-ring.  Then I will define
the derived categories of the second kind as triangulated categories
attached to an abelian DG-category.  Finally, I will survey various
versions of absolute and relative Koszul duality, including
the case of DG-algebras and CDG-coalgebras over a field, the case
of nonhomogeneous Koszul rings over base rings, and the case of
nonhomogeneous Koszul semialgebras over coalgebras over a field,
emphasizing the role of the inverse hat construction.

Below is the Zoom link:

https://authgr.zoom.us/j/4591058197?pwd=MEZVUFVSenc5M2h2WW5FRERybXBwdz09

Best wishes,
Chrysostomos Psaroudakis