Seth Wolbert

(Department of Mathematics, University of Manitoba)

Categories Fibered In Groupoids

Date Friday, February 8, 2019

After some final words on Grothendieck topology, we will take the last step towards defining stacks over categories and discuss categories fibered in groupoids (CFGs for short). While one can think of stacks as a certain type of 2-functor from a site to the category of groupoids, it is more common to instead look at CFGs which could (arguably) be thought of as the graph of such a 2-functor. We will define and discuss the 2-category of CFGs this week to hopefully be fully prepared to discuss stacks in full during our next meeting.