Columbia Mathematics Department Colloquium




Frans Oort

(Utrecht and Columbia)


Where is the terminology "monodromy" used for the first time in history? We will discuss historical roots of this topic in the 19-th century and compare these

with work on monodromy in the 20-th century.  Then we will see how the use of a differential equation enables us to compute a class number

(a beautiful proof by Igusa, later generalized in various disguises). We will see how Honda-Tate theory (the topic of our Friday graduate seminar)

 gives a computation of a monodromy group (as shown by Ribet). And I will conclude by describing joint work with Ching-Li Chai,where we compute

 l-adic and p-adic monodromy on  certain subvarieties of the moduli space of abelian varieties (which connects with my Eilenberg lectures on Fridays).



  October 8th, Wednesday, 5:00-6:00 pm

Mathematics 520

Tea will be served at 4:30pm