This week we will have Will Donovan (Tsinghua University) speaking in the algebra seminar. We will go out for lunch after the talk. When: Friday 12 April, 12-1pm Where: Carslaw 273 (Note the new location!) Title: Geometrification of monodromy for hypergeometric systems Abstract: The Gauss hypergeometric equation controls solutions of second-order linear differential equations with three regular singular points. These solutions encompass a zoo of special functions, with rich and useful structure. Moving the complex variable around a singular point in the domain leads to a monodromy action on the solutions. I will explain a ’geometrification’ of this action, using the K-theory of Calabi-Yau 3-folds. If time permits, I will introduce work in progress with Weilin Su extending this to multi-parameter analogs of the Gauss equation, via a further ’categorification’ using the derived category of coherent sheaves.