# Seminars in geometry/topology

The Topology Seminar Spring 2019 will be on **Mondays** 13:15 - 14:15 (or 14:00 - 15:00) in room 734, Sentralbygg 2.

## Spring 2019 - Upcoming Talks

## February 25, 13:15 - 14:15, room 734, Sentralbygg 2

**Jarl Gunnar Taxerås Flaten (NTNU): Programming with Category Theory**

**Abstract:** Haskell is a programming language heavily inspired by category theory. We'll start by seeing how basic category theory is represented in this language, before having a deeper look at what monads are and their different uses here. Anyone with some familiarity with algebra is welcome—especially those who don't believe pure mathematics has real, practical uses!

## April 1, 13:15 - 14:15, room 734, Sentralbygg 2

**Ambrus Pal (Imperial College London): An arithmetic Yau-Zaslow formula**

**Abstract:** We prove an arithmetic refinement of the Yau–Zaslow formula by replacing the classical Euler characteristic in Beauville’s argument by a variant of Levine’s motivic Euler characteristic. We derive several similar formulas for other related invariants, including Saito’s determinant of cohomology, and a generalisation of a formula of Kharlamov and Rasdeaconu on counting real rational curves on real K3 surfaces. Joint work with Frank Neumann.