[geometry-ml:02619] MS seminar at Kavli IPMU -- Michael Wemyss (U of Edinburgh) -- April 8

[Todor Milanov]

Dear all,

I would like to announce the following Mathematics and String theory seminar at IPMU.

Speaker:	Michael Wemyss	(U of Edinburgh)
Date:	Fri, Apr 08, 2016, 13:15 - 14:45
Place:	Seminar Room A

Title: Affine actions from 3-fold flops, and tilings of the plane.

Abstract: I will begin by explaining how flops arise in algebraic geometry, and how it is difficult to iterate.  However, wh
en viewed from a cluster/homological perspective, it becomes easier, and I will outline what structures we expect to see alg
ebraically. The expectation, now proved in many cases, is that flops induce some type of “affine pure braid group” acting 
on the derived category.  I will explain the Coxeter combinatorics background behind this, which is completely independent o
f the geometric motivation.  The remarkable thing is that the geometry predicts unseen algebraic phenomenon, like an affine 
version of the symmetries of the pentagon (which does not exist!), and most of the talk will be motivated by the simplest ca
se of two intersecting flopping curves.  Towards the end I will explain how this case is related to certain tilings of the p
lane, and indeed every choice of two nodes of a Dynkin diagram induces a tiling of the plane.  These tilings seem to be new,
 and are somewhat mysterious. 


-----------------------------

Todor Eliseev Milanov
Associate Professor 
Kavli IPMU,  Japan

todor.milanov ＠ ipmu.jp