Date: Tuesday, April 16, 2013
Location: 1360 East Hall (3:00 PM to 4:00 PM)
Title: The Göttsche conjecture
Abstract: I will describe a classical problem going back to 1848 (Steiner, Cayley, Salmon,...) and a solution using simple techniques that one would never have thought of without ideas coming from string theory (Gromov-Witten invariants, BPS states) and modern geometry (the Maulik-Nekrasov-Okounkov-Pandharipande conjecture). In generic families of curves C on a complex surface S, nodal curves - those with the simplest possible singularities - appear in codimension 1. More generally those with d nodes occur in codimension d. In particular a d-dimensional linear family of curves should contain a finite number of such d-nodal curves. The classical problem - at least in the case of S being the projective plane - is to determine this number. The G ̈ottsche conjecture states that the answer should be topological, given by a universal degree d polynomial in the four numbers (C · C), (c1(S) · C), (c1(S)2), and c2(S).
This was proved recently by Yu-Jong Tzeng. I will explain a simpler proof which was joint work with Martijn Kool and Vivek Shende. The treatment will be very low-tech; I won’t assume any prior knowledge. The main tool is Euler characteristics (which I will also explain).
Speaker: Richard Thomas
Institution: Imperial College
Event Organizer:
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