[Binghamton Geometry/Topology Seminar] This week: Jun Li

[jwilliams at math.binghamton.edu]

Speaker: Jun Li (University of Minnesota)

Title: The symplectomorphism groups of rational surfaces

Abstract: This talk is on the topology of $Symp(M,\omega)$, where
$Symp(M,\omega)$ is the symplectomorphism group of a symplectic rational
surface $(M,\omega)$. We will illustrate our approach with the 5 point
blowup of the projective plane. For an arbitrary symplectic form on this
rational surface, we are able to determine the symplectic mapping class
group (SMC) and describe the answer in terms of the Dynkin diagram of
Lagrangian sphere classes. In particular, when deforming the symplectic
form, the SMC of a rational surface behaves in the way of forgetting
strand map of braid groups.  We are also able to compute the fundamental
group of $Symp(M,\omega)$ for an open region of the symplectic cone. This
is a joint work with Tian-Jun Li and Weiwei Wu.

Thursday, March 1, 2:50pm, WH 100E