seminars:topsem

## Geometry and Topology Seminar

We meet Thursdays at 2:50–3:50 pm in WH-100E followed by refreshments served from 4:00–4:25 pm in WH-102. This semester's organizer is Jonathan Williams.

Some seminar speakers will also give a colloquium talk at 4:30 pm on the same day as the seminar talk. This seminar is partly funded as one of Dean's Speaker Series in Harpur College (College of Arts and Sciences) at Binghamton University.

The seminar has an announcement mailing list open to all. There is also a Google calendar with the seminar schedule (also in iCal).

# Spring 2018

• March 1
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.

• March 8
Speaker: Lisa Piccirillo (UT-Austin)
Title: TBA

Abstract: TBA

• March 15
Speaker: Gili Golan (Vanderbilt University)
Title: TBA

Abstract: TBA

• March 22
Speaker: Yair Hartman (Northwestern University)
Title: Stationary C*-Dynamical Systems

Abstract: We introduce the notion of stationary actions in the context of C*-algebras, and prove a new characterization of C*-simplicity in terms of unique stationarity. This ergodic-theoretic characterization provides an intrinsic understanding for the relation between C*-simplicity and the unique trace property, and provides a framework in which C*-simplicity and random walks interact. Joint work with Mehrdad Kalantar.

• March 29
Speaker: Speaker (institution)
Title: TBA

Abstract: TBA

• April 5 (no seminar - Spring break)
• April 12 2018 Hilton Memorial lecture
Speaker: Vaughan Jones (Berkeley)
Title: Local scale transformations in one dimension

Special time and place: 3pm–4pm in AA G023

• April 19
Speaker: Akram Alishahi (Columbia)
Title: TBA

Abstract: TBA

• April 26
Speaker: Laura Starkston (Stanford)
Title: TBA

Abstract: TBA

• May 3
Speaker: Jamie Conway (UC Berkeley)
Title: TBA

Abstract: TBA