# Geometry and Topology Seminar

The Geometry and Topology seminar meets in room 901 of Van Vleck Hall on Fridays from 1:20pm - 2:10pm. For more information, contact Shaosai Huang.

In the fall of 2020, we will hold online meetings on Zoom platform (available every Friday 1:00pm - 2:30pm).

## Fall 2020

date speaker title host(s)
Oct. 23 Yu Li (Stony Brook) On the ancient solutions to the Ricci flow (Huang)
Oct. 30 Yi Lai (Berkeley) A family of 3d steady gradient solitons that are flying wings (Huang)
Nov. 6 Jiyuan Han (Purdue) TBA (Chen)
Nov. 20 Max Hallgren (Cornell) TBA (Huang)
Dec. 4 Yang Li (IAS) TBA (Chen)

## Fall Abstracts

### Yu Li

Ancient solutions model the singularity formation of the Ricci flow.  In two and three dimensions, we currently have complete classifications for κ-noncollapsed ancient solutions, while the higher dimensional problem remains open. This talk will survey some recent developments of κ-noncollapsed ancient solutions with nonnegative curvature in higher dimensions.

### Yi Lai

We found a family of $\mathbb{Z}_2\times O(2)$-symmetric 3d steady gradient Ricci solitons. We show that these solitons are all flying wings. This confirms a conjecture by Hamilton.