28 mar 2012 -- 17:00
Sala Seminari, Department of Mathematics, Pisa University
Inspired by the density function for mean curvature flow introduced by A. Stone and based on Huisken's monotonicity formula, we define a similar quantity for the Ricci flow, related to the monotonicity of Perelman's W-functional. We discuss its connections with the singularities in the "Type-I case" and we give an alternative proof of the result of Enders, Mueller and Topping that around a type-one singular point, blowing-up the flow in a suitable way, one obtains a shrinking gradient Ricci soliton in the geometric limit (in every dimension). In perspective, this line of analysis could work also for general singular points (also type-II) in dimension two and three (and very hopefully four). This would give another and more natural method to get an asymptotic shrinking gradient Ricci soliton, alternative to Perelman's blow-upblow-down procedure.