# Events for November 28, 2017 from General and Seminar calendars

## Working Seminar in Orbit Equivalence and Measured Group Theory

Time: 2:00PM - 3:00PM

Location: BLOC 220

Title: Stable Actions and Central Extensions II

Abstract: The proof of the main theorem will be continued via the usage of co-induced actions for equivalence relations.

## Mathematical Physics and Harmonic Analysis Seminar

Time: 4:00PM - 5:00PM

Location: BLOC 624

Speaker: Semyon Dyatlov, MIT/Berkeley

Title: Lower bounds on eigenfunctions on hyperbolic surfaces

Abstract: I show that on a compact hyperbolic surface, the mass of an $L^2$-normalized eigenfunction of the Laplacian on any nonempty open set is bounded below by a positive constant depending on the set, but not on the eigenvalue. This statement, more precisely its stronger semiclassical version, has many applications including control for the Schr\"odinger equation and the full support property for semiclassical defect measures. The key new ingredient of the proof is a fractal uncertainty principle, stating that no function can be localized close to a porous set in both position and frequency. This talk is based on joint works with Long Jin and with Jean Bourgain.

## Student/Postdoc Working Geometry Seminar

Time: 5:00PM - 6:00PM

Location: BLOC 628

Speaker: P. Sarin, TAMU

Title: Surgery cont'd