Department of

# Mathematics

Seminar Calendar
for events the day of Monday, September 30, 2019.

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events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
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Monday, September 30, 2019

3:00 pm in 243 Altgeld Hall,Monday, September 30, 2019

#### New action-angle variables on coadjoint orbits

###### Yanpeng Li (University of Geneva)

Abstract: The problem of constructing global action-angle variables on coadjoint orbits of compact Lie groups is one of the interesting questions in the theory of integrable systems. A fundamental contribution was made by Guillemin-Sternberg who constructed the Gelfand-Zeitlin integrable systems on coadjoint orbits of the groups SU(n) and SO(n). Recently, toric degeneration techniques allowed for the construction of global action-angle variables on rational coadjoint orbits of compact Lie groups of all types. In this talk, I will present a new approach which aims at constructing global action-angle coordinates on all regular coadjoint orbits of compact Lie groups and on a large family of related Hamiltonian spaces. It combines the results of Ginzburg-Weinstein on the theory of Poisson-Lie groups and the theory of cluster algebras using the "partial tropicalization'' procedure.

3:00 pm in 441 Altgeld Hall,Monday, September 30, 2019

#### The Recognition Principle for Infinite Loop Spaces

###### Brian Shin (UIUC Math)

Abstract: In this expository talk, I'd like to discuss the infinite loop space recognition principle. In particular, I'd like to examine Boardman-Vogt's infinite loop space machine from a modern view point.

4:00 pm in 241 Altgeld Hall,Monday, September 30, 2019

#### Anxiety and Stress Management Workshop

###### Counselling Center Professionals

5:00 pm in 243 Altgeld Hall,Monday, September 30, 2019

#### Anxiety and Stress Management Graduate Student Panel

###### (AWM)

Abstract: Graduate students will share their experiences on how they dealt with the inevitable stress of graduate life, especially during their first year. Also, cookies will be provided!