Department of

# Mathematics

Seminar Calendar
for events the day of Monday, September 11, 2017.

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events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
     August 2017           September 2017          October 2017
Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa
1  2  3  4  5                   1  2    1  2  3  4  5  6  7
6  7  8  9 10 11 12    3  4  5  6  7  8  9    8  9 10 11 12 13 14
13 14 15 16 17 18 19   10 11 12 13 14 15 16   15 16 17 18 19 20 21
20 21 22 23 24 25 26   17 18 19 20 21 22 23   22 23 24 25 26 27 28
27 28 29 30 31         24 25 26 27 28 29 30   29 30 31



Monday, September 11, 2017

3:00 pm in 243 AH,Monday, September 11, 2017

#### Relative Floer theory and wall-crossing

###### James Pascaleff (UIUC)

Abstract: Given a monotone Lagrangian L in a monotone symplectic manifold, there is a function known as the disc potential that encodes counts of maslov index 2 discs with boundary on L. The behavior of this potential under certain geometric transformations of the Lagrangian (mutations) is governed by what is known as a "wall-crossing formula." In this talk I will present a new, simple argument that allows one to prove such formulas in a general setting. The main new ingredient is a reformulation of the problem in terms of relative Floer theory. This is joint work with Dmitry Tonkonog.

3:00 pm in 141 Altgeld Hall,Monday, September 11, 2017

#### What is tmf

###### Ningchuan Zhang   [email] (UIUC)

Abstract: In short, Topological Modular Forms (tmf) is a “universal elliptic cohomology theory”. More precisely, it is the global section of a sheaf of $E_\infty$-ring spectra over the moduli stack of (generalized) elliptic curves. In this talk, I’ll introduce tmf and sketch the construction of it (or really this sheaf of $E_\infty$ ring spectra). If time allows, I’ll also explain its relationship to classical modular forms.

4:00 pm in 245 Altgeld Hall,Monday, September 11, 2017