Department of

# Mathematics

Seminar Calendar
for events the week of Wednesday, April 1, 2020.

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events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
      March 2020             April 2020              May 2020
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  6  7             1  2  3  4                   1  2
8  9 10 11 12 13 14    5  6  7  8  9 10 11    3  4  5  6  7  8  9
15 16 17 18 19 20 21   12 13 14 15 16 17 18   10 11 12 13 14 15 16
22 23 24 25 26 27 28   19 20 21 22 23 24 25   17 18 19 20 21 22 23
29 30 31               26 27 28 29 30         24 25 26 27 28 29 30
31


Monday, March 30, 2020

3:00 pm in 243 Altgeld Hall,Monday, March 30, 2020

#### To Be Announced (Cancelled)

###### Reyer Sjamaar (Cornell)

Abstract: This talk has been cancelled.

5:00 pm in 241 Altgeld Hall,Monday, March 30, 2020

#### Connes' embedding

###### David Gao (UIUC)

Abstract: We will have a zoom meeting where David will give an overveiw of the proof. Section 7 will be one week later. https://illinois.zoom.us/j/607953706

Tuesday, March 31, 2020

4:00 pm in Zoom Meeting,Tuesday, March 31, 2020

#### Quantum Resources What Are They and How Much Are They Worth?

###### Jamie Sikora (Perimeter Institute, Waterloo, ON)

Abstract: In this talk, I will discuss several natural quantum problems and, in particular, how the problems change as the quantum resources change. I will show how to take an economics perspective to assign a shadow price to each quantum resource. To do this, I will use optimization theory and show that shadow prices are often given for free if you know where to look for them. This will be a Zoom meeting (https://illinois.zoom.us/j/653578028). Faculty host: Marius Junge.

Wednesday, April 1, 2020

3:30 pm in https://illinois.zoom.us/j/806582029,Wednesday, April 1, 2020

#### Random walks on graphs and spectral radius: part 2

###### Anush Tserunyan (UIUC Math)

Abstract: We will continue discussing random walks on graphs and their spectral radius, computing that the spectral radius of $\mathbb{Z}^d$ is $1$, whereas it is less than $1$ for a $d$-regular tree with $d \ge 3$. We will then consider another parameter used in studying a given random walk, namely, the expectation of the number of visits to a fixed vertex. This controls the recurrence of the random walk and we will use it to deduce that the simple random walk on $\mathbb{Z}^d$ is recurrent if and only if $d \le 2$.

4:00 pm in 245 Altgeld Hall,Wednesday, April 1, 2020

#### A family of number-theoretic directed graphs on the integers

###### Dana Neidinger

11:00 pm in Altgeld Hall,Wednesday, April 1, 2020

#### Meeting with Jamie Sikora

###### Jamie Sikora

Thursday, April 2, 2020

11:00 am in 241 Altgeld Hall,Thursday, April 2, 2020

#### To Be Announced

4:00 pm in 245 Altgeld Hall,Thursday, April 2, 2020

#### To Be Announced

###### Kevin Purbhoo   [email] (University of Waterloo)

Abstract: To come.

Friday, April 3, 2020

3:00 pm in https://illinois.zoom.us/j/521113604,Friday, April 3, 2020

#### A dynamical obstruction for classification by actions of TSI Polish groups

###### Aristotelis Panagiotopoulos (Caltech Math)

Abstract: A big part of mathematical activity revolves around classification problems. However, not every classification problem has a satisfactory solution, and some classification problems are more complicated than others. Dynamical properties such as generic ergodicity and turbulence are crucial in the development of a rich complexity theory for classification problems. In this talk we will review some of the existing anti-classification techniques and we will introduce a new obstruction for classification by orbit equivalence relations of TSI Polish groups; a topological group is TSI if it admits a compatible two side invariant metric. We will then show that the Wreath product of any two non-compact subgroups of $S_{\infty}$ admits an action whose orbit equivalence relation is generically ergodic with respect to orbit equivalence relations of TSI group actions.
This is joint work with Shaun Allison.

4:00 pm in TBA,Friday, April 3, 2020