Department of

# Mathematics

Seminar Calendar
for Graduate Analysis Seminar events the year of Friday, January 15, 2021.

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events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
    December 2020           January 2021          February 2021
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1  2  3  4  5                   1  2       1  2  3  4  5  6
6  7  8  9 10 11 12    3  4  5  6  7  8  9    7  8  9 10 11 12 13
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Friday, February 12, 2021

2:00 pm in Contact for zoom link,Friday, February 12, 2021

#### The Largest Sum-free Subsets of Integers and its Generalization

###### Shukun Wu (UIUC Math)

Abstract: An old conjecture in additive combinatorics asks: what is the largest sum-free subset of any set of N positive integers? Here the word "largest" should be understood in terms of cardinality. For example, the largest sum-free subset of the first N positive integers has cardinality [(N+1)/2], which is the number of odd integers smaller than N, as well as the number of integers that lie in the interval [N/2,N]. In this talk, I will discuss a special case of the sum-free conjecture and the analogous conjecture on (k,l)-sum-free sets. This is a joint work with Yifan Jing

Friday, February 19, 2021

2:00 pm in Contact for zoom link,Friday, February 19, 2021

#### Expanding Thurston Maps and Visual Spheres

###### Stathis Chrontsios (UIUC Math)

Abstract: Complex Dynamics study iterations of entire functions and/or rational maps. While doing so in the latter case, the properties of the Riemann sphere are being used (e.g. conformal structure). In this talk, the protagonists will be Thurston maps, generalizations of rational maps that are defined on topological spheres. Connections with their complex analytic counterparts will be discussed, as well as questions from a metric-analytic point of view about visual spheres, the metric spaces the dynamics of these maps induce.

Friday, February 26, 2021

2:00 pm in Contact for zoom link,Friday, February 26, 2021

#### Minimizing Eigenvalues of the Laplacian

###### Scott Harman (UIUC Math)

Abstract: pectral theory is concerned with studying the eigenvalues of partial differential operators. The most canonical example is the second order Laplacian . In this talk, we are concerned mostly with minimizing eigenvalues of the Laplacian on a bounded domain with and has zero boundary condition. To phrase it another way, what shape of domain will yield the smallest frequencies? We will give a brief overview of spectral theory, a proof of the Faber-Krahn inequality which states the ball minimizes the first eigenvalue, and conjectures for higher eigenvalues and the shape of the domain in the limiting case.