Department of

# Mathematics

Seminar Calendar
for Analysis Seminar events the year of Sunday, May 16, 2021.

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events for the
events containing

More information on this calendar program is available.
Questions regarding events or the calendar should be directed to Tori Corkery.
      April 2021              May 2021              June 2021
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1  2  3                      1          1  2  3  4  5
4  5  6  7  8  9 10    2  3  4  5  6  7  8    6  7  8  9 10 11 12
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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.

Friday, March 5, 2021

2:00 pm in Contact for zoom link,Friday, March 5, 2021

#### $L^{2}$ decoupling: An Introduction and Applications

###### Ryan McConnell (UIUC Math)

Abstract: Suppose one wants to decompose a function on into parts that have disjoint Fourier supports. Due to linearity of the Fourier transform, the sum of these parts must be the original function. Suppose, however, that you wish to understand how the norms of these parts relates to the norm of the original function. While this task isn’t so straight forward, Bourgain and Demeter (2015) were able to resolve a conjecture related to this: the $L^{2}$ Decoupling Conjecture.In this talk we will introduce the conjecture, provide applications of it to both PDEs and Number Theory, prove an earlier result of Bourgain for a smaller range of admissible exponents, and (time permitting) comment on how to adapt the ideas presented to prove the full result.

Friday, March 12, 2021

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

#### Circle Packings and a discrete Riemann Mapping Theorem

###### Kesav Krishnan (UIUC Math)

Abstract: I will introduce Circle Packings as defined by Thurston, and describe how they provide a discrete analogue of complex analysis and conformal maps. I will also introduce the discrete analogue of the Riemann Mapping Theorem, and if time permits I will talk about how discrete complex function theory plays a crucial role in certain 2-dimensional models in probability theory.

Friday, March 19, 2021

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

#### The descriptive complexity of classes of Banach lattices

###### Mary Angelica Gramcko-Tursi (UIUC Math)

Abstract: The descriptive complexity of a class of spaces gives us an initial sense of how "nice" the class is. When a set is not "nice," this fact can also be used to derive results related to the existence of universal spaces. In this talk, we present some examples of Borel and non-Borel classes of Banach lattices and some related results derived from their descriptive complexity. We also show areas where the descriptive complexity results on Banach lattices compare and contrast with previously done analogous work on Banach spaces.

Friday, April 2, 2021

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

Abstract: TBA