Seminar Calendar
for events the week of Tuesday, September 2, 2014.

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More information on this calendar program is available.
Questions regarding events or the calendar should be directed to Tori Corkery.
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Tuesday, September 2, 2014

Logic Seminar
1:00 pm   in 345 Altgeld Hall,  Tuesday, September 2, 2014
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Submitted by ssolecki.
Kostya Slutsky (UIC)
Regular cross-sections of Borel flows
Abstract: A cross-section of a Borel flow is a Borel set that has countable intersection with each orbit of the flow. We shall be interested in constructing cross-sections with a prescribed set of possible distances between adjacent points within orbits. The main result of the talk is that given any two rationally independent positive reals and a free Borel flow one can always find a cross-section with distances between adjacent points being only these two real numbers. We shall give an overview of the subject from both ergodic theoretical and descriptive points of view and an application of the above result to orbit equivalence of flows will be presented.

Geometry, Groups and Dynamics/GEAR Seminar
1:00 pm   in Altgeld Hall 243,  Tuesday, September 2, 2014
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Submitted by kapovich.
Jenya Sapir (UIUC Math)
Counting non-simple closed curves on surfaces
Abstract: We show how to get coarse bounds on the number of (non-simple) closed geodesics on a surface, given upper bounds on both length and self-intersection number. Recent work by Mirzakhani and by Rivin has produced asymptotics for the growth of the number of simple closed curves and curves with one self-intersection (respectively) with respect to length. However, no asymptotics, or even bounds, were previously known for other bounds on self-intersection number. Time permitting, we will discuss some applications of this result. [The talk can be seen on YouTube at http://youtu.be/QmbSUWtPxP0 ]

Harmonic Analysis and Differential Equations
1:00 pm   in 347 Altgeld Hall,  Tuesday, September 2, 2014
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Submitted by berdogan.
Samantha Xu (UIUC Math)
To Be Announced

Graph Theory and Combinatorics Seminar
3:00 pm   in 241 Altgeld Hall,  Tuesday, September 2, 2014
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Submitted by molla.
Jozsef Balogh   [email] (UIUC Math)
On the applications of counting independent sets in hypergraphs
Abstract: Recently, Balogh-Morris-Samotij and Saxton-Thomason developed a method of counting independent sets in hypergraphs. During the talk, I show a recent application of the method; solving the following Erdos problem: What is the number of maximal triangle-free graphs? If there is some extra time in the talk, I will survey some other recent applications. Note that despite similar abstracts in the past, the talk is significantly new. These applications are partly joint with Shagnik Das, Michelle Delcourt, Hong Liu, Richard Mycroft, Sarka Petrickova, Maryam Sharifzadeh and Andrew Treglown.

Wednesday, September 3, 2014

Graduate Student Algebraic Geometry Seminar
2:00 pm   in 441 Altgeld Hall,  Wednesday, September 3, 2014
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Submitted by fieldst2.
Nathan Fieldsteel   [email] (UIUC Math)
An Introduction to Arithmetic Geometry: Part II
Abstract: A continuation of last week's talk, we will continue the discussion of geometry over finite fields, covering $q$-binomial coefficients, connections to algebraic combinatorics, and $\mathbb{F}_1$ geometry.

Math 499: Introduction to Graduate Mathematics
4:00 pm   in 245 Altgeld Hall,  Wednesday, September 3, 2014
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Submitted by laugesen.
Zoi Rapti (Department of Mathematics, University of Illinois at Urbana-Champaign)
Host mortality and disease spread
Abstract: We will introduce a coupled PDE-ODE system that describes the interactions between the susceptible (S) and infected (I) hosts, the pathogen (Z) that affects them and the food resource (A) of both classes of hosts. The model is a 4-dimensional system of 3 ODES and 1 PDE. We are interested in investigating the effect of host mortality (such as background mortality, disease induced mortality, predation) on the disease dynamics (equilibrium vs. oscillations) and metrics of disease such as the basic reproductive number R0 and prevalence. We will discuss the stability and bifurcations of the system and show that the interplay among the various types of mortality generates interesting behavior in our model. All biological terms will be defined, so no prior knowledge from biology is required. Introductory graduate ODE and PDE courses suffice for this talk.

Thursday, September 4, 2014

Number Theory Seminar
11:00 am   in 241 Altgeld Hall,  Thursday, September 4, 2014
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Submitted by ford.
R. Sujatha (Univ. British Columbia)
Elliptic curves, modular forms, Hida families
Abstract: Iwasawa theory provides a unifying strand that allows for a study of the Galois representations arising from elliptic curves and modular forms. The invariants arising from this study provides useful information on concrete problems like the study of rational points of elliptic curves. In this talk, we shall explain how some of these techniques can be extended to study Iwasawa theory of Hida families over non-commutative $p$-adic Lie extensions.

Geometry, Groups and Dynamics/GEAR Seminar
1:00 pm   in Altgeld Hall 243,  Thursday, September 4, 2014
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Submitted by kapovich.
Michael Hull (University of Illinois at Chicago)
Acylindrically hyperbolic groups and small cancellation quotients
Abstract: We will discuss the class of acylindrically hyperbolic groups, a generalization of hyperbolic and relatively hyperbolic groups which includes mapping class groups, $Out(F_n)$ and many other examples. In particular, we will discuss certain generalizations of small cancellation theory to the class of acylindrically hyperbolic groups and the properties and applications of the associated quotient groups. [The talk can be seen on YouTube at http://youtu.be/qUHQnkGUFvA ]

Commutative Ring Theory Seminar
3:00 pm   in 243 Altgeld Hall,  Thursday, September 4, 2014
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Submitted by mastroe2.
Organizational Meeting

Mathematics Colloquium
4:00 pm   in 245 Altgeld Hall,  Thursday, September 4, 2014
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Submitted by seminar.
R. Sujatha (University of British Columbia)
Motives and Birational Geometry
Abstract: The theory of motives has been a strong inspiring force for mathematical research in the last few decades. We shall discuss a categorical approach to the construction of birational motives and its implications for study of functors that are birational in nature. This is joint work with Bruno Kahn.

Friday, September 5, 2014

Applying to Graduate School
3:00 pm   in 245 Altgeld Hall,  Friday, September 5, 2014
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Submitted by laugesen.
Richard Laugesen, Director of Graduate Studies in Mathematics   [email] (UIUC Math)
Information Session
Abstract: Information session for undergraduates interested in applying to Mathematics graduate programs in the United States. (Not specific to U of Illinois.) Come and ask about GREs, TOEFL, personal statements, letters of recommendation, public vs. private universities, and more.

Algebra, Geometry, and Combinatorics
4:00 pm   in 343 Altgeld Hall,  Friday, September 5, 2014
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Submitted by redavid2.
Oliver Pechenik   [email] (UIUC Math)
To Be Announced