Seminar Calendar
for events the week of Wednesday, October 1, 2014.

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events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
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Monday, September 29, 2014

Opeator Algebra Learning Seminar
5:00 pm   in 141 Altgeld Hall,  Monday, September 29, 2014
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Submitted by mjunge.
 Marius JungeAGMAbstract: AGM2

Tuesday, September 30, 2014

Corporate Forum
9:00 am   in Illini Rooms A & B, Illini Union,  Tuesday, September 30, 2014
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Submitted by seminar.
 Corporate ForumAbstract: The Corporate Forum will be held from 9 a.m. to 4 p.m. The Career Fair will run throughout the day with company presentations given concurrently.

Topology Seminar
11:00 am   in 243 Altgeld Hall,  Tuesday, September 30, 2014
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Submitted by cmalkiew.
 Cary Malkiewich   [email] (UIUC)Coassembly in algebraic K-theoryAbstract: The coassembly map allows us to approximate any contravariant homotopy-invariant functor by an excisive functor, i.e. one that behaves like a cohomology theory. We apply this construction to a contravariant form of Waldhausen's algebraic K-theory of spaces, and its corresponding THH functor. The results are somewhat surprising: a certain dual form of the A-theory Novikov conjecture is false, but when the space in question is the classifying space BG of a finite p-group, coassembly on THH is split surjective after p-completion. The method of proof suggests new conjectures about both the assembly and coassembly maps for the A-theory of BG. If there is time, we will also discuss related work on the equivariant structure of THH.

Logic Seminar
1:00 pm   in 345 Altgeld Hall,  Tuesday, September 30, 2014
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Submitted by phierony.
 Will Boney (UIC)Tameness in Abstract Elementary ClassesAbstract: Tameness is a locality property of Galois types in AECs. Since its isolation by Grossberg and VanDieren 10 years ago, it has been used to prove new results (upward categoricity transfer, stability transfer) and replace set-theoretic hypotheses (existence of independence notions). In this talk, we will outline the basic definitions, summarize some key results, and discuss some open questions related to tameness.

Geometry, Groups and Dynamics/GEAR
1:00 pm   in 243 Altgeld Hall,  Tuesday, September 30, 2014
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Submitted by jathreya.
 Jerome Rousseau (Universidade Federal da Bahia/Illinois)Hitting time statistics for observations and application to random dynamical systemsAbstract: We study the distribution of hitting and return times for observations of dynamical systems. We apply this results to get an exponential law for the distribution of hitting and return time for rapidly mixing random dynamical systems. For random subshifts of finite type, we analyze the distribution of hitting times with respect to the sample measures and prove that under fast mixing assumptions one can get an exponential law. View lecture at http://youtu.be/tN0jpVRCkfU

Probability Seminar
2:00 pm   in Altgeld Hall 347,  Tuesday, September 30, 2014
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Submitted by kkirkpat.
 Zoran Vondracek (UIUC Math and University of Zagreb)A distributional equality for suprema of spectrally positive Levy processesAbstract: Let Y be a spectrally positive Levy process with strictly negative expectation, C an independent subordinator with finite expectation, and X=Y+C. A curious distributional equality proved some ten years ago states that if the expectation of X is strictly negative, then the overall supremum of Y and the supremum of X just before the first time its new supremum is reached by a jump of C have the same distribution. In this talk I will give an alternative proof of an extension of this result and offer an explanation why it is true.

Algebraic Geometry Seminar
3:00 pm   in 243 Altgeld Hall,  Tuesday, September 30, 2014
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Submitted by katz.
 Steve Bradlow (UIUC Math)Higgs bundles, spectral data, and fiber products of curvesAbstract: I will discuss some interesting relations among Higgs bundles, from the point of view of spectral data, that result from isogenies among low dimensional Lie groups. This will be a report on work in progress with Laura Schaposnik. The secret goal of the talk is to describe the various components that enter in the relations clearly enough so that the algebraic geometry experts in the audience can help me and Laura make sense of it all.

Graph Theory and Combinatorics Seminar
3:00 pm   in 241 Altgeld Hall,  Tuesday, September 30, 2014
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Submitted by molla.
 Michael Santana   [email] (UIUC Math)On the strong chromatic index of graphsAbstract: A strong edge-coloring of a graph $G$ is a proper edge-coloring with the additional property that each color class forms an induced matching in $G$. The strong chromatic index of $G$ is the minimum $k$ for which $G$ has a strong edge-coloring using $k$ colors. Erdős and Nešetřil conjectured that every graph with maximum degree $\Delta$ has strong chromatic index at most $\frac{5}{4}\Delta^2$ if $\Delta$ is even, and at most $\frac{5}{4}\Delta^2 - \frac{1}{2}\Delta + \frac{1}{4}$ if $\Delta$ is odd. If true, both cases are best possible. In 1990, Faudree, Gyárfás, Schelp, and Tuza revised this conjecture of Erdős and Nešetřil for planar graphs with maximum degree at most 3, stating that such graphs should have strong chromatic index at most 9. We verify this conjecture, which is best possible, and extend it to loopless multigraphs. In addition to our result, I will present several unresolved conjectures and areas for further research. This is joint work with A.V. Kostochka, X. Li, W. Ruksasakchai, T. Wang, and G. Yu.

Actuarial Science & Financial Mathematics
4:00 pm   in 2 Illini Hall,  Tuesday, September 30, 2014
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Submitted by rfeng.
 Dr. Kannoo Ravindran (Annuity Systems Inc.)Variable Annuities: The Good, Bad and The UglyAbstract: The first version of Variable Annuities (VAs) appeared in 1952 by the courtesy of TIAA-CREF. Since then, the features inherent in VAs have morphed as insurance companies’ attitudes towards risks, profitability, product customization, market share, required capital etc. changed. In this talk, I will touch on this development and describe the lay of the land as it relates to VAs and Fixed Indexed Annuities (FIAs) as it stands today. In addition to this, I will also discuss the convergence in the thinking between the capital markets and the actuarial community as it related to valuing the risks underlying these products. The talk will conclude with an overview of some of the theoretically challenging problems that practitioners still struggle with on a daily basis.

Wednesday, October 1, 2014

Probability Seminar
2:00 pm   in 443 Altgeld Hall,  Wednesday, October 1, 2014
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Submitted by rsong.
 Xicheng Zhang (Wuhan University Math)Fundamental solution of kinetic Fokker-Planck operator with anisotropic nonlocal dissipativityAbstract: By using a probability approach (the Malliavin calculus), we prove the existence of smooth fundamental solutions for degenerate kinetic Fokker-Planck equation with anisotropic nonlocal dissipativity, where the dissipative term is the generator of an anisotropic L\'evy process, and the drift term is allowed to be cubic growth.

2:00 pm   in 441 Altgeld Hall,  Wednesday, October 1, 2014
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Submitted by fieldst2.
 Eliana Duarte   [email] (UIUC Math)What are Rees algebras?Abstract: The study of Rees algebras plays an important role in the implicitization problem for maps between projective spaces. In this talk I will define the Rees algebra of an ideal in a commutative ring and explain its relation to implicitization of curves and surfaces. All of the concepts just mentioned will be defined and illustrated with friendly examples.

Integrability and Representation Theory
3:00 pm   in 347 Altgeld Hall,  Wednesday, October 1, 2014
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Submitted by rinat.
 Milen Yakimov (Louisiana State University)Maximal green sequences for cluster algebra structures on double Bruhat cellsAbstract: Maximal green sequences of cluster mutations were introduced by Keller for the purposes of applications to quantum Donaldson-Thomas invariants, and by string theorists for the study of BPS spectra. It is conjectured that they are in bijection with discrete stability conditions with finitely many stables on the corresponding cluster category (under certain identifications). We will prove that maximal green sequences exist for all Berenstein-Fomin-Zelevinsky cluster algebras associated to double Bruhat cells in arbitrary simple Lie groups. This is a large class of cluster algebras that plays an important role in Lie theory.

Math 499: Introduction to Graduate Mathematics
4:00 pm   in 245 Altgeld Hall,  Wednesday, October 1, 2014
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Submitted by laugesen.
 Ely Kerman (Department of Mathematics, University of Illinois at Urbana-Champaign)An Introduction to Symplectic TopologyAbstract: Mechanical systems which preserve energy also preserve volumes in phase space. In 1890 Poincar\'e exploited this property to prove his famous recurrence theorem. In fact these mechanical systems preserve a more subtle "symplectic" structure which corresponds to the measurement of certain two-dimensional areas. The consequences of this latter preservation lie at the heart of symplectic topology. They are varied and easily described but are usually very difficult to prove. In this talk I will describe several of the remarkable theorems of symplectic topology, like Gromov's Nonsqueezing Theorem, outline the ideas involved in their proof and hopefully mention some open questions including a conjectured generalization of Poincar\'e's recurrence theorem.

Thursday, October 2, 2014

10:00 am   in 143 Altgeld Hall,  Thursday, October 2, 2014
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Submitted by ackrmnn2.
 Erin Compaan (UIUC Math)Well-Posedness Results for the Majda-Biello SystemAbstract: The Majda-Biello system, consisting of coupled KdV-type equations, has been proposed as a model for certain long-wavelength atmospheric waves. The well-posedness of the system has been studied by Tadahiro Oh. It turns out that the system is well-posed in Sobolev spaces of sufficiently high index, where "sufficiently high" depends on the properties of the coupling parameter. This talk will discuss his results and provide a high-level overview of the proofs.

Number Theory Seminar
11:00 am   in 241 Altgeld Hall,  Thursday, October 2, 2014
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Submitted by astraub.
 Harold Diamond   [email] (UIUC Math)Bounds for the logarithmic derivative of the Euler Gamma functionAbstract: We derive bounds for the logarithmic derivative of the Euler Gamma function. The only facts assumed are the first few terms of the asymptotic expansion and the functional equation of Gamma. The proof involves a backward induction.

Math-Physics Seminar
12:30 pm   in 464 Loomis Laboratory,  Thursday, October 2, 2014
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Submitted by katz.
 Sumit Das (Kentucky Physics)Scaling in Holographic Quantum Quench Abstract: In recent years the problem of quantum quench in the vicinity of critical points  has been investigated using holographic methods. This has led to an understanding of decoupling of length scales in the dynamics of slow quench  and the emergence of Kibble-Zurek scaling, and provided predictions for corrections to the leading scaling behavior. In the other limit, holographic calculations have led to the discovery of new scaling laws for fast quench, which have been subsequently shown to be generic properties of deformations  of any conformal field theory regardless of holography. This talk will discuss the salient aspects of this development.

2:00 pm   in 007 Illini Hall,  Thursday, October 2, 2014
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Submitted by amalik10.
 Kyle Pratt (UIUC Math)Special Sets of PrimesAbstract: We discuss special'' sets of primes in the integers, or sets of primes whose members satisfy interesting conditions. We are often interested in whether special sets of primes are infinite, but these questions are usually very difficult. We discuss how the existence of certain infinite special sets of primes would resolve a conjecture of Carmichael on the Euler totient function. We formulate similar questions for sets of primes in $\mathbb{F}_q[x]$ and discuss relevant recent joint work.

Mathematics Colloquium
4:00 pm   in 245 Altgeld Hall,  Thursday, October 2, 2014
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Submitted by seminar.
 Tandy Warnow (Departments of Bioengineering and Computer Science, University of Illinois)New methods for inferring species trees in the presence of incomplete lineage sortingAbstract: Estimating the Tree of Life will likely involve a two-step procedure, where in the first step trees are estimated on many genes, and then the gene trees are combined into a tree on all the taxa. However, the true gene trees may not agree with with the species tree, due to biological processes such as deep coalescence, gene duplication and loss, and horizontal gene transfer. Statistically consistent methods based on the multi-species coalescent model have been developed to estimate species trees in the presence of incomplete lineage sorting; however, the relative accuracy of these methods compared to the usual "concatenation" approach is a matter of substantial debate within the systematic biology research community. In this talk, I will present results showing that coalescent-based estimation methods are impacted by gene tree estimation error, so that they can be less accurate than concatenation in many cases. I will also present new methods for estimating species trees in the presence of gene tree conflict due to ILS that are more accurate than current methods. Key to these methods is addressing gene tree estimation error more effectively. I will also present results using these techniques to estimate species tree for birds and for plants.

Actuarial Science & Financial Mathematics
4:00 pm   in 2 Illini Hall,  Thursday, October 2, 2014
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Submitted by rfeng.
 John Manistre (GGY AXIS)Down but not Out: A Cost of Capital Approach to Fair Value Risk MarginsAbstract: The Market Cost of Capital approach is emerging as a standard for estimating risk margins for non-hedgeable risk on an insurer’s fair value balance sheet. This paper develops a conceptually rigorous formulation of the cost of capital method for estimating margins for mortality, lapse, expense and other forms of underwriting risk. For any risk situation we develop a three step modeling approach which starts with i) a best estimate model and then adds ii) a static margin for contagion risk (the risk that current experience differs from the best estimate) and iii) a dynamic margin for parameter risk (the risk that the best estimate is wrong and must be revised). We show that the solution to the parameter risk problem is fundamentally a regime switching model which can be solved by Monte Carlo simulation. The paper then goes on to develop a number of more pragmatic methods which can be thought of as short cut approximations to the first principles model. One of these short cuts is the Prospective method currently used in Europe. None of these methods require stochastic on stochastic projections to get useful results.

Friday, October 3, 2014

Algebra, Geometry and Combinatorics
4:00 pm   in 343 Altgeld Hall,  Friday, October 3, 2014
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Submitted by redavid2.
 Abraham Martín del Campo   [email] (IST Austria)Numerical computations and Galois groups in Schubert calculusAbstract: Schubert calculus is an important class of geometric problems involving linear spaces meeting other fixed but general linear spaces. Problems in Schubert calculus can be modeled by systems of polynomial equations. Thus, we can use numerical methods to find the solutions to these geometrical problems. We present a Macaulay2 implementation of numerical algorithms that solve Schubert problems. These algorithms are based on the geometric Pieri and Littlewood-Richardson homotopies. We use our implementation to study Galois groups of Schubert problems. This work is partially joint with Anton Leykin and Frank Sottile.