MSCS Seminar Calendar

Saturday October 22, 2016
RTG Workshop on the Geometry and Physics of Higgs bundles I
8:30 a.m. - 7 p.m.
Mini-courses by Marina Logares (Oxford) & Steven Rayan (Saskatchewan)
8:30 AM in SEO 430
For more information on the schedule, and social plans see the website: http://schapos.people.uic.edu/Higgs-2016.html If you would like to register, email schapos@uic.edu

Set theory workshop
Iterated forcing and the Continuum Hypothesis, part 3
Justin Moore (Cornell)
9:30 AM in SEO 636
One of the great successes in set theory in the 1970s and 80s has been the isolation of an optimal hypothesis for iterating forcings while preserving uncountablity. It turns out that while there is a well developed theory of iterating forcings which do not introduce new reals, this theory is necessarily more ad hoc in nature. This tutorial will discuss Shelah's preservation theorems for not adding reals as well as recently discovered examples which illustrate that these results are, in some sense, sharp.

Set theory workshop
Integer cost and ergodic actions
Anush Tserunyan (UIUC)
11:00 AM in SEO 636
A countable Borel equivalence relation $E$ on a probability space can always be generated in two ways: as the orbit equivalence relation of a Borel action of a countable group and as the connectedness relation of a locally countable Borel graph, called a $\it{graphing}$ of $E$. Assuming that $E$ is measure-preserving, graphings provide a numerical invariant called $\it{cost}$, whose theory has been largely developed and used by Gaboriau and others in establishing rigidity results. A well-known theorem of Hjorth states that when $E$ is ergodic, treeable (admits an acyclic graphing), and has integer or infinite cost $n \le \infty$, then it is generated by an a.e. free measure-preserving action of the free group $\mathbf{F}_n$ on $n$ generators. We give a simpler proof of this theorem and the technique of our proof, combined with two other new tools, yields a strengthening of Hjorth's theorem: the action of $\mathbf{F}_n$ can be arranged so that each of the $n$ generators acts ergodically. This is joint work with Benjamin Miller.

Set theory workshop
Applications of descriptive set theory to classical dynamical systems, part 1
Matt Foreman (UC Irvine)
1:30 PM in SEO 636
In 1932 von Neumann proposed the project of classifying smooth measure preserving transformations. As part of the project he raised the question of whether every ergodic measure preserving transformation of the unit interval is isomorphic to a diffeomorphism of a manifold. Despite deep progress on both questions, they remained open until recently. The lecture presents joint work with B. Weiss that shows that the classification problem is impossible to solve--because the associated equivalence relation is not Borel (and moreover is strictly more complicated than any $S^\infty$-action). Along the way the authors made progress on the second problem, by showing that a quasi-generic class of transformations can be realized as diffeomorphisms of the 2-torus. This class is the source of the complexity of the classification problem.

Set theory workshop
Applications of descriptive set theory to classical dynamical systems, part 2
Matt Foreman (UC Irvine)
2:45 PM in SEO 636
In 1932 von Neumann proposed the project of classifying smooth measure preserving transformations. As part of the project he raised the question of whether every ergodic measure preserving transformation of the unit interval is isomorphic to a diffeomorphism of a manifold. Despite deep progress on both questions, they remained open until recently. The lecture presents joint work with B. Weiss that shows that the classification problem is impossible to solve--because the associated equivalence relation is not Borel (and moreover is strictly more complicated than any $S^\infty$-action). Along the way the authors made progress on the second problem, by showing that a quasi-generic class of transformations can be realized as diffeomorphisms of the 2-torus. This class is the source of the complexity of the classification problem.

Set theory workshop
Weak Squares and Very Good Scales
Maxwell Levine (UIC)
4:00 PM in SEO 636
The combinatorial properties of large cardinals tend to clash with those satisfied by G\"odel's constructible universe, especially the square property (denoted $\square_\kappa$) isolated by Jensen in the seventies. Strong cardinal axioms refute the existence of square, but it is possible with some fine-tuning to produce models that exhibit some large cardinal properties together with weakenings of square. In this talk we will exhibit some results along these lines and will outline the techniques used to produce them.
Sunday October 23, 2016
RTG Workshop on the Geometry and Physics of Higgs bundles I
8:30 a.m. - 1 p.m.
Mini-courses by Marina Logares (Oxford) & Steven Rayan (Saskatchewan)
8:30 AM in SEO 430
For more information on the schedule, and social plans see the website: http://schapos.people.uic.edu/Higgs-2016.html If you would like to register, email schapos@uic.edu

Set theory workshop
Applications of descriptive set theory to classical dynamical systems, part 3
Matt Foreman (UC Irvine)
10:00 AM in SEO 636
In 1932 von Neumann proposed the project of classifying smooth measure preserving transformations. As part of the project he raised the question of whether every ergodic measure preserving transformation of the unit interval is isomorphic to a diffeomorphism of a manifold. Despite deep progress on both questions, they remained open until recently. The lecture presents joint work with B. Weiss that shows that the classification problem is impossible to solve--because the associated equivalence relation is not Borel (and moreover is strictly more complicated than any $S^\infty$-action). Along the way the authors made progress on the second problem, by showing that a quasi-generic class of transformations can be realized as diffeomorphisms of the 2-torus. This class is the source of the complexity of the classification problem.

Set theory workshop
Space decomposition techniques in Borel dynamics
Kostyantyn Slutskyy (UIC)
11:30 AM in SEO 636
In recent years a substantial progress has been achieved in the field of Borel dynamics. A part of this progress is due to the development of space decomposition methods. The goal of the talk is to make an overview of the old and new results that have been proved along this path. In particular, we will discuss in various degrees of details the following: Dougherty-Jackson-Kechris classification of hyperfinite Borel equivalence relations, Multi-Tower Rokhlin Lemma for Borel automorphisms and regular cross sections of Borel flows, Lebesgue orbit equivalence of multidimensional flows, and Hochman's proof of existence of finite generators for compressible automorphisms.
Monday October 24, 2016
The Haar measure on compact groups
Keaton Quinn (UIC)
12:00 PM in SEO 1227
We prove the existence and uniqueness of the Haar measure in the case of compact groups.

Circle Packings and Complex Projective Surfaces
Ellie Dannenberg (UIC)
1:00 PM in SEO 636
The Koebe-Andreev-Thurston Circle Packing Theorem says that given a triangulation $\tau$ of a surface $S$, there is a unique pair $(g,P)$, where $g$ is a constant curvature Riemannian Metric on $S$. $P$ is a circle packing of circles with respect to $g$ and combinatorics given by $\tau$. If, instead of constant curvature Riemannian metrics on $S$, we consider complex projective structures on $S$, there is a deformation space of complex projective circle packings with fixed combinatorics.
In this talk, I'll discuss circle packings and complex projective structures on surfaces. I'll then discuss the deformation space of complex projective circle packings with combinatorics given by $\tau$. Much is still unknown about this space.

Commutative Algebra Seminar
-
No Seminar (-)
1:00 PM in SEO 427

Class Field Theory Seminar
TBA
Ramin Takloo-Bighash
2:00 PM in SEO 1227

Geometry, Topology and Dynamics Seminar
Quivers, hyperpolygons, and Hitchin systems
3:00 PM in SEO 636
I will discuss three closely-related moduli problems: moduli of representations of star-shaped quivers, moduli of hyperpolygons, and moduli of parabolic Higgs bundles. One theme that weaves these three problems together is complete integrability. I will discuss recent results on the topology of these moduli spaces (joint work with Jonathan Fisher) and then pose questions on the relationship between stability for Higgs bundles and stability for hyperpolygons, and also speculate on mirror symmetry for hyperpolygon spaces.
We will be going for lunch on Monday 1-2, have some tasty treats for tea at 3 p.m. right before the talk.

Dissertation Defense
The Critical Orbit Structure of Quadratic Polynomials in Zp
Cara Mullen
4:00 PM in SEO 1227

Analysis and Applied Mathematics Seminar
Existence of large-amplitude steady stratified water waves
Ming Chen (University of Pittsburgh)
4:00 PM in SEO 636
We consider 2D steady water waves with heterogeneous density. The presence of stratification allows for a wide variety of traveling waves, including fronts, so-called generalized solitary waves with ripples in the far field, and even fronts with ripples! Among these many possible wave patterns, we prove that for any smooth choice of upstream velocity and monotone streamline density function, there always exists a continuous curve of solitary waves with large amplitude, which are even and decreasing monotonically on either side of a central crest. As one moves along this curve, the horizontal fluid velocity comes arbitrarily close to the wave speed.
We will also discuss a number of results characterizing the qualitative features of solitary stratified waves. In part, these include bounds on the Froude number from above and below that are new even for constant density flow; an a priori bound on the velocity field and lower bound on the pressure; a proof of the nonexistence of monotone bores for stratified surface waves; and a theorem ensuring that all supercritical solitary waves of elevation have an axis of even symmetry. This is a joint work with Samuel Walsh and Miles Wheeler.
Tuesday October 25, 2016
Logic Seminar
The Hanf number for Extendability
John Baldwin (UIC)
4:00 PM in SEO 427
We construct a complete $L_{\omega_1,\omega}$-sentence $\phi$ such that $(\textbf{R},\subseteq)$ is an abstract elementary class with a proper class of models.
Theorem. There is a maximal model $M \in \textbf{R}$ of cardinality $\lambda$ if there is no measurable cardinal $\rho$ with $\rho \leq \lambda$, $\lambda = \lambda^{< \lambda}$, and there is an $S \subseteq S^{\lambda}_{\aleph_0}$, that is stationary non-reflecting, and $\diamond_S$ holds.
Thus in the absence of a measurable, $\phi$ has arbitrarily large maximal models. But in the presence of measurables there are maximal models cofinally in the first measurable and never again. I hope to say something about the removal of the set-theoretic hypotheses.
Wednesday October 26, 2016
Oral Practice
Yi Hua (Oral Practice)
3:00 PM in SEO 512
Oral practice for Yi Hua

Algebraic Geometry Seminar
Correspondences between convex geometry and complex geometry
Jian Xiao (Northwestern University)
4:00 PM in SEO 427
We present several (new) correspondences between convex bodies and the theory of holomorphic line bundles on smooth projective varieties or Kähler manifolds, thus extending the dictionary between convex geometry and complex geometry. An important ingredient is a refined structure of the movable cone of curves. This is joint work with Brian Lehmann.

Statistics Seminar
Design and Analysis of Clinical Studies using Restricted Mean Survival Time
Lihui Zhao (Northwestern University)
4:00 PM in SEO 636
For a study with an event time as the endpoint, its survival function contains all the information regarding the temporal, stochastic profile of this outcome variable. The survival probability at a specific time point, say t, however, does not transparently capture the temporal profile of this endpoint up to t. An alternative is to use the restricted mean survival time (RMST) at time t to summarize the profile. The RMST is the mean survival time of all subjects in the study population followed up to t, and is simply the area under the survival curve up to t. The advantages of using such a quantification over the survival rate have been discussed in the setting of a fixed-time analysis. In this research, we generalize this approach by considering a curve based on the RMST over time as an alternative summary to the survival function. Inference, for instance, based on simultaneous confidence bands for a single RMST curve and also the difference between two RMST curves are proposed. The latter is informative for evaluating two groups under an equivalence or noninferiority setting, and quantifies the difference of two groups in a time scale. In addition, we extend RMET to the setting of multiple endpoints, which includes classical competing risks and semi-competing risks. The methods are illustrated with the data from two clinical trials.
Thursday October 27, 2016
Louise Hay Logic Seminar
TBA
Hunter Chase (UIC)
4:00 PM in SEO 427
Friday October 28, 2016
Homotopy Theory Seminar
TBD
Tasos Moulinos (UIC)
12:30 PM in SEO 1227

Commutative Algebra Seminar
F-signature of non-local rings
Thomas Polstra (University of Missouri)
1:00 PM in SEO 427
The F-signature of a local ring, a numerical invariant shown to exist by Tucker, is the asymptotic measurement of the number of Frobenius splittings for which a local ring of prime characteristic admits. The F-signature serves as a measurement of singularities. Most notably, the F-signature of a local ring is 1 if and only if the ring is regular, by work of Huneke and Leuschke, and the F-signature of a local ring is positive if and only if the ring is strongly F-regular, by work of Aberbach and Leuschke. We will discuss how the notion and existence of F-signature extends to all rings which are F-finite but not necessarily local. Our methods our made meaningful by extending Huneke's and Leuschke's and Aberbach's and Leuschke's theorems to the non-local case. This is based on joint work with Alessandro De Stefani and Yongwei Yao.

Logic Seminar
Model-theoretic characterizations of large cardinals
Will Boney (Harvard University)
2:00 PM in SEO 427
We discuss some characterizations of large cardinals using model theory, especially around compactness in $\mathbb{L}_{\kappa, \kappa}$.
Monday October 31, 2016
Commutative Algebra Seminar
Cartier modules and crystals
Nicholas Switala (UIC)
1:00 PM in SEO 427
The goal of this talk is to introduce the categories of Cartier modules and Cartier crystals introduced by M. Blickle and G. Boeckle in their 2011 Crelle paper, as well as the basic finiteness results proved there.

Geometry, Topology and Dynamics Seminar
Molino theory for laminations
Olga Lukina (UIC)
3:00 PM in SEO 636
A foliation of a compact manifold can be considered as a generalized dynamical system, in the sense of Smale. The study of the dynamical properties of foliations has been an active area of research for the past 40 years. A smooth foliation is Riemannian, if the normal bundle of the foliation admits a Riemannian metric invariant under the action of the holonomy pseudogroup of the foliation. Riemannian foliations are very rigid geometric structures, and they are completely classified by Molino theory.
Ghys asked in 1988 whether Molino theory can be generalized to a topological setting. In this setting, one considers foliations of compact topological spaces, which do not admit normal bundles, and where the transversals need not be locally connected. The condition analogous to the existence and invariance of a Riemannian metric in this non-differentiable setting, is the assumption of equicontinuity of the holonomy pseudogroup of the foliation. Alvarez Lopez, Candel, and Moreira Galicia gave a version of a Molino-like theory for foliated spaces under the additional assumption that the closure of the holonomy pseudogroup is strongly quasi-analytic, that is, it satisfies the condition of local generation.
In this talk, we consider foliated spaces with totally disconnected transversals, which we call matchbox manifolds, and use the methods of topological dynamics and continuum theory to develop a Molino-like classification of all such spaces. We show that for matchbox manifolds, the Molino sequence need not be well-defined, and specify the conditions under which it is well-defined. We outline the classes of matchbox manifolds, for which the local generation condition holds or does not hold, and study other properties of these spaces. Inspired by the result of Lubotzky about the existence of torsion in profinite completions of torsion-free groups, we construct a class of examples with well-defined non-trivial Molino sequences, where the non-triviality of the Molino sequence cannot be explained by the holonomy properties of leaves in the matchbox manifold. The examples that we construct and study show that this class of dynamical systems is far from being completely classified.

Analysis and Applied Mathematics Seminar
Propagation of Long-Crested Water Waves, the Bore Case
Colette Guillopé (Université Paris-Est Créteil)
4:00 PM in SEO 636
TBA
Tuesday November 1, 2016
Logic Seminar
TBA
Alex Kruckman (IU Bloomington)
4:00 PM in SEO 427
Wednesday November 2, 2016
Statistics Seminar
Overlaps and Pathwise Localization in the Anderson Polymer Model
Mike Cranston (UCI)
4:00 PM in SEO 636
We consider large time behavior of typical paths under the Anderson polymer measure. If $P^x_\kappa$ is the measure induced by rate $\kappa,$ simple, symmetric random walk on $\mathbb{Z}^d$ started at $x,$ this measure is defined as $d\mu^x_{\kappa,\beta,T}T(X)={Z_{\kappa,\beta,T}}^{-1} \exp\left\{\beta\int_0^T dW_{X(s)}(s)\right\}dP^x_\kappa(X)$ where $\{W_x:x\in \mathbb{Z}^d\}$ is a field of $iid$ standard, one-dimensional Brownian motions, $\beta>0, \kappa>0$ and $Z_{\kappa,\beta,t}(x)$ the normalizing constant. We establish that the polymer measure gives a macroscopic mass to a small neighborhood of a typical path as $T \to \infty$, for parameter values outside the perturbative regime of the random walk, giving a pathwise approach to polymer localization, in contrast with existing results. The localization becomes complete as $\frac{\beta^2}{\kappa}\to\infty$ in the sense that the mass grows to 1. The proof makes use of the overlap between two independent samples drawn under the Gibbs measure $\mu^x_{\kappa,\beta,T}$, which can be estimated by the integration by parts formula for the Gaussian environment. Conditioning this measure on the number of jumps, we obtain a canonical measure which already shows scaling properties, thermodynamic limits, and decoupling of the parameters. This talk is based on joint work with Francis Comets.

Algebraic Geometry Seminar
TBA
Giulia Sacca (Stonybrook )
4:00 PM in SEO 427
Thursday November 3, 2016
Louise Hay Logic Seminar
TBA
Victoria Noquez (UIC)
4:00 PM in SEO 427
Friday November 4, 2016
Homotopy Theory Seminar
TBD
Tasos Moulinos (UIC)
12:30 PM in SEO 1227

Departmental Colloquium
Numerical Investigation of Crouzeix’s Conjecture
Michael Overton (Courant Institute, NYU)
3:00 PM in SEO 636
Crouzeix's conjecture is among the most intriguing developments in matrix theory in recent years. Made in 2004 by Michel Crouzeix, it postulates that, for any polynomial p and any matrix A, ||p(A)|| <= 2 max(|p(z)|: z in W(A)), where the norm is the 2-norm and W(A) is the field of values (numerical range) of A, that is the set of points attained by v*Av for some vector v of unit length. Remarkably, Crouzeix proved in 2007 that the inequality above holds if 2 is replaced by 11.08. Furthermore, it is known that the conjecture holds in a number of special cases, including n=2. We use nonsmooth optimization to investigate the conjecture numerically by attempting to minimize the “Crouzeix ratio”, defined as the quotient with numerator the right-hand side and denominator the left-hand side of the conjectured inequality. We present numerical results that lead to some theorems and further conjectures, including variational analysis of the Crouzeix ratio at conjectured global minimizers. All the computations strongly support the truth of Crouzeix’s conjecture.
This is joint work with Anne Greenbaum and Adrian Lewis.
Tea starts at 4:15 PM in 300 SEO
Monday November 7, 2016
Commutative Algebra Seminar
No Seminar -- Field Trip to UChicago's Geometric Langlands Seminar
N/A (N/A)
1:00 PM in SEO 427
Bhargav Bhatt will speak from 4:30-7:00 on Yves André's solution to the Direct Summand Conjecture at UChicago (see http://math.uchicago.edu/research/calendar/).

Analysis and Applied Mathematics Seminar
tba
Kui Ren (University of Texas at Austin)
4:00 PM in SEO 636
tba
Tuesday November 8, 2016
Logic Seminar
Strong Minimality and the Baldwin-Lachlan Characterization of Uncountable Categoricity in Continuous Logic
Victoria Noquez (UIC)
4:00 PM in SEO 427
Wednesday November 9, 2016
Algebraic Geometry Seminar
No Seminar
- (-)
4:00 PM in SEO 427

Statistics Seminar
TBA
Sanjib Basu (UIC)
4:00 PM in SEO 636
TBA
TBA
Friday November 11, 2016
Homotopy Theory Seminar
TBD
Maximilien Holmberg-Péroux (UIC)
12:30 PM in SEO 1227

Departmental Colloquium
TBA
Andrew Suk (UIC)
3:00 PM in SEO 636
Monday November 14, 2016
Commutative Algebra Seminar
TBA
Emily Witt (Kansas)
1:00 PM in SEO 427
TBA

Geometry, Topology and Dynamics Seminar
TBA
Yair Hartman (Northwestern University)
3:00 PM in SEO 636

Analysis and Applied Mathematics Seminar
TBA
Luis Silvestre (University of Chicago)
4:00 PM in SEO 636
Tuesday November 15, 2016
Logic Seminar
TBA
Garrett Ervin (UC Irvine)
4:00 PM in SEO 427
Wednesday November 16, 2016
Statistics Seminar
TBA
Si Tang (University of Chicago)
4:00 PM in SEO 636
TBA
TBA
Thursday November 17, 2016
Algebraic Geometry Seminar
TBA
Alena Pirutka (NYU)
4:00 PM in SEO 1227
Friday November 18, 2016
Homotopy Theory Seminar
TBD
Harry Smith (UIC)
12:30 PM in SEO 1227

Graduate day on Geometry and Topology
2 p.m. to 7:30 p.m.
2:00 PM in SEO 427
http://schapos.people.uic.edu/GT_2016.html
Monday November 21, 2016
Analysis and Applied Mathematics Seminar
TBA
Youngjoon Hong (UIC)
4:00 PM in SEO 636
TBA
Wednesday November 23, 2016
Algebraic Geometry Seminar
No Seminar
- (-)
4:00 PM in SEO 427
Monday November 28, 2016
Geometry, Topology and Dynamics Seminar
TBA
Lucas Branco (University of Oxford)
3:00 PM in SEO 636
TBA
Tuesday November 29, 2016
Logic Seminar
TBA
4:00 PM in SEO 427
Wednesday November 30, 2016
Algebraic Geometry Seminar
Pushforwards of pluricanonical bundles and morphisms to abelian varieties
Christian Schnell / David Yang (Stonybrook / MIT)
4:00 PM in SEO 427
In the past few years, people working on the analytic side of algebraic geometry have obtained two important new results: a version of the Ohsawa-Takegoshi extension theorem with sharp estimates (Blocki, Guan-Zhou), and the existence of canonical singular hermitian metrics on pushforwards of relative pluricanonical bundles (Berndtsson, Paun, Takayama, and others). In this talk, I will explore some consequences of this work for the study of morphisms to complex abelian varieties, including the recent proof of Iitaka's conjecture over abelian varieties (Cao-Paun). The talk will be understandable without any background in analysis.

Statistics Seminar
TBA
Ella Revzin (Precima)
4:00 PM in SEO 636
Thursday December 1, 2016
Louise Hay Logic Seminar
TBA
Hunter Chase (UIC)
4:00 PM in SEO 427
Friday December 2, 2016
Homotopy Theory Seminar
TBD
Joel Stapleton (UIC)
12:30 PM in SEO 1227

Departmental Colloquium
TBA
TBA (TBA)
3:00 PM in SEO 636
Monday December 5, 2016
Combinatorics Seminar
TBD
Radoslav Fulek (Institute of Science and Technology Austria)
2:00 PM in SEO 612
Monday January 23, 2017
Commutative Algebra Seminar
TBA
Axel Stabler (University of Michigan)
1:00 PM in SEO 427
TBA

Algebraic Geometry Seminar
TBA
Chenyang Xu (MIT / BICMR)
2:00 PM in SEO 427
TBA
Monday February 6, 2017
Geometry, Topology and Dynamics Seminar
TBA
Caglar Uyanik (UIUC)
3:00 PM in SEO 636
Monday March 6, 2017
Combinatorics Seminar
TBA
Tom Bohman (Carnegie Mellon University)
2:00 PM in SEO 612
Friday April 21, 2017
Departmental Colloquium
TBA
Sándor Kovács (University of Washington)
3:00 PM in SEO 636
TBA
Wednesday April 26, 2017
Algebraic Geometry Seminar
TBA
Tommaso de Fernex (University of Utah)
4:00 PM in SEO 427
TBA
Friday April 28, 2017
Departmental Colloquium
Height Zeta Functions
Yuri Tschinkel (NYU and Simons Foundation )
3:00 PM in TBA
Atkin Memorial Lecture
UIC LAS MSCS > seminars > seminar calendar