MSCS Seminar Calendar

Monday November 12, 2018
pdf * Mathematical Computer Science Seminar
Generalized Tur\'an problems for graphs and hypergraphs
Ruth Luo (UIUC)
3:00 PM in 427 SEO
We will talk about a generalization of the Tur\'an problem for hypergraphs: given a graph $F$, what is the maximum number of hyperedges an $r$-uniform $n$-vertex Berge $F$-free hypergraph can have? In particular, we will discuss tools used to reduce the hypergraph problem to problems for graphs. Finally, I will present some recent results for graphs without long Berge cycles. This is joint work with (different subsets of) Zoltan Furedi and Alexandr Kostochka.

pdf * Geometry, Topology and Dynamics Seminar
On Invariant Random Subgroups of Block-Diagonal Limits of Symmetric Groups
Constantine Medynets (U.S. Naval Academy)
3:00 PM in 636 SEO
We classify the ergodic invariant random subgroups of block-diagonal limits of symmetric groups in the cases when the groups are simple and the associated dimension groups have finite dimensional state spaces. These block-diagonal limits arise as the transformation groups (full groups) of Bratteli diagrams that preserve the cofinality of infinite paths in the diagram. Given a simple full group G admitting only a finite number of ergodic measures on the path-space X of the associated Bratteli diagram, we prove that every non-Dirac ergodic invariant random subgroup of G arises as the stabilizer distribution of the diagonal action on X^n for some n≥1. As a corollary, we establish that every group character χ of G has the form χ(g)=Prob(g∈K), where K is a conjugation-invariant random subgroup of G.

pdf * Analysis and Applied Mathematics Seminar
Multiscale/Multiphysics Coupling Framework for Bioprosthetic Heart Valve Damage
Yue Yu (Lehigh University)
4:00 PM in 636 SEO
Bioprosthetic heart valves (BHVs) are the most popular artificial replacements for diseased valves that mimic the structure of native valves. However, the life span of BHVs remains limited to 10-15 years, and the mechanisms that underlie BHVs failure remain poorly understood. Therefore, developing a unifying mathematical framework which captures material damage phenomena in the fluid-structure interaction environment would be extremely valuable for studying BHVs failure. Specifically, in this framework the computational domain is composed of three subregions: the fluid (blood) , the fracture structure (damaged BHVs) modeled by the recently developed nonlocal (peridynamics) theory, and the undamaged thin structure (undamaged BHVs). These three subregions are numerically coupled to each other with proper interface boundary conditions. In this talk, I will introduce two sub-problems and the corresponding numerical methods we have developed for this multiscale/multiphysics framework. In the first problem the coupling strategy for fluid and thin structure is investigated. This problem presents unique challenge due to the large deformation of BHV leaflets, which causes dramatic changes in the fluid subdomain geometry and difficulties on the traditional conforming coupling methods. To overcome the challenge, the immersogemetric method was developed where the fluid and thin structure are discretized separately and coupled through penalty forces. To ensure the capability of the developed method in modeling BHVs, we have verified and validated this method. In the second problem, we proposed a Neumann-type interface boundary condition for the nonlocal model. In the nonlocal models the Neumann-type boundary conditions should be defined in a nonlocal way, namely, on a region with non-zero volume outside the surface, while in fluid—structure interfaces the hydrodynamic loadings from the fluid side are typically provided on a sharp co-dimension one surface. Therefore, we have shown that our new nonlocal Neumann-type boundary condition provides an approximation of physical boundary conditions on a sharp surface, with an optimal asymptotic convergence rate to the local counter part. Based on this new boundary condition, we have developed a fluid—peridynamics coupling framework without overlapping regions.
Tuesday November 13, 2018
pdf * Graduate Groups and Dynamics Seminar
Balog-Szemeredi-Gowers Lemma
Sebastian Hurtado (University of Chicago)
3:00 PM in 1227 SEO

pdf * Logic Seminar
Functional transcendence results for automorphic functions
James Freitag (UIC)
3:30 PM in 427 SEO
We will discuss some recent new techniques to prove functional transcendence results for automorphic functions of discrete groups acting on the upper half plane.
Wednesday November 14, 2018
pdf * Mathematics Education Colloquium
Can Math Education Research Improve the Teaching of Abstract Algebra?
Aida Alibek (UIC)
12:00 PM in 612 SEO
Please join us for a discussion of the Fukawa-Connelly, Johnson & Keller paper from the Notices of AMS. No prior reading is required.
Everyone is welcome to join! Especially those involved in teaching Abstract Algebra for Undergraduate students!

pdf * Graduate Algebraic Geometry Seminar
Frobenius Splittings in Commutative Algebra
Ben Gould (UIC)
2:00 PM in 712 SEO

pdf * Algebraic K-Theory Seminar
String topology, noncommutative geometry, and integrable systems
Nick Rozenblyum (University of Chicago)
3:00 PM in 1227 SEO

pdf * Graduate Geometry, Topology and Dynamics Seminar
Hyperbolic Surfaces and Fuchsian Groups II
Nathan Lopez
4:00 PM in 612 SEO

pdf * Statistics Seminar
Factorizations and estimates of Dirichlet heat kernels for non-local operators with critical killings
Renming Song (UIUC)
4:00 PM in 636 SEO
In this talk I will discuss heat kernel estimates for critical perturbations of non-local operators. To be more precise, let $X$ be the reflected $\alpha$-stable process in the closure of a smooth open set $D$, and $X^D$ the process killed upon exiting $D$. We consider potentials of the form $\kappa(x)=C\delta_D(x)^{-\alpha}$ with positive $C$ and the corresponding Feynman-Kac semigroups. Such potentials do not belong to the Kato class. We obtain sharp two-sided estimates for the heat kernel of the perturbed semigroups. The interior estimates of the heat kernels have the usual $\alpha$-stable form, while the boundary decay is of the form $\delta_D(x)^p$ with non-negative $p\in [\alpha-1, \alpha)$ depending on the precise value of the constant $C$. Our result recovers the heat kernel estimates of both the censored and the killed stable process in $D$. Analogous estimates are obtained for the heat kernel of the Feynman-Kac semigroup of the $\alpha$-stable process in ${\mathbf R}^d\setminus \{0\}$ through the potential $C|x|^{-\alpha}$.
All estimates are derived from a more general result described as follows: Let $X$ be a Hunt process on a locally compact separable metric space in a strong duality with $\widehat{X}$. Assume that transition densities of $X$ and $\widehat{X}$ are comparable to the function $\widetilde{q}(t,x,y)$ defined in terms of the volume of balls and a certain scaling function. For an open set $D$ consider the killed process $X^D$, and a critical smooth measure on $D$ with the corresponding positive additive functional $(A_t)$. We show that the heat kernel of the the Feynman-Kac semigroup of $X^D$ through the multiplicative functional $\exp(-A_t)$ admits the factorization of the form ${\mathbf P}_x(\zeta >t)\widehat{\mathbf P}_y(\widehat{\zeta}>t)\widetilde{q}(t,x,y)$.
This is joint work with Soobin Cho, Panki Kim and Zoran Vondracek.

pdf * Algebraic Geometry Seminar
TBA
Mircea Mustata (University of Michigan)
4:00 PM in 427 SEO
Thursday November 15, 2018
pdf * Louise Hay Logic Seminar
Self-Verifying Axiom Systems
Will Adkisson (UIC)
4:00 PM in 427 SEO
Friday November 16, 2018
pdf * Departmental Colloquium
Applications of combinatorics
Bridget Tenner (DePaul)
3:00 PM in 636 SEO
We use enumerative and algebraic combinatorics to prove results on a range of topics. These include algebraic structures, tiling phenomena, pattern avoidance, and even applications to political science.
Monday November 19, 2018
pdf * Commutative Algebra Seminar
GKZ-systems and mixed Hodge modules
Uli Walther (Purdue University)
11:00 AM in 427 SEO
I will define GKZ-systems, and talk a little about their properties from the algebraic, analytic, and combinatorial point of view. Then I will discuss a theorem of Gelfand et al, and a sharpening by Mathias Schulze and myself, on the question which GKZ-systems arise as (D-module-)direct image of a natural D-module on a torus. In such cases, the GKZ-system can inherit a mixed Hodge module structure. I will then explain work with Thomas Reichelt that computes the weight filtration of this MHM structure on a class of GKZ-systems that comes up naturally in mirror symmetry. This complements work of Reichelt and Christian Sevenheck who computed the Hodge filtration, and supersedes computations of Batyrev who determined the weight filtration in a generic point. Very few of such explicitly computed structures seem to be known.

pdf * Geometry, Topology and Dynamics Seminar
Positivity in the asymptotic regime
Yanir Rubinstein (University of Maryland)
3:00 PM in 636 SEO
A general theme in geometry is the classification of algebraic/differential geometric structures which satisfy a positivity property. In this talk I will propose an ``asymptotic" version of this theme based on joint work with Cheltsov, Martinez-Garcia, and Zhang. On the algebraic side, we introduce the class of asymptotically log Fano varieties and state a classification theorem in dimension 2, generalizing the classical efforts of the Italian school. The novelty here is the use of tools of convex optimization. On the differential side, I will give a conjectural picture for existence of singular Kahler-Einstein , explain progress towards this conjecture, and, time permitting, relations to singular Kahler-Ricci solitons.

pdf * Analysis and Applied Mathematics Seminar
On a dissipative Gross-Pitaevskii-type model for exciton-polariton condensates
Ryan Obermeyer (University of Illinois at Chicago)
4:00 PM in 636 SEO
We study a generalized dissipative Gross-Pitaevskii-type model arising in the description of exciton-polariton condensates. We derive rigorous existence and uniqueness results for this model posed on the one dimensional torus and derive various a-priori bounds on its solution. Then, we analyze in detail the long time behavior of spatially homogenous solutions and their respective steady states. In addition, we will present numerical simulations in the case of more general initial data. We also study the corresponding adiabatic regime which results in a single damped-driven Gross-Pitaveskii equation and compare its dynamics to the one of the full coupled system.
Joint work with C. Sparber, P. Antonelli, P. Markowich, and J. Sierra

pdf * Graduate Combinatorics/MCS seminar
Analyzing Growth Rates of an Extremal Function for Hypergraphs
Sayan Mukherjee (UIC)
5:00 PM in 612 SEO
Tuesday November 20, 2018
pdf * Graduate Groups and Dynamics Seminar
Spectral gap for groups of algebraic matrices
Wouter van Limbeek (UIC)
3:00 PM in 1227 SEO
Previously we have established a spectral gap for weakly diophantine groups (first part of the work of Benoist-De Saxce). Today we'll cover the second part: We show that groups with algebraic entries are weakly diophantine.

pdf * Logic Seminar
An upper bound for uB-sealing
Grigor Sargsyan (Rutgers University)
3:30 PM in 427 SEO
Woodin showed that, assuming the existence of a supercompact cardinal and a class of Woodin cardinals, after collapsing a supercompact cardinal to be countable, the theory of L(Gamma_{uB}) is sealed. Here, Gamma_{uB} is the collection of the universally Baire sets of reals. We say that the theory of L(Gamma_{uB}) is sealed if for any V-generic g and a V[g]-generic h, there is an elementary embedding j: L(Gamma_uB)^{V[g]}-> L(Gamma_uB)^{V[g*h]}. It has been conjectured by the speaker that sealing has a weak large cardinal strength, and its weakness is the reason why the core model induction becomes so much more complicated after passing the threshold given by sealing. In a very recent work, the speaker and Trang showed that sealing is indeed weak, weaker than a Woodin cardinal that is itself a limit of Woodin cardinals. After stating the relevant theorems we will outline why exactly the core model induction becomes rather difficult after this threshold.
Monday November 26, 2018
pdf * Special Colloquium
Bernoulli shifts and entropy theory
Brandon Seward (Courant Institute )
3:00 PM in 636 SEO
In ergodic theory, one often studies measure-preserving actions of countable groups on probability spaces. Bernoulli shifts are a class of such actions that are particularly simple to define, but despite several decades of study some elementary questions about them still remain open, such as how they are classified up to isomorphism. Progress in understanding Bernoulli shifts has historically gone hand-in-hand with the development of a tool known as entropy. In this talk, I will review classical concepts and results, which apply in the case where the acting group is amenable, and then I will discuss recent developments that are beginning to illuminate the case of non-amenable groups.
There will be tea in SEO 300 starting at 4:15.

pdf * Analysis and Applied Mathematics Seminar
TBA
Ian Tice (Carnegie Mellon University)
4:00 PM in 636 SEO
Wednesday November 28, 2018
pdf * Geometry, Topology and Dynamics Seminar
TBA
Fedor Manin (Ohio State University)
3:00 PM in 636 SEO

pdf * Algebraic K-Theory Seminar
TBA
Joel Stapleton (UIC)
3:00 PM in 1227 SEO

pdf * Special Colloquium
TBA
Fedor Manin (Ohio State University)
3:00 PM in 636 SEO
TBA
There will be tea in SEO 300 starting at 4:15.

pdf * Statistics Seminar
TBA
Linyi Zhang (Milliman USA)
4:00 PM in 636 SEO
Friday November 30, 2018
pdf * Special Colloquium
TBA
Bena Tshishiku (Harvard)
3:00 PM in 636 SEO
TBA
There will be tea in SEO 300 starting at 4:15.
Monday December 3, 2018
pdf * Geometry, Topology and Dynamics Seminar
TBA
Wai Yeung Lam (Brown University)
3:00 PM in 636 SEO
TBA

pdf * Mathematical Computer Science Seminar
Algorithms for #BIS-hard problems on expander graphs
Matthew Jenssen (Oxford)
3:00 PM in 427 SEO
We give an FPTAS and an efficient sampling algorithm for the high-fugacity hard-core model on bounded-degree bipartite expander graphs and the low-temperature ferromagnetic Potts model on bounded-degree expander graphs. The results apply, for example, to random (bipartite) d-regular graphs, for which no efficient algorithms were known for these problems (with the exception of the Ising model) in the non-uniqueness regime of the infinite d-regular tree. Joint work with Peter Keevash and Will Perkins.

pdf * Analysis and Applied Mathematics Seminar
Interfacial dynamics of dissolving objects in fluid flow
Christopher Rycroft (Harvard University)
4:00 PM in 636 SEO
An advection–diffusion-limited dissolution model of an object being eroded by a two-dimensional potential flow will be presented. By taking advantage of conformal invariance of the model, a numerical method will be introduced that tracks the evolution of the object boundary in terms of a time-dependent Laurent series. Simulations of several dissolving objects will be shown, all of which show collapse to a single point in finite time. The simulations reveal a surprising connection between the position of the collapse point and the initial Laurent coefficients, which was subsequently derived analytically.
Wednesday December 5, 2018
pdf * Algebraic K-Theory Seminar
Stratifications and sheaves on the Ran space
Jānis Lazovskis (UIC)
3:00 PM in 1227 SEO

pdf * Mathematical Computing Laboratory
Fall 2018 MCL Research Expo

3:30 PM in 709 SEO

pdf * Statistics Seminar
TBA
Viswanath Devanarayan (UIC)
4:00 PM in 636 SEO
Friday December 7, 2018
pdf * Departmental Colloquium
TBA
Arend Bayer (Edinburgh)
3:00 PM in 636 SEO
Tuesday January 15, 2019
pdf * Logic Seminar
TBA
Sam Corson (University of the Basque Country)
3:30 PM in 427 SEO
Wednesday January 23, 2019
pdf * Statistics Seminar
TBA
Wenhui Sheng (Marquette University)
4:00 PM in 636 SEO
Monday January 28, 2019
pdf * Geometry, Topology and Dynamics Seminar
TBA
Kevin Schreve (University of Chicago)
3:00 PM in 636 SEO

pdf * Analysis and Applied Mathematics Seminar
TBA
Yannis Giannoulis (University of Ioannina, Greece)
4:00 PM in 636 SEO
Monday February 11, 2019
pdf * Analysis and Applied Mathematics Seminar
TBA
Shawn Walker (Louisiana State University)
4:00 PM in 636 SEO
Wednesday February 13, 2019
pdf * Statistics Seminar
TBA
Chuanshu Ji (University of North Carolina at Chapel Hill)
4:00 PM in 636 SEO
Wednesday February 20, 2019
pdf * Statistics Seminar
TBA
Subhashis Ghoshal (North Carolina State University)
4:00 PM in 636 SEO
Friday March 1, 2019
pdf * Departmental Colloquium
Part of UIC Distinguished Lecture Series
Peter Sarnak (Princeton)
3:00 PM in 636 SEO
Monday March 4, 2019
pdf * Analysis and Applied Mathematics Seminar
TBA
Gideon Simpson (Drexel University)
4:00 PM in 636 SEO
Wednesday March 6, 2019
pdf * Statistics Seminar
TBA
Yue Niu (University of Arizona)
4:00 PM in 636 SEO
Friday March 8, 2019
pdf * Departmental Colloquium
TBA
Bhargav Narayanan (Rutgers)
3:00 PM in 636 SEO
Monday March 11, 2019
pdf * Analysis and Applied Mathematics Seminar
TBA
Paula Vasquez (University of South Carolina)
4:00 PM in 636 SEO
Wednesday March 13, 2019
pdf * Statistics Seminar
TBA
Dr. Xiao Zhang (Michigan Technological University)
4:00 PM in 636 SEO
TBA
Friday March 15, 2019
pdf * Departmental Colloquium
TBA
Kathryn Mann (Brown University)
3:00 PM in 636 SEO
Monday March 18, 2019
pdf * Analysis and Applied Mathematics Seminar
TBA
Ying Wang (University of Oklahoma)
4:00 PM in 636 SEO
Wednesday March 20, 2019
pdf * Statistics Seminar
TBA
Mengjia Yu (UIUC)
4:00 PM in 636 SEO
Wednesday March 27, 2019
pdf * Statistics Seminar
TBA
Xianyang Zhang (Texas A&M University)
4:00 PM in 636 SEO
Wednesday April 3, 2019
pdf * Statistics Seminar
TBA
Marco Ferreira (Virginia Tech)
4:00 PM in 636 SEO
Wednesday April 10, 2019
pdf * Statistics Seminar
TBA
William Li (Shanghai Advanced Institute of Finance)
4:00 PM in 636 SEO
Friday April 12, 2019
pdf * Departmental Colloquium
TBD
Nikhil Srivastava (UC Berkeley)
3:00 PM in 636 SEO
Wednesday April 17, 2019
pdf * Statistics Seminar
TBA
Yehua Li (University of California at Riverside)
4:00 PM in 636 SEO
Monday April 22, 2019
pdf * Mathematical Computer Science Seminar
TBA
Andrew Suk (UCSD)
3:00 PM in 427 SEO
Wednesday April 24, 2019
pdf * Statistics Seminar
TBA
Leonard Stefanski (North Carolina State University)
4:00 PM in 636 SEO
Wednesday May 8, 2019
pdf * Statistics Seminar
TBA
Xiaotong Shen (University of Minnesota)
4:00 PM in 636 SEO
Friday November 1, 2019
pdf * Departmental Colloquium
Midwest Dynamical Systems Conference
TBA (TBA)
3:00 PM in 636 SEO
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