Talk_id  Date  Speaker  Title 
29376

Tuesday 9/6 11:00 AM

Lucas Hall, MSU

Skew Products: Coactions You Can See
 Lucas Hall, MSU
 Skew Products: Coactions You Can See
 09/06/2022
 11:00 AM  11:50 AM
 C304 Wells Hall
 Brent Nelson (banelson@msu.edu)
The speaker introduces topological quivers and constructs their associated C*algebra. We present two independent constructions which arise in the presence of a cocycle (the topological ”skew product" and the algebraic coaction) and show that the constructions agree in a suitable sense. Along the way, we characterize the skew product based on some associated topological dynamics. Time permitting, we will explore future directions.

29397

Tuesday 9/6 3:00 PM

G&T Seminar, MSU

Organizational Meeting
 G&T Seminar, MSU
 Organizational Meeting
 09/06/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Vijay B Higgins (higgi231@msu.edu)
Organizational meeting for the GT seminar this Fall.

29378

Wednesday 9/7 4:10 PM

Sasha Volberg, MSU

Heat smoothing conjecture and BernsteinMarkov inequalities on Hamming cube
 Sasha Volberg, MSU
 Heat smoothing conjecture and BernsteinMarkov inequalities on Hamming cube
 09/07/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
Hamming cube and its various Poincaré type inequalities represent a crucial model for many questions ranging from Banach space theory to graph theory to theoretical computer science. We present some estimates for tail spaces on Hamming cube. We use the analytic paraproduct operator for that. We also show some BernsteinMarkov inequalities, here the novelty is in getting rid of some irritating logarithms.

29391

Thursday 9/8 3:00 PM

Lara Pudwell, Valparaiso University

Patternavoiding parking functions
 Lara Pudwell, Valparaiso University
 Patternavoiding parking functions
 09/08/2022
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
We extend the classical definition of patterns in permutations to parking functions. In particular we study parking functions that avoid permutations of length 3. A number of wellknown combinatorial sequences arise in our analysis, and this talk will highlight several bijective results. This project is joint work with Ayomikun Adeniran.

29383

Thursday 9/8 4:10 PM

Leonid Parnovski, University College London

Floating mats and sloping beaches: spectral asymptotics of the Steklov problem on polygons
 Leonid Parnovski, University College London
 Floating mats and sloping beaches: spectral asymptotics of the Steklov problem on polygons
 09/08/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
I will discuss asymptotic behaviour of the eigenvalues of the Steklov problem (aka DirichlettoNeumann operator) on curvilinear polygons. The answer is completely unexpected and depends on the arithmetic properties of the angles of the polygon.

29409

Monday 9/12 12:30 PM

Leonid Chekhov, Michigan State University

Symplectic groupoid and cluster algebra description of closed Riemann surfaces
 Leonid Chekhov, Michigan State University
 Symplectic groupoid and cluster algebra description of closed Riemann surfaces
 09/12/2022
 12:30 PM  1:30 PM
 C304 Wells Hall
 Linhui Shen (shenlin1@msu.edu)
We use the FockGoncharov higher Teichmuller space directed networks to solve the symplectic groupoid condition: parameterize pairs of $SL_n$ matrices (B,A) with A unipotent such that $BAB^T$ is also unipotent. A natural LiePoisson bracket on B generates the Goldman bracket on elements of A and $BAB^T$, which are simultaneously elements of the corresponding upper cluster algebras. Using this input we identify the space of Xcluster algebra elements with Teichmuller spaces of closed Riemann surfaces of genus 2 (for $n$=3) and 3 (for $n$=4) endowed with Goldman bracket structure: for $g$=2 all geodesic functions are positive Laurent polynomials and Dehn twists correspond to mutations in the corresponding quivers. This is the work in progress with Misha Shapiro.

29401

Monday 9/12 4:00 PM

Brent Nelson, MSU

Making Weight
 Brent Nelson, MSU
 Making Weight
 09/12/2022
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
A weight on a von Neumann algebra is a positive linear map that is permitted to be infinitely valued. It is a generalization of a positive linear functional that arises naturally in the context of crossed products by nondiscrete groups, and they are vital to the study of purely infinite von Neumann algebras. In this talk I will provide an introduction to the theory of weights that assumes only the definition of a von Neumann algebra.

29377

Tuesday 9/13 11:00 AM

Lara Ismert, Embry–Riddle Aeronautical University

A Liouvilleesque theorem for a weaklydefined derivation on B(H)
 Lara Ismert, Embry–Riddle Aeronautical University
 A Liouvilleesque theorem for a weaklydefined derivation on B(H)
 09/13/2022
 11:00 AM  11:50 AM
 C304 Wells Hall
 Brent Nelson (banelson@msu.edu)
Liouville’s Theorem states that any bounded entire function on the complex plane is necessarily constant. In this talk, we discuss an analogous theorem for a weaklydefined derivation on B(H) studied in recent years by Erik Christensen. As a consequence, we provide new sufficient conditions for when two operators which satisfy the Heisenberg Commutation Relation must both be unbounded.

29410

Wednesday 9/14 3:00 PM

Brendon Rhoades, UCSD

Superspace, Vandermondes, and representations
 Brendon Rhoades, UCSD
 Superspace, Vandermondes, and representations
 09/14/2022
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
We present an extension of the Vandermonde determinant from the polynomial ring to superspace. These superspace Vandermondes are used to construct modules over the symmetric group with (occasionally conjectural) connections to geometry and coinvariant theory. Joint with Andy Wilson.

29412

Thursday 9/15 3:00 PM

Jie Yang, MSU

Organizing meeting for Student Number Theory Seminar
 Jie Yang, MSU
 Organizing meeting for Student Number Theory Seminar
 09/15/2022
 3:00 PM  4:00 PM
 C204A Wells Hall
 Jie Yang (yangji79@msu.edu)
In this first meeting, I'll give some motivations towards the study of padic modular forms, and explain some central concepts in "eigenvarieties machine" introduced by K. Buzzard. In the end, we will discuss the plan for this seminar.

29402

Thursday 9/15 4:10 PM

Jenny Wilson, University of Michigan

Stability patterns in configuration spaces
 Jenny Wilson, University of Michigan
 Stability patterns in configuration spaces
 09/15/2022
 4:10 PM  5:00 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Olga Turanova (turanova@msu.edu)
This talk will give an introduction of the recent field of 'representation stability'. I will discuss how we can use representation theory to illuminate the structure of certain families of groups or topological spaces with actions of the symmetric groups, focusing on configuration spaces as an illustrative example.

29415

Friday 9/16 4:00 PM

Anna Veselovska, Department of Mathematics, Technical University of Munich, Germany

SuperResolution on the TwoDimensional Unit Sphere
 Anna Veselovska, Department of Mathematics, Technical University of Munich, Germany
 SuperResolution on the TwoDimensional Unit Sphere
 09/16/2022
 4:00 PM  5:00 PM
 C304 Wells Hall
 Mark A Iwen (iwenmark@msu.edu)
In this talk, we discuss the problem of recovering an atomic measure on the unit 2sphere S^2 given finitely many moments with respect to spherical harmonics. The analysis relies on the formulation of this problem as an optimization problem on the space of bounded Borel measures on S^2 as suggested by Y. de
Castro & F. Gamboa and E. Candes & C. FernandezGranda. We construct a dual certificate using a kernel given in an explicit form and make a concrete analysis of the interpolation problem. We support our theoretical results by various numerical examples related to direct solution of the optimization
problem and its discretization.
This is a joint work with Frank Filbir and Kristof Schroder.

29414

Monday 9/19 12:30 PM

Alexander Vainshtein, Haifa University

Cluster structures on SL_n and the BelavinDrinfeld classification
 Alexander Vainshtein, Haifa University
 Cluster structures on SL_n and the BelavinDrinfeld classification
 09/19/2022
 12:30 PM  1:30 PM
 C304 Wells Hall
 Michael Shapiro (mshapiro@msu.edu)
Cluster structures were discovered by S. Fomin and A. Zelevinsky about twenty years
ago and quickly found applications in various fields of mathematics and mathematical physics.
In the latter, several advances were made in a study of classical and quantum integrable
systems arising in the context of cluster structures. These systems "live" on PoissonLie
groups and their Poisson homogeneous spaces, hence it is important to understand an
interplay between cluster and Poisson structures on such objects.
In this talk I will explain a construction of a family of (generalized) cluster structures in the
algebra of regular functions on SL_n related to the BelavinDrinfeld classification
of PoissonLie structures on SL_n.
Based on a joint work with M.~Gekhtman (Notre Dame) and M.~Shapiro (MSU).

29413

Monday 9/19 1:00 PM

Craig Gross, MSU

All aboard! A mathematical study of transit equity in Baltimore
 Craig Gross, MSU
 All aboard! A mathematical study of transit equity in Baltimore
 09/19/2022
 1:00 PM  2:00 PM
 C117 Wells Hall
(Virtual Meeting Link)
 Craig Gross (grosscra@msu.edu)
In 2015, the governor of Maryland canceled a light rail project through the city of Baltimore that had been planned and funded for over a decade. Instead, the money was diverted to funding highways near the richer, whiter suburbs of the city. As Baltimore is home to some of the most extreme classdisparity and segregation in the country, this decision significantly hurt the potential for a more equitable transit system. But by how much?
$\\$
This talk will be a tour through a mathematical investigation of how the canceled light rail might have increased access to jobs across the city. In particular, we use some dimensionreduction and clustering algorithms on CDC Social Vulnerability Indices to explore which parts of the city may be socioeconomically disadvantaged. We then compute job accessibility metrics to determine how the light rail would have affected these regions. We also give some considerations for converting a collection of many relevant indicators into more interpretable, manageable metrics for future transit studies.
$\\$
This is joint work with Adam Lee, Kethaki Varadan, and Yangxinyu Xie.
$\\$
This will be a hybrid seminar and take place in C117 Wells Hall and via Zoom at https://msu.zoom.us/j/99426648081?pwd=ZEljM3BPUXg2MjVUMVM5TnlzK2NQZz09 .

29424

Monday 9/19 4:00 PM

Brent Nelson, MSU

Worth Their Weight
 Brent Nelson, MSU
 Worth Their Weight
 09/19/2022
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
I will continue my introduction to weights. I will briefly mention equivalent conditions of normality for weights before moving onto a discussion of semicyclic representations and TomitaTakesaki theory. I will conclude with a detailed examination of Plancherel weights on locally compact groups.

29419

Tuesday 9/20 11:00 AM

Alberto Takase, MSU and UC Irvine

Spectral estimates of dynamicallydefined and amenable operator families (In collaboration with Siegfried Beckus)
 Alberto Takase, MSU and UC Irvine
 Spectral estimates of dynamicallydefined and amenable operator families (In collaboration with Siegfried Beckus)
 09/20/2022
 11:00 AM  11:50 AM
 C304 Wells Hall
 Ilya Kachkovskiy (ikachkov@msu.edu)
For dynamicallydefined operator families, the Hausdorff distance of the spectra is estimated by the distance of the underlying dynamical systems while the group is amenable.
We prove that if the group has strict polynomial growth and both the group action and the coefficients are Lipschitz continuous, then the spectral estimate has a square root behavior or, equivalently, the spectrum map is $\frac{1}{2}$Holder continuous.
We prove the behavior can be improved resulting in the spectrum map being Lipschitz continuous if the coefficients are locallyconstant.
In 1990, the square root behavior was established for the Almost Mathieu Operator or, more generally, the quasiperiodic operators with Lipschitz continuous potentials.
Our results extend the square root behavior to a bigger class of operators such as (magnetic) discrete Schrodinger operators with finite range and with Lipschitz continuous coefficients.

29403

Tuesday 9/20 3:00 PM

Bin Sun, Oxford

$L^2$Betti numbers of fiber bundles
 Bin Sun, Oxford
 $L^2$Betti numbers of fiber bundles
 09/20/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Vijay B Higgins (higgi231@msu.edu)
We study the $L^2$Betti numbers of fiber bundles $F \rightarrow E \rightarrow B$ of manifolds. Under certain conditions (e.g., when $F$ is simply connected), $b_*^{(2)}(E)$ can be computed using the twisted $L^2$Betti numbers of $B.$ We relate the twisted and untwisted $L^2$Betti numbers of $B$ when $\pi_1(B)$ is locally indicable. As an application, we compute $b_*^{(2)}(E)$ when $B$ is either a surface or a nonpositively curved $3$manifold. This is a joint work with Dawid Kielak.

29425

Tuesday 9/20 4:00 PM


Organizational Meeting

 Organizational Meeting
 09/20/2022
 4:00 PM  5:00 PM
 C517 Wells Hall
 Ivan So (soivan@msu.edu)
No abstract available.

29416

Wednesday 9/21 3:00 PM

Alex Wilson, Dartmouth

A DiagramLike Basis for the Multiset Partition Algebra
 Alex Wilson, Dartmouth
 A DiagramLike Basis for the Multiset Partition Algebra
 09/21/2022
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
There's a classical connection between the representation theory of the symmetric group and the general linear group called SchurWeyl Duality. Variations on this principle yield analogous connections between the symmetric group and other objects such as the partition algebra and more recently the multiset partition algebra. The partition algebra has a wellknown basis indexed by graphtheoretic diagrams which allows the multiplication in the algebra to be understood visually as combinations of these diagrams. I will present an analogous basis for the multiset partition algebra and show how this basis can be used to describe generators and construct representations for the algebra.

29380

Wednesday 9/21 4:10 PM

Michael McNulty, MSU

Conditionally Stable SelfSimilar Blowup for the Supercritical Quadratic Wave Equation Beyond the Light Cone
 Michael McNulty, MSU
 Conditionally Stable SelfSimilar Blowup for the Supercritical Quadratic Wave Equation Beyond the Light Cone
 09/21/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
Nonlinear wave equations of powertype serve as excellent toy models for geometric PDEs such as the YangMills and wave maps equations. Of great interest in the energy supercritical setting is that of threshold phenomena. In this setting, unstable selfsimilar blowup solutions are believed to play an essential role in describing the threshold of singularity formation. We will discuss the stability of an explicitly known, unstable selfsimilar blowup solution of the energy supercritical quadratic wave equation in a region of spacetime which extends beyond the time of blowup. To overcome this instability, we introduce a new canonical method to investigate unstable selfsimilar solutions. This work represents the first steps toward an understanding of threshold phenomena in the energy supercritical setting.

29438

Thursday 9/22 2:30 PM

Rayan Saab, University of California, San Diego (UCSD)

Quantizing neural networks
 Rayan Saab, University of California, San Diego (UCSD)
 Quantizing neural networks
 09/22/2022
 2:30 PM  3:30 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Mark A Iwen (iwenmark@msu.edu)
Neural networks are highly nonlinear functions often parametrized by a staggering number of weights. Miniaturizing these networks and implementing them in hardware is a direction of research that is fueled by a practical need, and at the same time connects to interesting mathematical problems. For example, by quantizing, or replacing the weights of a neural network with quantized (e.g., binary) counterparts, massive savings in cost, computation time, memory, and power consumption can be attained. Of course, one wishes to attain these savings while preserving the action of the function on domains of interest.
We present datadriven and computationally efficient methods for quantizing the weights of already trained neural networks and we prove that our methods have favorable error guarantees under a variety of assumptions. We also discuss extensions and provide the results of numerical experiments, on large multilayer networks, to illustrate the performance of our methods. Time permitting, we will also discuss open problems and related areas of research.

29423

Thursday 9/22 3:00 PM

Peikai Qi, MSU

Modular form and Hecke operator1
 Peikai Qi, MSU
 Modular form and Hecke operator1
 09/22/2022
 3:00 PM  4:00 PM
 C204A Wells Hall
 Peikai Qi (qipeikai@msu.edu)
In the talk, we will review the definition of modular form and hecke algebra.

29387

Thursday 9/22 4:10 PM

Chenyang Xu, Princeton University

Kstability and birational geometry
 Chenyang Xu, Princeton University
 Kstability and birational geometry
 09/22/2022
 4:10 PM  5:00 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Joseph Waldron (waldro51@msu.edu)
The notion of Kstability for a Fano varieties was introduced by differential geometers in late 90s, to capture the existence of a KählerEinstein metric. In the last decade, it has gradually become clear to algebraic geometers that Kstability provides a rich algebraic theory in higher dimensional geometry. In particular, it can be used to solve the longstanding question of constructing moduli spaces for Fano varieties.
I will survey the background of Kstability and how algebraic geometers’ understanding of it has evolved. In particular, I will explain algebraic geometry plays a key role of establishing the equivalence between Kstability and the existence of a KählerEinstein metric, i.e. the YauTianDonaldson Conjecture, for all Fano varieties. If time permits, I want to also discuss the construction of Kmoduli spaces parametrizing Fano varieties, and how the recipe given by Kstability can be used to resolve the issues that mystify people for a long time.

29421

Monday 9/26 12:30 PM

Jiuzu Hong, University of North Carolina at Chapel Hill

BD Schubert varieties of parahoric group schemes and global Demazure modules of twisted current algebras
 Jiuzu Hong, University of North Carolina at Chapel Hill
 BD Schubert varieties of parahoric group schemes and global Demazure modules of twisted current algebras
 09/26/2022
 12:30 PM  1:30 PM
 C304 Wells Hall
 Linhui Shen (shenlin1@msu.edu)
It is wellknown that there is a duality between affine Demazure modules and the spaces of sections of line bundles on Schubert varieties in affine Grassmannians. This should be regarded as a local theory. In this talk, I will explain an algebraic theory of global Demazure modules of twisted current algebras. Moreover, these modules are dual to the spaces of sections of line bundles on BeilinsonDrinfeld Schubert varieties of certain parahoric groups schemes, where the factorizations of global Demazure modules are compatible with the factorizations of line bundles. This generalizes the work of DumanskiFeiginFinkelberg in the untwisted setting. In order to establish this duality in the twisted case, following the works of Zhu, we prove the flatness of BD Schubert varieties, and establish factorizable and equivariant structures on the rigidified line bundles over BD Grassmannians of these parahoric group schemes. This work is joint with Huanhuan Yu.

29427

Monday 9/26 1:00 PM

Remy Liu, MSU

Understanding dataset characteristics via diffusion on graph
 Remy Liu, MSU
 Understanding dataset characteristics via diffusion on graph
 09/26/2022
 1:00 PM  2:00 PM
 C117 Wells Hall
(Virtual Meeting Link)
 Craig Gross (grosscra@msu.edu)
Classical graph signal processing provides powerful techniques for understanding and modifying graph signals from the spectral domain, but they come with high computational costs. More recently, diffusion on graphs has been sought as an alternative approach to modifying graph signals; it is much more computationally efficient and is easy to interpret from the spatial perspective. Here, we present two different studies utilizing diffusion wavelets on a graph to filter graph signals for downstream analysis. In the first study, we aim to understand how and what is being utilized by Graph Neural Networks to achieve graphrelated tasks. We do so by observing the performance difference between using the filtered graph and the original graph. We demonstrate that some image datasets, such as CIFAR and MNIST, rely on lowfrequency signals; on the contrary, heterophilic datasets, such as WebKB, rely more heavily on highfrequency signals. In the second study on computational biology using gene interaction networks and gene expression data, we observe similar results where different frequency bands perform differently in a taskspecific manner. In summary, our studies demonstrate the practical usage of graph diffusion to modify graph signals, leading to improved downstream prediction performance and a better understanding of the graph datasets' characteristics.
$\\$
This will be a hybrid seminar and take place in C117 Wells Hall and via Zoom at https://msu.zoom.us/j/99426648081?pwd=ZEljM3BPUXg2MjVUMVM5TnlzK2NQZz09 .

29417

Monday 9/26 3:00 PM

Patrick Daniels, University of Michigan

Canonical integral models for Shimura varieties defined by tori
 Patrick Daniels, University of Michigan
 Canonical integral models for Shimura varieties defined by tori
 09/26/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Georgios Pappas (pappasg@msu.edu)
Pappas and Rapoport have recently conjectured the existence of canonical integral models for Shimura varieties with parahoric level structure, which are characterized using Scholze's theory of padic shtukas. We will illustrate the conjecture using the example of Shimura varieties defined by tori, where (surprisingly) the theory is already nontrivial. Along the way we will explain a connection with the BhattScholze theory of prismatic Fcrystals.

29408

Monday 9/26 4:00 PM

Aldo Garcia Guinto, MSU

Conjugate Variables and Dual Systems
 Aldo Garcia Guinto, MSU
 Conjugate Variables and Dual Systems
 09/26/2022
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
In free probability, the semicircular operators are the analogue of the Gaussian distribution in classical probability. We will be using the semicircular operators to motivate two notions of free probability: conjugate variables and dual systems. The conjugate variables are used to define free Fisher information, which is analogue of Fisher information in classical probability. While the dual systems are related to a cohomology theory for von Neumann algebras. It turns out that these two notions are not as different as they may seem.

29429

Wednesday 9/28 3:00 PM

Ayomikun Adeniran, Colby College

Parking completions
 Ayomikun Adeniran, Colby College
 Parking completions
 09/28/2022
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
Parking functions are wellknown objects in combinatorics. One interesting generalization of parking functions are parking completions. A parking completion corresponds to a set of preferences where all cars park assuming some of the spots on the street are already occupied. In this talk, we will explore how parking completions are related to restricted lattice paths. We will also present results for both the ordered and unordered variations of the problem by use of a pair of operations (termed Join and Split). A nice consequence of our results is a new volume formula for most PitmanStanley polytopes. This is joint work with H. Nam, P.E. Harris, G. DorpalenBarry, S. Butler, J.L. Martin, C. Hettle, and Q. Liang.

29389

Wednesday 9/28 4:10 PM

ShiZhuo Looi, UC Berkeley

Asymptotics for odd and evendimensional waves
 ShiZhuo Looi, UC Berkeley
 Asymptotics for odd and evendimensional waves
 09/28/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
In this talk, I will give a survey of recent and upcoming results on various linear, semilinear and quasilinear wave equations on a wide class of dynamical spacetimes in various even and odd spatial dimensions. These results include asymptotics for a wide range of nonlinearities. We also highlight a dichotomy in odd dimensions between stationary and nonstationary backgrounds and explain how the stationary backgrounds lead to a faster decay rate for waves.
For many of these results, the spacetimes under consideration have only weak asymptotic flatness conditions and are allowed to be large perturbations of the Minkowski spacetime. We explain the dichotomy between even and odddimensional wave behaviour and how we view this dichotomy as a generalisation of the contrast between the classical weak Huygens' principle and the classical strong Huygens' principle. Part of this work is joint with Mihai Tohaneanu and Jared Wunsch.

29442

Thursday 9/29 3:00 PM

Peikai Qi, MSU

Hecke algebra and AtkinLehnerLi’s theory
 Peikai Qi, MSU
 Hecke algebra and AtkinLehnerLi’s theory
 09/29/2022
 3:00 PM  4:00 PM
 C204A Wells Hall
 Peikai Qi (qipeikai@msu.edu)
We will use double closet to define Hecke algebra. And then we will have an review of AtkinLehnerLi’s theory without proof. If you miss the last seminar, it doesn’t matter. you can also understand most of this section.

29393

Thursday 9/29 4:10 PM

Nam Le, Indiana University Bloomington

Hessian eigenvalues and hyperbolic polynomials
 Nam Le, Indiana University Bloomington
 Hessian eigenvalues and hyperbolic polynomials
 09/29/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
Hessian eigenvalues are natural nonlinear analogues of the classical Dirichlet eigenvalues. The Hessian eigenvalues and their corresponding eigenfunctions are expected to share many analytic and geometric properties (such as uniqueness, stability, maxmin principle, global smoothness, BrunnMinkowski inequality, etc) as their Dirichlet counterparts. In this talk, I will discuss these issues and some recent progresses in various geometric settings. The focus will be mostly on the case of the MongeAmpere eigenfunctions and related degenerate equations. I will also explain the unexpected role of hyperbolic polynomials in our analysis. I will not assume any familiarity with these concepts.

29439

Monday 10/3 4:00 PM

Lucas Hall, MSU

Introduction to Graph Algebras
 Lucas Hall, MSU
 Introduction to Graph Algebras
 10/03/2022
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
We introduce directed graphs and demonstrate how to generate a C*algebra which reflects certain features of the graph. Time permitting, we will introduce two uniqueness theorems for their representations and explore a few of their consequences.

29407

Tuesday 10/4 11:00 AM

Bin Sun, University of Oxford

Generalized wreath products and rigidity of their von Neumann algebras
 Bin Sun, University of Oxford
 Generalized wreath products and rigidity of their von Neumann algebras
 10/04/2022
 11:00 AM  11:50 AM
 C304 Wells Hall
 Brent Nelson (banelson@msu.edu)
We construct the first positive examples to the Connes' Rigidity Conjecture, i.e., we construct groups $G$ with Kazhdan's property (T) such that if $H$ is a group with the same von Neumann algebra as $G$, then $H\cong G$. In this talk, I will focus on the grouptheoretic side of this result and talk about how we applied geometric group theory to solve problems from von Neumann algebra. This is joint work with Ionut Chifan, Adrian Ioana, and Denis Osin.

30445

Tuesday 10/4 1:00 PM

Round Table Discussion, MSU

Assessment Modalities in gateway courses
 Round Table Discussion, MSU
 Assessment Modalities in gateway courses
 10/04/2022
 1:00 PM  2:00 PM
 C517 Wells Hall
 Tsvetanka Sendova (tsendova@msu.edu)
No abstract available.

30447

Tuesday 10/4 3:00 PM

Peter Johnson, Michigan State University

Knot lattice homology and the GukovManolescu 2variable series
 Peter Johnson, Michigan State University
 Knot lattice homology and the GukovManolescu 2variable series
 10/04/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Peter Kilgore Johnson (john8251@msu.edu)
In previous work of Akhmechet, Krushkal, and the speaker, a unification of lattice cohomology and the $\widehat{Z}$invariant was established. Both theories are combinatorially defined invariants of plumbed 3manifolds, but with quite different origins. Lattice cohomology, due to Némethi, is motivated by the study of normal surface singularities and is isomorphic to Heegaard Floer homology for plumbing trees. On the other hand, $\widehat{Z}$, due to GukovPeiPutrovVafa, is a power series coming from a physical theory and is conjectured to recover quantum invariants of 3manifolds at roots of unity. In this talk, I will discuss work in progress relating knot lattice homology and the GukovManolescu 2variable series, the knot theoretic counterparts to lattice homology and $\widehat{Z}$. This is joint work with Ross Akhmechet and Sunghyuk Park.

30454

Tuesday 10/4 4:30 PM

Ivan So

Basics on Intersection Theory
 Ivan So
 Basics on Intersection Theory
 10/04/2022
 4:30 PM  5:30 PM
 C517 Wells Hall
 Ivan So ()
No abstract available.

29446

Wednesday 10/5 3:00 PM

Caroline Klivans, Brown University

Flowfiring processes
 Caroline Klivans, Brown University
 Flowfiring processes
 10/05/2022
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
I will discuss a discrete nondeterministic flowfiring process for topological cell complexes. The process is a form of discrete diffusion; a flow is repeatedly diverted according to a discrete Laplacian. The process is also an instance of higherdimensional chipfiring. I will motivate and introduce the system and then focus on two important features – whether or not the system is terminating and whether or not the system is confluent.

29392

Wednesday 10/5 4:10 PM

Konstantin Matetski, MSU

Polynuclear growth and the Toda lattice
 Konstantin Matetski, MSU
 Polynuclear growth and the Toda lattice
 10/05/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
Polynuclear growth is one of the basic models in the KardarParisiZhang universality class, which describes a onedimensional crystal growth. For a particular initial state, it describes the length of the longest increasing subsequence for uniformly random permutations (the problem first studied by S. Ulam). In my joint work with J. Quastel and D. Remenik we expressed the distribution functions of the polynuclear growth in terms of the solutions of the Toda lattice, one of the classical integrable systems. A suitable rescaling of the model yields a nontrivial continuous limit of the polynuclear growth (the KPZ fixed point) and the respective equations (KadomtsevPetviashvili).

29435

Thursday 10/6 2:30 PM

Weijie Su, University of Pennsylvania

1WMINDS talk (passcode is the first prime number > 100).
 Weijie Su, University of Pennsylvania
 1WMINDS talk (passcode is the first prime number > 100).
 10/06/2022
 2:30 PM  3:30 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Mark A Iwen (iwenmark@msu.edu)
See https://sites.google.com/view/mindsseminar/home

29263

Thursday 10/6 4:10 PM

Lisa Piccirillo, Massachusetts Institute of Technology

Exotic phenomena in 4dimensional topology
 Lisa Piccirillo, Massachusetts Institute of Technology
 Exotic phenomena in 4dimensional topology
 10/06/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Brent Nelson (banelson@msu.edu)
In favorable circumstances, topological 4manifolds and surfaces in them can be classified. In contrast, little is known about smooth 4manifolds and smooth surfaces. Several of the hardest problems in 4dimensional topology (eg. the Poincare conjecture) simply ask whether the topological classification fails in the smooth setting; such failures are called exotica. In this talk, I will discuss some historic and recent progress towards detecting exotic phenomena, and outline some promising approaches.

29445

Monday 10/10 3:00 PM

Pavel Čoupek, MSU

Ramification bounds for mod p étale cohomology via prismatic cohomology
 Pavel Čoupek, MSU
 Ramification bounds for mod p étale cohomology via prismatic cohomology
 10/10/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Preston Wake (wakepres@msu.edu)
Let $K/\bf{Q}_p$ be a local number field of absolute ramification index $e$, and let $X$ be a proper smooth $O_K$scheme. I will discuss how one can obtain bounds on ramification of the mod $p$ Galois representations arising as the étale cohomology of (the geometric generic fiber of) $X$ in terms of $e$, the given prime $p>2$ and the cohomological degree $i$. The key tools for achieving this are the BreuilKisin and $A_{\rm inf}$cohomology theories of Bhatt, Morrow and Scholze, and a series of conditions based on a criterion of Gee and Liu regarding crystallinity of the representation attached to a free BreuilKisinFargues $G_K$module.

29422

Monday 10/10 3:00 PM

Vijay Higgins, Michigan State University

TBA
 Vijay Higgins, Michigan State University
 TBA
 10/10/2022
 3:00 PM  4:00 PM
 C204A Wells Hall
 Linhui Shen (shenlin1@msu.edu)
No abstract available.

29440

Monday 10/10 4:00 PM

Lucas Hall, MSU

TBA
 Lucas Hall, MSU
 TBA
 10/10/2022
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
TBA

30448

Tuesday 10/11 11:00 AM

Jacob Gloe, MSU

Diffusion for a Quantum Particle in a Lindbladian Environment with a Periodic Hamiltonian
 Jacob Gloe, MSU
 Diffusion for a Quantum Particle in a Lindbladian Environment with a Periodic Hamiltonian
 10/11/2022
 11:00 AM  12:00 PM
 C304 Wells Hall
 Jeffrey Hudson Schenker (schenke6@msu.edu)
A quantum particle restricted to a lattice of points has been well studied in many different contexts. In the absence of disorder or environmental interaction, the particle simply undergoes ballistic transport for many suitable Hamiltonian operators. Recently, progress has been made on introducing a Lindbladian interaction term to the model, which drastically changes the dynamics in the large time limit. We prove that indeed diffusion is present in this context for an arbitrary periodic Hamiltonian. Additionally, we show that the diffusion constant is inversely proportional to the particles' coupling strength with its environment.

29432

Tuesday 10/11 3:00 PM

Daniel Douglas, Yale

TBA

29437

Thursday 10/13 2:30 PM

Dustin Mixon, Ohio State University

1WMINDS talk (passcode is the first prime number > 100).
 Dustin Mixon, Ohio State University
 1WMINDS talk (passcode is the first prime number > 100).
 10/13/2022
 2:30 PM  3:30 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Mark A Iwen (iwenmark@msu.edu)
See https://sites.google.com/view/mindsseminar/home

29447

Thursday 10/13 3:00 PM

Patricia Hersh, University of Oregon

Generalized recursive atom ordering and equivalence to CLshellability
 Patricia Hersh, University of Oregon
 Generalized recursive atom ordering and equivalence to CLshellability
 10/13/2022
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
When Björner and Wachs introduced one of the main forms of lexicographic shellability, namely CLshellability, they also introduced the notion of recursive atom ordering, and they proved that a finite bounded poset is CLshellable if and only if it admits a recursive atom ordering. We generalize the notion of recursive atom ordering, and we prove that any such generalized recursive atom ordering may be transformed via a reordering process into a recursive atom ordering. We also prove that a finite bounded poset admits a generalized recursive atom ordering if and only if it is ``CCshellable'' by way of a CClabeling which is selfconsistent in a certain sense. This allows us to conclude that CLshellability is equivalent to selfconsistent CCshellability. As an application, we prove that the uncrossing orders, namely the face posets for stratified spaces of planar electrical networks, are dual CLshellable.
During this talk, we will review plenty of background on poset topology and specifically regarding the technique of lexicographic shellability. This is joint work with Grace Stadnyk

30451

Thursday 10/13 3:00 PM

Jie Yang, MSU

Integral modular forms
 Jie Yang, MSU
 Integral modular forms
 10/13/2022
 3:00 PM  4:00 PM
 C204A Wells Hall
 Jie Yang (yangji79@msu.edu)
We'll describe integral aspects of modular form theory, and discuss some applications.

30450

Tuesday 10/18 11:00 AM

Lubashan Pathirana, MSU

TBA
 Lubashan Pathirana, MSU
 TBA
 10/18/2022
 11:00 AM  12:00 PM
 C304 Wells Hall
 Jeffrey Hudson Schenker (schenke6@msu.edu)
No abstract available.

29418

Tuesday 10/18 3:00 PM

Juan MuñozEchániz, Columbia University

TBA
 Juan MuñozEchániz, Columbia University
 TBA
 10/18/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

29390

Wednesday 10/19 4:10 PM

Katherine Zhiyuan Zhang, Courant Institute, NYU

Equilibria and stability in VlasovMaxwell equation
 Katherine Zhiyuan Zhang, Courant Institute, NYU
 Equilibria and stability in VlasovMaxwell equation
 10/19/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Willie WaiYeung Wong (wongwil2@msu.edu)
We present results on the stability of equilibria (timeindependent solutions) of the VlasovMaxwell equation. In particular, linear stability criteria for certain classes of equilibria are discussed. We also give a result on the nonlinear stability of an initialboundary value problem for the VlasovPoisson equation.
**Note: speaker will present Virtually. Participants can join in person to view the presentation in C304, or through the Zoom link.**

29420

Thursday 10/20 4:10 PM

Ken Ribet, UC Berkeley

The Unreasonable Effectiveness of Elliptic Curves
 Ken Ribet, UC Berkeley
 The Unreasonable Effectiveness of Elliptic Curves
 10/20/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
If a and b are integers that satisfy a simple nonvanishing
condition, the cubic equation y^2 = x^3 + ax + b defines an elliptic
curve over the field of rational numbers. Elliptic curves have been
studied for millennia and seem to occur all over the place in
mathematics, physics and other sciences. In my talk, I'll explain how a
specific elliptic curve provides the solution to a surprisingly hard "brain
teaser" that had a big run on social media a few years ago.

29434

Friday 10/21 3:00 PM

Ken Ribet, UC Berkeley

Abelian torsion points (note: unusual day)
 Ken Ribet, UC Berkeley
 Abelian torsion points (note: unusual day)
 10/21/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Preston Wake (wakepres@msu.edu)
No abstract available.

29396

Monday 10/24 3:00 PM

Nathan Chen, Columbia University

TBA
 Nathan Chen, Columbia University
 TBA
 10/24/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Laure Flapan (flapanla@msu.edu)
TBA

29384

Thursday 10/27 4:10 PM

Victor Reiner, University of Minnesota

TBA
 Victor Reiner, University of Minnesota
 TBA
 10/27/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
No abstract available.

29443

Monday 10/31 3:00 PM

Stephanie Chan, UMich

TBA
 Stephanie Chan, UMich
 TBA
 10/31/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Preston Wake (wakepres@msu.edu)
No abstract available.

30455

Tuesday 11/1 11:00 AM

Giorgio Young, University of Michigan

TBA
 Giorgio Young, University of Michigan
 TBA
 11/01/2022
 11:00 AM  12:00 PM
 C304 Wells Hall
 Jeffrey Hudson Schenker (schenke6@msu.edu)
No abstract available.

29433

Tuesday 11/1 3:00 PM

Ka Ho Wong, Texas A&M

TBA

29386

Thursday 11/3 4:10 PM

Tasho Kaletha, University of Michigan

TBA
 Tasho Kaletha, University of Michigan
 TBA
 11/03/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
No abstract available.

29399

Monday 11/7 3:00 PM

Qingjing Chen, University of California Santa Barbara

TBA
 Qingjing Chen, University of California Santa Barbara
 TBA
 11/07/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Laure Flapan (flapanla@msu.edu)
TBA

29411

Tuesday 11/8 3:00 PM

Calvin McPhailSnyder , Duke University

TBA
 Calvin McPhailSnyder , Duke University
 TBA
 11/08/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Efstratia Kalfagianni (kalfagia@msu.edu)
No abstract available.

29379

Wednesday 11/9 4:10 PM

Dimitris Vardakis, MSU

Buffon's needle problem for a random planar disklike Cantor set
 Dimitris Vardakis, MSU
 Buffon's needle problem for a random planar disklike Cantor set
 11/09/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
The Favard length of the planar $1/4$corner Cantor set is $0$. Estimates exists about the rate with which the Favard length of the previous steps goes to $0$, but the exact rate of decay is unknown. However, if one considers a random construction of the $1/4$corner Cantor set, things might seem better. In fact, Peres and Solomyak showed that the rate of decay for the average Favard length for the random $1/4$corner Cantor set is of order exactly $1/n$. We show that the rate of decay for a random disklike analogue has again order $1/n$. This suggests that any ``reasonable'' random Cantor set of positive and finite length might decay at the same rate.

29394

Monday 11/14 3:00 PM

Lena Ji, University of Michigan

TBA
 Lena Ji, University of Michigan
 TBA
 11/14/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
No abstract available.

29430

Tuesday 11/15 3:00 PM

LouisHadrien Robert, Université Clermont Auvergne

TBA
 LouisHadrien Robert, Université Clermont Auvergne
 TBA
 11/15/2022
 3:00 PM  4:00 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Vijay B Higgins (higgi231@msu.edu)
TBA

29444

Wednesday 11/16 4:10 PM

Perry Kleinhenz, MSU

TBA
 Perry Kleinhenz, MSU
 TBA
 11/16/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
TBA

29441

Monday 11/21 4:00 PM

Matthew Lorentz, MSU

TBA
 Matthew Lorentz, MSU
 TBA
 11/21/2022
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
TBA

30449

Monday 11/28 3:00 PM

Zijian Yao, University of Chicago

TBA
 Zijian Yao, University of Chicago
 TBA
 11/28/2022
 3:00 PM  4:00 PM
 C304 Wells Hall
 Preston Wake (wakepres@msu.edu)
No abstract available.

29431

Tuesday 11/29 11:00 AM

Renaud Requipas, NYU

TBA
 Renaud Requipas, NYU
 TBA
 11/29/2022
 11:00 AM  12:00 PM
 C304 Wells Hall
 Jeffrey Hudson Schenker (schenke6@msu.edu)
No abstract available.

29448

Tuesday 11/29 3:00 PM

Justin Lanier, University of Chicago

TBA
 Justin Lanier, University of Chicago
 TBA
 11/29/2022
 3:00 PM  4:00 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

29385

Wednesday 11/30 4:10 PM

Leonardo Abbrescia, Vanderbilt University

TBA
 Leonardo Abbrescia, Vanderbilt University
 TBA
 11/30/2022
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
TBA (likely virtual)

30446

Tuesday 12/6 3:00 PM

Cameron Gates Rudd, Max Planck Institute, Bonn

TBA
 Cameron Gates Rudd, Max Planck Institute, Bonn
 TBA
 12/06/2022
 3:00 PM  4:00 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Vijay B Higgins (higgi231@msu.edu)
TBA
