Talk_id  Date  Speaker  Title 
31520

Monday 12/19 2:00 PM

Jing Zhou, Penn State University

Application of KAM Theory in the FermiUlam Models (cont'd)
 Jing Zhou, Penn State University
 Application of KAM Theory in the FermiUlam Models (cont'd)
 12/19/2022
 2:00 PM  3:00 PM
 C304 Wells Hall
 Huyi Hu (hhu@msu.edu)
In this talk I’ll briefly introduce the Fermi acceleration problem and some existing results on the subject. In particular, I’ll discuss how KAM theory has been applied in several variants of the FermiUlam models. I’ll also discuss some open problems in this direction.

31514

Monday 1/9 4:10 PM

Anna Weigandt, Massachusetts Institute of Technology

Combinatorial Aspects of Determinantal Varieties
 Anna Weigandt, Massachusetts Institute of Technology
 Combinatorial Aspects of Determinantal Varieties
 01/09/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
Schubert calculus has its origins in enumerative questions asked by the geometers of the 19th century, such as “how many lines meet four fixed lines in threespace?” These problems can be recast as questions about the structure of cohomology rings of geometric spaces such as flag varieties. Borel’s isomorphism identifies the cohomology of the complete flag variety with a simple quotient of a polynomial ring. Lascoux and Schützenberger (1982) defined Schubert polynomials, which are coset representatives for the Schubert basis of this ring. However, it was not clear if this choice was geometrically natural. Knutson and Miller (2005) provided a justification for the naturality of Schubert polynomials via antidiagonal Gröbner degenerations of matrix Schubert varieties, which are generalized determinantal varieties. Furthermore, they showed that preexisting combinatorial objects called pipe dreams govern this degeneration. In this talk, we study the dual setting of diagonal Gröbner degenerations of matrix Schubert varieties, interpreting these limits in terms of the “bumpless pipe dreams” of Lam, Lee, and Shimozono (2021). We then use the combinatorics of Ktheory representatives for Schubert classes to compute the CastelnuovoMumford regularity of matrix Schubert varieties, which gives a bound on the complexity of their coordinate rings.

31527

Tuesday 1/10 2:30 PM


G&T Seminar Organizational Meeting

 G&T Seminar Organizational Meeting
 01/10/2023
 2:30 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

31521

Tuesday 1/10 4:10 PM

Nathaniel Bottman, Max Planck Institute

What analysis, combinatorics, and quilted spheres can tell us about symplectic geometry
 Nathaniel Bottman, Max Planck Institute
 What analysis, combinatorics, and quilted spheres can tell us about symplectic geometry
 01/10/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
A central tool for studying symplectic manifolds is the Fukaya category. In this talk, I will describe my program to relate the Fukaya categories of different symplectic manifolds. The key objects are "witch balls", which are coupled systems of PDEs whose domain is the Riemann sphere decorated with circles and points, and "2associahedra", the configuration spaces of these domains. I will describe applications to symplectic geometry and algebraic geometry, and highlight the role of degenerating families of elliptic PDEs.

31519

Wednesday 1/11 4:10 PM

Aver St. Dizier, University of Illinois

A Polytopal View of Schubert Polynomials
 Aver St. Dizier, University of Illinois
 A Polytopal View of Schubert Polynomials
 01/11/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
Schubert polynomials are a family of multivariable polynomials whose product can be used to solve problems in enumerative geometry. Despite their many known combinatorial formulas, there remain mysteries surrounding these polynomials. I will describe Schubert (and the special case of Schur) polynomials with a focus on polytopes. From this perspective, I will address questions such as vanishing of Schubert coefficients, relative size of coefficients, and interesting properties of their support. Time permitting, I'll talk about my current work on generalizing the Gelfand–Tsetlin polytope, and its connections with representation theory and Bott–Samelson varieties.

31529

Thursday 1/12 2:30 PM

Simon Foucart, Texas A&M University

ZOOM TALK (Passcode: the smallest prime > 100 ): Three uses of semidefinite programming in approximation theory
 Simon Foucart, Texas A&M University
 ZOOM TALK (Passcode: the smallest prime > 100 ): Three uses of semidefinite programming in approximation theory
 01/12/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen (iwenmark@msu.edu)
In this talk, modern optimization techniques are publicized as fitting computational tools to attack several extremal problems from Approximation Theory which had reached their limitations based on purely analytical approaches. Three such problems are showcased: the first problemminimal projectionsinvolves minimization over measures and exploits the moment method; the second problemconstrained approximationinvolves minimization over polynomials and exploits the sumofsquares method; and the third problemoptimal recovery from inaccurate observationsis highly relevant in Data Science and exploits the Sprocedure. In each of these problems, one ends up having to solve semidefinite programs.

31511

Thursday 1/12 4:10 PM

Demetre Kazaras, Duke University

The geometry of scalar curvature and mass in general relativity
 Demetre Kazaras, Duke University
 The geometry of scalar curvature and mass in general relativity
 01/12/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
In general relativity, the space we inhabit is modeled by a Riemannian manifold. The fundamental restriction this theory places upon spatial geometry is a lower bound on this manifold's scalar curvature. It is an important problem in pure geometry to understand the geometric and topological features of this condition. For instance, if a manifold has positive scalar curvature, what may we conclude about the lengths of its curves, the areas of its surfaces, and the topology of the underlying manifold? I will explain many results (originally proven by SchoenYau and GromovLawson) in this direction, and sketch proofs by analyzing objects I call 'spacetime harmonic functions.' Leveraging these new ideas, I will also describe progress on geometric versions of the following questions: How flat is a gravitational system with little total mass? How can we tell when matter will coalesce to form a black hole?

31528

Friday 1/13 4:10 PM

Alexander Watson, University of Minnesota

Mathematics of novel materials from atomic to macroscopic scales
 Alexander Watson, University of Minnesota
 Mathematics of novel materials from atomic to macroscopic scales
 01/13/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
Materials' electronic properties arise from the complex dynamics of electrons flowing through the material. These dynamics are quantum mechanical and present many surprising phenomena without classical analogues. I will present analytical and numerical work clarifying these dynamics in three novel materials which have attracted intense theoretical and experimental attention in recent years: graphene, the first ``2D'' material, whose electronic properties can be captured by an effective Dirac equation, topological insulators, whose edges host surprising oneway edge currents, and twisted bilayer graphene, an aperiodic material whose properties can be captured by an effective system of Dirac equations with periodic coefficients. I will then present ongoing and future work focused on further clarifying the properties of twisted bilayer graphene, which was recently shown to superconduct when twisted to the ``magic'' twist angle 1 degree.

31510

Tuesday 1/17 4:10 PM

Cesar Cuenca, Harvard University

Random matrices and random partitions at varying temperatures
 Cesar Cuenca, Harvard University
 Random matrices and random partitions at varying temperatures
 01/17/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
I will discuss the globalscale behavior of ensembles of random matrix eigenvalues and random partitions which depend on the "inverse temperature" parameter beta. The goal is to convince the audience of the effectiveness of the moment method via Fourierlike transforms in characterizing the Law of Large Numbers and Central Limit Theorems in various settings. We focus on the regimes of high and low temperatures, that is, when the parameter beta converges to zero and infinity, respectively. Part of this talk is based on joint projects with F. BenaychGeorges  V. Gorin, and M. Dolega  A. Moll.

31524

Wednesday 1/18 4:10 PM

Charles Ouyang, UMass Amherst

Compactifications of Hitchin components
 Charles Ouyang, UMass Amherst
 Compactifications of Hitchin components
 01/18/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
Hitchin components are natural generalizations of the classical Teichmüller space. In the setting of SL(3,R), the Hitchin component parameterizes the holonomies of convex real projective structures, which are related to hyperbolic affine spheres. By studying Blaschke metrics, which are Riemannian metrics associated to hyperbolic affine spheres, along with their limits, we obtain a compactification of the SL(3,R)Hitchin component. We show the boundary objects are hybrid structures, which are in part flat metric and in part laminar. These hybrid objects are natural generalizations of measured laminations, which are the boundary objects in Thurston's compactification of Teichmüller space.

31530

Thursday 1/19 2:30 PM

Madeleine Udell, Stanford University

ZOOM TALK (Passcode: the smallest prime > 100 ): Low rank approximation for faster optimization
 Madeleine Udell, Stanford University
 ZOOM TALK (Passcode: the smallest prime > 100 ): Low rank approximation for faster optimization
 01/19/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
Low rank structure is pervasive in realworld datasets. This talk shows how to accelerate the solution of fundamental computational problems, including eigenvalue decomposition, linear system solves, composite convex optimization, and stochastic optimization (including deep learning), by exploiting this low rank structure. We present a simple method based on randomized numerical linear algebra for efficiently computing approximate top eigendecompositions, which can be used to replace large matrices (such as Hessians and constraint matrices) with low rank surrogates that are faster to apply and invert. The resulting solvers for linear systems (NystromPCG), composite convex optimization (NysADMM), and deep learning (SketchySGD) demonstrate strong theoretical and numerical support, outperforming stateoftheart methods in terms of speed and robustness to hyperparameters.

31518

Thursday 1/19 4:10 PM

March Tian Boedihardjo, ETH Zurich

Freeness and matrices
 March Tian Boedihardjo, ETH Zurich
 Freeness and matrices
 01/19/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
I will begin by giving some background on Free Probability motivated by the freeness in free groups. I will then demonstrate how Free Probability can be used to obtain a sharp nonasymptotic random matrix estimate for general use. This talk will be concluded by a recent application of our result to the Matrix Spencer Conjecture. Joint work with Afonso Bandeira and Ramon van Handel.

31552

Friday 1/20 3:00 PM

Fan Yang, Michigan State University

Lorenz attractor and singular flows: expansivity, entropy, and equilibrium states
 Fan Yang, Michigan State University
 Lorenz attractor and singular flows: expansivity, entropy, and equilibrium states
 01/20/2023
 3:00 PM  5:00 PM
 C304 Wells Hall
 Fan Yang (yangfa31@msu.edu)
No abstract available.

31512

Monday 1/23 4:10 PM

Zhongshan An, University of Michigan

Geometric boundary conditions for the Einstein equations and quasilocal mass
 Zhongshan An, University of Michigan
 Geometric boundary conditions for the Einstein equations and quasilocal mass
 01/23/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Sabrina M Walton (waltons3@msu.edu)
The Einstein equations are the most fundamental equations for spacetimes in general relativity. They relate the geometry (curvatures) of a spacetime with its physical property. When a spacetime has nonempty boundary, it is natural to ask what geometric boundary conditions are wellposed for the Einstein equations. The investigation of geometric boundary conditions both gives rise to interesting geometric PDE problems in differential geometry, and also plays an important role in the study of quasilocal mass for compact spacetimes in general relativity. In this talk, we will discuss geometric boundary conditions for the vacuum Einstein equations, from both the hyperbolic and elliptic aspects. Furthermore, we will talk about applications of these geometric boundary value problems in the construction of quasilocal mass.

31551

Tuesday 1/24 1:00 PM

Vince Melfi, MSU; Jenny Green, MSU; John Keane, MSU

Fostering a Culture of Instructional Development in the Department of Statistics and Probability: Our Journey with FirstYear Graduate Teaching Assistants
 Vince Melfi, MSU; Jenny Green, MSU; John Keane, MSU
 Fostering a Culture of Instructional Development in the Department of Statistics and Probability: Our Journey with FirstYear Graduate Teaching Assistants
 01/24/2023
 1:00 PM  2:30 PM
 115 Erickson Hall
 Lisa Keller (kellerl@msu.edu)
How do we support graduate students to teach introductory statistics classes, which themselves are undergoing dramatic transformation? In this talk, we will get to engage with
lessons learned and questions still unanswered as we embarked on the journey of developing an instructional mentoring program for the Department of Statistics and Probability.

31540

Wednesday 1/25 3:00 PM

Wlodzimierz Bryc, University of Cincinnati

Stationary measures of the KardarParisiZhang equation and their limits
 Wlodzimierz Bryc, University of Cincinnati
 Stationary measures of the KardarParisiZhang equation and their limits
 01/25/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Konstantin Matetski (matetski@msu.edu)
I will overview recent results of [Corwin and Knizel, 2021] on the existence of stationary measures for the KPZ equation on an interval and [Barraquand and Le Doussal, 2022], [B.KuznetsovWangWesolowski, 2022] who found two different probabilistic descriptions of the stationary measures as a Markov process and as a measure with explicit RadonNikodym derivative with respect to the Brownian motion. The Markovian description leads to rigorous proofs of some of the limiting results claimed in [Barraquand and Le Doussal, 2022]. I shall discuss how the stationary measures of the KPZ equation on [0,L] behave at large scale as L goes to infinity which according to [Barraquand and Le Doussal, 2022] depending on the normalization, should correspond to stationary measures of a hypothetical KPZ fixed point on [0,1], to the stationary measure for the KPZ equation on the halfline, and to the stationary measure of a hypothetical KPZ fixed point on the halfline.
The talk is based mostly on a joint work with Alexey Kuznetsov (ALEA 2022).

31525

Wednesday 1/25 3:00 PM

Yibo Gao, University of Michigan

CANCELLED: Symmetric structures in the strong Bruhat order
 Yibo Gao, University of Michigan
 CANCELLED: Symmetric structures in the strong Bruhat order
 01/25/2023
 3:00 PM  3:50 PM
 C304 Wells Hall
 Bruce E Sagan (bsagan@msu.edu)
The Bruhat order encodes algebraic and topological information of Schubert varieties in the flag manifold and possesses rich combinatorial properties. In this talk, we discuss three interrelated stories regarding the Bruhat order: selfdual Bruhat intervals, BilleyPostnikov decompositions and automorphisms of the Bruhat graph. This is joint work with Christian Gaetz.

31550

Wednesday 1/25 3:30 PM

Katie Lewis, University of Washington

Disability Equity in Mathematics Education: Accessibility, Remediation, and CompensationAbstract
 Katie Lewis, University of Washington
 Disability Equity in Mathematics Education: Accessibility, Remediation, and CompensationAbstract
 01/25/2023
 3:30 PM  5:00 PM
 252 EH
(Virtual Meeting Link)
 Lisa Keller (kellerl@msu.edu)
Equity in mathematics education research has only recently begun to consider students with disabilities. In this talk, I focus specifically on students with mathematics disabilities – students who have a neurological difference in how their brains process numerical information. Prior research on mathematics disabilities (i.e., dyscalculia) has predominantly taken up a deficit frame, documenting the ways in which students with dyscalculia are deficient in terms of speed and accuracy. In my work, I argue that this deficit orientation is problematic, and I offer an alternative. I take up an explicitly antideficit framing and draw upon sociocultural learning theories and Disability Studies to orient my work. In this talk I use multiple case studies to explore ideas about accessibility, remediation, and compensation across a range of mathematical topics. This antideficit work provides an alternative vantage point to understand disability in mathematics education and suggests avenues to work towards equity. I close by considering ways that mathematics education equity research can be in service of and in partnership with the populations that we study. Zoom option: https://msu.zoom.us/j/95059549382 Passcode: PRIME

31531

Monday 1/30 4:00 PM

Lucas Hall, MSU

Approximately Finite Dimensional C*algebras
 Lucas Hall, MSU
 Approximately Finite Dimensional C*algebras
 01/30/2023
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
I’ll tour through the study of finite dimensional C*algebras and homomorphisms between them, and use this as a basis to define and study approximately finite dimensional (AF) algebras.

31559

Tuesday 1/31 3:00 PM

Theodore Voronov, University of Manchester

From homotopy Lie brackets to thick morphisms of supermanifolds and nonlinear functionalalgebraic duality (NOTE UNUSUAL DAY)
 Theodore Voronov, University of Manchester
 From homotopy Lie brackets to thick morphisms of supermanifolds and nonlinear functionalalgebraic duality (NOTE UNUSUAL DAY)
 01/31/2023
 3:00 PM  4:00 PM
 C204A Wells Hall
 Michael Shapiro (mshapiro@msu.edu)
I will give a motivation for homotopy Lie brackets and the corresponding morphisms preserving brackets "up to homotopy" (more precisely, for Linfinity morphisms and Linfinity algebras), and show how to describe them using supergeometry. So, instead of a single Poisson or Lie bracket, there is a whole sequence of operations with n arguments, n=1,2,3,..., satisfying a linked infinite sequence of identities replacing the familiar Jacobi identity for a Lie bracket; and, instead of a morphism as a linear map mapping a bracket to a bracket, there is a sequence of multilinear mappings mixing brackets with different numbers of arguments, and, in particular, the binary bracket is preserved only up to an (algebraic) homotopy. Geometrically, such a sequence of multilinear mappings assembles into one nonlinear map of supermanifolds.
For the case of homotopy brackets of functions ("higher Poisson" or "homotopy Poisson" structure), this leads us to the question about a natural construction of nonlinear mappings between algebras of smooth functions generalizing the usual pullbacks. I discovered such a construction some years ago. These are "thick morphisms" of (super)manifolds generalizing ordinary smooth maps. From a more general perspective, we arrive in this way at a nonlinear analog of the classical functionalalgebraic duality between spaces and algebras.

31557

Wednesday 2/1 3:00 PM

Stephen Lacina, University of Oregon

Maximal Chain Descent Orders
 Stephen Lacina, University of Oregon
 Maximal Chain Descent Orders
 02/01/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
We introduce a new partial order called the maximal chain descent order on the maximal chains of any finite, bounded poset with an ELlabeling. We prove that the maximal chain descent order encodes via its linear extensions all shellings of the order complex induced by the ELlabeling strictly including the wellknown lexicographic shellings. We show that the standard ELlabeling of the Boolean lattice has maximal chain descent order isomorphic to the type A weak order. We also prove that natural ELlabelings of intervals in Young's lattice give maximal chain descent orders isomorphic to partial orders on the standard Young tableaux or standard skew tableaux of a fixed shape given by swapping certain entries. We additionally show that the cover relations of maximal chain descent orders are generally more subtle than one might first expect, but we characterize the ELlabelings with the expected cover relations including many wellknown families of ELlabelings.

31558

Wednesday 2/1 3:00 PM

Igor Rapinchuk, MSU

Profinite groups and infinite Galois theory
 Igor Rapinchuk, MSU
 Profinite groups and infinite Galois theory
 02/01/2023
 3:00 PM  4:00 PM
 C329 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

31560

Thursday 2/2 2:00 PM

Jie Yang, MSU

Potentially orthonormalizable modules
 Jie Yang, MSU
 Potentially orthonormalizable modules
 02/02/2023
 2:00 PM  3:00 PM
 C204A Wells Hall
 Jie Yang (yangji79@msu.edu)
I will discuss basics of potentially orthonormalizable modules and some related concepts, which are preliminaries for the theory of Fredholm's determinant of compact operators in nonarchimedean setting.

31553

Thursday 2/2 2:30 PM

James Murphy, Tufts University

ZOOM TALK (password the smallest prime > 100)  Towards Intrinsically LowDimensional Models in Wasserstein Space: Geometry, Statistics, and Learning
 James Murphy, Tufts University
 ZOOM TALK (password the smallest prime > 100)  Towards Intrinsically LowDimensional Models in Wasserstein Space: Geometry, Statistics, and Learning
 02/02/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
 Mark A Iwen ()
We consider the problems of efficient modeling and representation learning for probability distributions in Wasserstein space. We consider a general barycentric coding model in which data are represented as Wasserstein2 (W2) barycenters of a set of fixed reference measures. Leveraging the Riemannian structure of W2space, we develop a tractable optimization program to learn the barycentric coordinates when given access to the densities of the underlying measures. We provide a consistent statistical procedure for learning these coordinates when the measures are accessed only by i.i.d. samples. Our consistency results and algorithms exploit entropic regularization of the optimal transport problem, thereby allowing our barycentric modeling approach to scale efficiently. We also consider the problem of learning reference measures given observed data. Our regularized approach to dictionary learning in Wasserstein space addresses core problems of illposedness and in practice learns interpretable dictionary elements and coefficients useful for downstream tasks. Applications to image and natural language processing will be shown throughout the talk.

31535

Monday 2/6 4:00 PM

Aldo Garcia Guinto, MSU

Free Stein dimension of crossed products by finite groups
 Aldo Garcia Guinto, MSU
 Free Stein dimension of crossed products by finite groups
 02/06/2023
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
In this talk, we will discuss a free probabilistic quantity called free Stein dimension and compute it for a crossed product by a finite group. The free Stein dimension is the Murrayvon Neumann dimension of a particular subspace of derivations. Charlesworth and Nelson defined this quantity in the hope of finding a von Neumann algebra invariant. While it is still not known to be a von Neumann algebra invariant, it is an invariant for finitely generated unital tracial *algebras and algebraic methods have been more successful than analytic ones in studying it. Our result continues this trend, and reveals a formula for the free Stein dimension of a crossed product by a finite group that is reminiscint of the Schreier formula for a finite index subgroups of free groups.

31562

Tuesday 2/7 3:30 PM

Amitesh Datta, Princeton University

Does the Jones polynomial of a knot detect the unknot? A novel approach via braid group representations and class numbers of number fields.
 Amitesh Datta, Princeton University
 Does the Jones polynomial of a knot detect the unknot? A novel approach via braid group representations and class numbers of number fields.
 02/07/2023
 3:30 PM  4:30 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Peter Kilgore Johnson (john8251@msu.edu)
How good of an invariant is the Jones polynomial? The question is closely tied to studying braid group representations since the Jones polynomial can be defined as a (normalized) trace of a braid group representation.
In this talk, I will present my work developing a new theory to precisely characterize the entries of classical braid group representations, which leads to a generic faithfulness result for the Burau representation of B_4 (the faithfulness is a longstanding question since the 1930s and is equivalent to whether B_4 is a group of 3 x 3 matrices). In forthcoming work, I use this theory to furthermore explicitly characterize the Jones polynomial of all 3braid closures and generic 4braid closures. I will also describe my work which uses the class numbers of quadratic number fields to show that the Jones polynomial detects the unknot for 3braid links  this work also answers (in a strong form) a question of Vaughan Jones.
I will discuss all of the relevant background from scratch and illustrate my techniques through simple examples.

31563

Wednesday 2/8 3:00 PM

Wenjie Fang, Université Gustave Eiffel

Parabolic Tamari Lattices in Linear Type B
 Wenjie Fang, Université Gustave Eiffel
 Parabolic Tamari Lattices in Linear Type B
 02/08/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
We study parabolic aligned elements associated with the typeB Coxeter group and the socalled linear Coxeter element. These elements were introduced algebraically in (Mühle and Williams, 2019) for parabolic quotients of finite Coxeter groups and were characterized by a certain forcing condition on inversions. We focus on the typeB case and give a combinatorial model for these elements in terms of pattern avoidance. Moreover, we describe an equivalence relation on parabolic quotients of the typeB Coxeter group whose equivalence classes are indexed by the aligned elements. We prove that this equivalence relation extends to a congruence relation for the weak order. The resulting quotient lattice is the typeB analogue of the parabolic Tamari lattice introduced for type A in (Mühle and Williams, 2019). These lattices have not appeared in the literature before. As work in progress, we will also talk about various combinatorial models and bijections between them. Joint work with Henri Mühle and JeanChristophe Novelli.

31567

Wednesday 2/8 3:00 PM

Igor Rapinchuk, MSU

Profinite groups and infinite Galois theory
 Igor Rapinchuk, MSU
 Profinite groups and infinite Galois theory
 02/08/2023
 3:00 PM  4:00 PM
 C329 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

31539

Wednesday 2/8 3:00 PM

Yier Lin, University of Chicago

Some recent progress in the weak noise theory of the KPZ equation
 Yier Lin, University of Chicago
 Some recent progress in the weak noise theory of the KPZ equation
 02/08/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Konstantin Matetski (matetski@msu.edu)
In this talk, we will study the Freidlin–Wentzell LDP for the KPZ equation using the variational principle. Such an approach goes under the name of the weak noise theory in physics. We will explain how to extract various limits of the most probable shape of the KPZ equation in the setting of the Freidlin–Wentzell LDP. Some future directions will also be discussed at the end. The talk is based on several joint works with Pierre Yves Gaudreau Lamarre and LiCheng Tsai.

31564

Wednesday 2/8 4:10 PM

Alexander Volberg, MSU

Noncommutative BohnenblustHille inequalities and application to learning the quantum observables
 Alexander Volberg, MSU
 Noncommutative BohnenblustHille inequalities and application to learning the quantum observables
 02/08/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Willie WaiYeung Wong (wongwil2@msu.edu)
BohnenblustHille inequalities for Boolean cubes have been proven with dimensionfree constants that grow subexponentially in the degree (Defant—Mastylo—Peres). Such inequalities have found great applications in learning low degree Boolean functions (Eskenazis—Ivanisvili). Motivated by learning quantum observables, a quantum counterpart of BohnenblustHille inequality for Boolean cubes was recently conjectured in Cambyse Rouz\’e, Melchior Wirth, and Haonan Zhang: ``Quantum Talagrand, KKL and Friedgut’s theorems and the learnability of quantum Boolean functions.” arXiv preprint, arXiv:2209.07279, 2022.
Haonan Zhang and myself prove such noncommutative BohnenblustHille inequalities with constants that are dimensionfree and of exponential growth in the degree. As applications, we study learning problems of quantum observables.
(Speaker will present remotely)

31561

Thursday 2/9 11:00 AM

Andy Krause, MSU

AI, ChatGPT, and Teaching
 Andy Krause, MSU
 AI, ChatGPT, and Teaching
 02/09/2023
 11:00 AM  12:00 PM
 D101 Wells Hall
 Tsvetanka Sendova (tsendova@msu.edu)
No abstract available.

31568

Thursday 2/9 2:10 PM

Peikai Qi, MSU

Banach space over Qp
 Peikai Qi, MSU
 Banach space over Qp
 02/09/2023
 2:10 PM  3:10 PM
 C204A Wells Hall
 Peikai Qi (qipeikai@msu.edu)
No abstract available.

31569

Thursday 2/9 2:30 PM

Elizabeth Munch, MSU

ZOOM TALK (password the smallest prime > 100)  Combining network analysis and persistent homology for classifying behavior of time series
 Elizabeth Munch, MSU
 ZOOM TALK (password the smallest prime > 100)  Combining network analysis and persistent homology for classifying behavior of time series
 02/09/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen (iwenmark@msu.edu)
Persistent homology, the flagship method of topological data analysis, can be used to provide a quantitative summary of the shape of data. One way to pass data to this method is to start with a finite, discrete metric space (whether or not it arises from a Euclidean embedding) and to study the resulting filtration of the Rips complex. In this talk, we will discuss several available methods for turning a time series into a discrete metric space, including the Takens embedding, $k$nearest neighbor networks, and ordinal partition networks. Combined with persistent homology and machine learning methods, we show how this can be used to classify behavior in time series in both synthetic and experimental data.

31566

Thursday 2/9 3:00 PM

Fan Yang, Michigan State University

Foliations and transverse invariant measures from a dynamical systems point of view
 Fan Yang, Michigan State University
 Foliations and transverse invariant measures from a dynamical systems point of view
 02/09/2023
 3:00 PM  4:00 PM
 C117 Wells Hall
 Fan Yang (yangfa31@msu.edu)
In this talk, we will discuss foliations and their transverse invariant measures (i.e., measures on crosssections that are invariant under the holonomy maps) from a dynamical systems point of view. We will show that for a large family of diffeomorphisms, the unstable foliations admit families of transverse measures that are naturally related to certain probability measures invariant under the dynamics. Given an unstable leaf, we will consider a dynamically defined average that captures its intersection with crosssections and prove that this averaging will converge exponentially fast to the transverse invariant measures. This is a joint work with Ures, Viana and J. Yang.

31578

Monday 2/13 12:30 PM

Chen Zhang, MSU

GAUSS: Construct 3Manifolds with Bagels
 Chen Zhang, MSU
 GAUSS: Construct 3Manifolds with Bagels
 02/13/2023
 12:30 PM  1:30 PM
 C304 Wells Hall
 Chris David St Clair (stclai22@msu.edu)
Abstract: Any closed compact 3 manifold admits a Heegaard splitting, which splits the 3 manifold into two handlebodies. In this talk, we will use bagels to illustrate the idea of Heegaard splitting. More specifically, we will use 2 bagels to construct 3 sphere and finite many bagels to construct any 3 manifold. Besides, bagels will be provided during the talk.

31523

Monday 2/13 3:00 PM

Keerthi Madapusi, Boston College

Derived cycles on Shimura varieties
 Keerthi Madapusi, Boston College
 Derived cycles on Shimura varieties
 02/13/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Georgios Pappas (pappasg@msu.edu)
I’ll explain how methods from derived algebraic geometry can be applied to give a uniform definition of special cycle classes on integral models of Shimura varieties of Hodge type, verifying some consequences of Kudla’s conjectures on the modularity of generating series of cycles on Shimura varieties of Hermitian type.

31504

Tuesday 2/14 2:00 PM

Renaud Detcherry, Institut de Mathématiques de Bourgogne

Title: On the kernel of WittenReshetikhinTuraev quantum representations
 Renaud Detcherry, Institut de Mathématiques de Bourgogne
 Title: On the kernel of WittenReshetikhinTuraev quantum representations
 02/14/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Efstratia Kalfagianni (kalfagia@msu.edu)
Abstract: WittenReshetikhinTuraev SO(3) quantum representations are a family of representations of mapping class groups of surfaces. The family is asymptotically faithful, but each representation has kernel: indeed, rth powers of Dehn twists are in the kernel of the level r quantum representation.
An open question is whether the kernel is generated by rth powers of Dehn twists; we will present partial results on this question, by relating the socalled "hadic expansion" of quantum representations to Johnson homomorphisms.

31574

Wednesday 2/15 3:00 PM

Frank Sottile, Texas A and M Univeristy

CANCELLED: A MurnaghanNakayama formula in quantum Schubert calculus
 Frank Sottile, Texas A and M Univeristy
 CANCELLED: A MurnaghanNakayama formula in quantum Schubert calculus
 02/15/2023
 3:00 PM  3:50 PM
 C517 Wells Hall
 Bruce E Sagan (bsagan@msu.edu)
The MurnaghanNakayama formula expresses the product of a
Schur function with a Newton power sum in the basis of Schur
functions. An important generalization of Schur functions are
Schubert polynomials (both classical and quantum). For these, a
MurnaghanNakayama formula is geometrically meaningful. In
previous work with Morrison, we established a MurnaghanNakayama
formula for Schubert polynomials and conjectured a quantum
version. In this talk, I will discuss some background and then
some recent work proving this quantum conjecture. This is joint
work with Benedetti, Bergeron, Colmenarejo, and Saliola.

31584

Wednesday 2/15 3:00 PM

Igor Rapinchuk, MSU

CANCELLED: Profinite groups and infinite Galois theory
 Igor Rapinchuk, MSU
 CANCELLED: Profinite groups and infinite Galois theory
 02/15/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

31585

Thursday 2/16 2:10 PM

Patel Coupek, MSU

Property (Pr) and completed tensor product
 Patel Coupek, MSU
 Property (Pr) and completed tensor product
 02/16/2023
 2:10 PM  3:10 PM
 C204A Wells Hall
 Peikai Qi (qipeikai@msu.edu)
No abstract available.

31565

Monday 2/20 3:00 PM

Peikai Qi, MSU

Iwasawa lambdainvariants and Massey products
 Peikai Qi, MSU
 Iwasawa lambdainvariants and Massey products
 02/20/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Preston Wake (wakepres@msu.edu)
No abstract available.

31556

Tuesday 2/21 2:00 PM

Ian Montague , Brandeis University

SeibergWitten Floer KTheory and Cyclic Group Actions
 Ian Montague , Brandeis University
 SeibergWitten Floer KTheory and Cyclic Group Actions
 02/21/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
Given a spin rational homology sphere equipped with a cyclic group action, I will introduce equivariant refinements of Manolescu's kappa invariant, derived from the equivariant Ktheory of the SeibergWitten Floer spectrum. These invariants give rise to equivariant relative 10/8ths type inequalities for equivariant spin cobordisms between rational homology spheres. I will explain how these inequalities provide applications to knot concordance, obstruct cyclic group actions on spin fillings, and give genus bounds for knots in punctured 4manifolds. If time permits I will explain how these invariants are related to equivariant etainvariants of the Dirac operator, and describe workinprogress which provides explicit formulas for the $S^1$equivariant etainvariants on Seifertfibered spaces.

31591

Tuesday 2/21 3:00 PM

Francis Bonahon, MSU

The quantum trace for skein algebras of surfaces
 Francis Bonahon, MSU
 The quantum trace for skein algebras of surfaces
 02/21/2023
 3:00 PM  4:00 PM
 C204A Wells Hall
 Michael Shapiro (mshapiro@msu.edu)
The quantum trace homomorphism connects two competing quantizations for the $SL_n$character variety of a surface, consisting of $SL_n$local systems over the surface. The first quantization is through the $SL_n$skein algebra, which is intrinsic but difficult to work with. The second quantization is based on a quantization of ThurstonFockGoncharov local coordinates, and is algebraically easier to handle but depends on choices. I will focus on the construction of this quantum trace in the case where $n=2$.

31576

Tuesday 2/21 4:00 PM

Himchan Jeong, Department of Statistics and Actuarial Science at Simon Fraser University in Canada

Integration of Traditional and Telematics Data for Efficient Insurance Claims Predictions
 Himchan Jeong, Department of Statistics and Actuarial Science at Simon Fraser University in Canada
 Integration of Traditional and Telematics Data for Efficient Insurance Claims Predictions
 02/21/2023
 4:00 PM  5:00 PM
 C304 Wells Hall
 Amanda Nickols (nickols2@msu.edu)
Linked Abstract
While driver telematics has gained attention for risk classification in auto
insurance, scarcity of observations with telematics features has been problematic, which
could be owing to either privacy concern or adverse selection compared to the data points
with traditional features. To handle this issue, we propose a data integration technique based
on calibration weights. It is shown that the proposed technique can efficiently integrate the
socalled traditional data and telematics data and also cope with possible adverse selection
issues on the availability of telematics data. Our findings are supported by a simulation study
and empirical analysis on a synthetic telematics dataset.

31590

Wednesday 2/22 3:00 PM

Igor Rapinchuk, MSU

Cancelled: Profinite groups and infinite Galois theory
 Igor Rapinchuk, MSU
 Cancelled: Profinite groups and infinite Galois theory
 02/22/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

31587

Wednesday 2/22 3:00 PM

Hemanshu Kaul, Illinois Institute of Technology

Polynomials and DPcoloring of Graphs
 Hemanshu Kaul, Illinois Institute of Technology
 Polynomials and DPcoloring of Graphs
 02/22/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
DPcoloring (also called correspondence coloring) of graphs is a generalization of list coloring of graphs that has been widely studied in recent years after its introduction by Dvorak and Postle in 2015. Intuitively, DPcoloring is a variation on list coloring where each vertex in the graph still gets a list of colors, but identification of which colors are different can change from edge to edge. DPcoloring has been investigated from both the extremal (DPchromatic number) and the enumerative (DPcolor function) perspectives.
In this talk, we will give an overview of questions arising with regard to when the DPcolor function equals the chromatic polynomial (or any polynomial), and how the polynomial method, through the Combinatorial Nullstellensatz and the AlonFuredi theorem for the number of nonzeros of a polynomial, can be applied to both extremal and enumerative problems in DPcoloring. Many open problems and conjectures will be presented.

31588

Wednesday 2/22 3:00 PM

Konstantinos Kavvadias , University of Cambridge

Conformal removability of SLE_4
 Konstantinos Kavvadias , University of Cambridge
 Conformal removability of SLE_4
 02/22/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Dapeng Zhan (zhan@msu.edu)
We consider the SchrammLoewner evolution (SLE_kappa) with kappa=4, the critical value of kappa>0 at or below which SLE_kappa is a simple curve and above which it is selfintersecting. We show that the range of an SLE_4 curve is a.s. conformally removable, answering a question posed by Sheffield. In order to establish this result, we give a new sufficient condition for a set X in the complex plane to be conformally removable which applies in the case that X is not necessarily the boundary of a simply connected domain. This is based on a recent joint work with Jason Miller and Lukas Schoug.

32599

Thursday 2/23 2:10 PM

Pavel Coupek, MSU

Property(Pr) and completed tensor product
 Pavel Coupek, MSU
 Property(Pr) and completed tensor product
 02/23/2023
 2:10 PM  3:10 PM
 C204A Wells Hall
 Peikai Qi (qipeikai@msu.edu)
No abstract available.

31570

Thursday 2/23 2:30 PM

Yufeng Liu, University of North Carolina at Chapel Hill

ZOOM TALK (password the smallest prime > 100)  Learning Individualized Treatment Rules with Many Treatments
 Yufeng Liu, University of North Carolina at Chapel Hill
 ZOOM TALK (password the smallest prime > 100)  Learning Individualized Treatment Rules with Many Treatments
 02/23/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
Learning an optimal Individualized Treatment Rule (ITR) is a very important problem in precision medicine. In this talk, we consider the challenge when the number of treatment arms is large, and some groups of treatments in the large treatment space may work similarly for the patients. Motivated by the recent development of supervised clustering, we propose a novel adaptive fusionbased method to cluster the treatments with similar treatment effects together and estimate the optimal ITR simultaneously through a single convex optimization. We establish the theoretical guarantee of recovering the underlying true clustering structure of the treatments for our method. Finally, the superior performance of our method will be demonstrated via both simulations and a real data application on cancer treatment.
This is joint work with Haixu Ma and Donglin Zeng at UNCChapel Hill.

31577

Thursday 2/23 3:00 PM

Zhenqi Wang, Michigan State University

Periodic data and smooth rigidity for hyperbolic automorphisms on torus
 Zhenqi Wang, Michigan State University
 Periodic data and smooth rigidity for hyperbolic automorphisms on torus
 02/23/2023
 3:00 PM  4:00 PM
 A126 Wells Hall
 Fan Yang (yangfa31@msu.edu)
We study the regularity of the conjugacy between an irreducible Anosov automorphism $A$
on torus and its small perturbation $f$.
We say that $f$ and $A$ has the same periodic data if the
derivatives of the return maps of $f$ and $A$ at the corresponding periodic points are
conjugate. We demonstrate that if $f$ is a $C^s$ diffeomorphism with $s$ sufficiently large and has the same periodic data as $A$, then the conjugacy is $C^{s\epsilon}$. This completes the characterization of the most elementary $C^1$invariant for local smooth rigidity.
We also give the first example of cocycle rigidity over fibers with conjugate periodic data.

30460

Thursday 2/23 4:10 PM

Brendan Hassett, Brown University

Rationality in families
 Brendan Hassett, Brown University
 Rationality in families
 02/23/2023
 4:10 PM  5:00 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Joseph Waldron (waldro51@msu.edu)
A smooth complex projective variety is rational if it can be obtained from projective space by algebraic surgeries, i.e. blowups and blowdowns. It is stably rational if it becomes rational after takinga product with some projective space.
Consider a family of such varieties over a connected base. Which members are rational? Stably rational? We focus on recent general results and also outstanding questions that remain. These are illustrated in several key examples, including hypersurfaces of low
degree.
Joint work with Kresch, Pirutka, and Tschinkel.

29395

Friday 2/24 4:00 PM

Yuehaw Khoo, U Chicago

New approaches in simulation of transition paths
 Yuehaw Khoo, U Chicago
 New approaches in simulation of transition paths
 02/24/2023
 4:00 PM  5:00 PM
 C304 Wells Hall
 Mark A Iwen (iwenmark@msu.edu)
Tensor method can be used for compressing highdimensional functions arising from partial differential equations (PDE). In this talk, we focus on using these methods for the simulation of transition processes between metastable states in chemistry applications, for example in molecular dynamics. To this end, we also propose a novel generative modeling procedure using tensornetwork without the use of any optimization.

31589

Monday 2/27 2:00 PM

Nicole Louie, University of WisconsinMadison; Chundou, University of WisconsinMadison

Building Racial Justice in Mathematics Education: A Seat at the Breakfast Table
 Nicole Louie, University of WisconsinMadison; Chundou, University of WisconsinMadison
 Building Racial Justice in Mathematics Education: A Seat at the Breakfast Table
 02/27/2023
 2:00 PM  3:30 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Lisa Keller (kellerl@msu.edu)
Everyone seems to be talking about racial equity and justice these days. Increasingly, scholars in mathematics education are recognizing the need to center the voices of those most affected—i.e., Black, Latine, Asian, and Indigenous children and families—in these discussions. Our current project explores participatory design research (PDR) as a tool for building school, university, student, and parent capacity for centering children of color and their families as researchers and designers of middle school mathematics learning, in a small but diverse Midwestern city. In this talk, we will discuss the challenges we are experiencing and what we are learning about PDR, racial justice, and ourselves, as we work to bring youth of color to the table with us to eat, learn, and act together. Join Zoom Meeting:
https://msu.zoom.us/j/94209936218 Passcode: PRIME

32603

Monday 2/27 2:00 PM

Chamila Malagoda Gamage, MSU

Capacity Constrained Barycenter Problem and its Duality
 Chamila Malagoda Gamage, MSU
 Capacity Constrained Barycenter Problem and its Duality
 02/27/2023
 2:00 PM  3:00 PM
 C329 Wells Hall
(Virtual Meeting Link)
 Craig Gross (grosscra@msu.edu)
The problem of finding a barycenter in the Wasserstein space is a nonlinear interpolation between several probability measures. In this talk we will discuss the notion of barycenters in the Wasserstein space under a capacity constraint on the mass transported and its dual formulation.
$\\$
This will be a hybrid seminar and take place in C329 Wells Hall and via Zoom at https://msu.zoom.us/j/99426648081?pwd=ZEljM3BPUXg2MjVUMVM5TnlzK2NQZz09 .

31532

Monday 2/27 3:00 PM

Michail Savvas, University of Texas

Stabilizer reduction for derived stacks
 Michail Savvas, University of Texas
 Stabilizer reduction for derived stacks
 02/27/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Francois Greer (greerfra@msu.edu)
Suppose that a group acts on a variety. When can the variety and the action be resolved so that all stabilizers are finite? Kirwan gave an answer to this question in the 1980s through an explicit blowup algorithm for smooth varieties with group actions in the context of Geometric Invariant Theory (GIT). In this talk, we will explain how to generalize Kirwan's algorithm to Artin stacks in derived algebraic geometry, which, in particular, include classical, potentially singular, quotient stacks that arise from group actions in GIT. Based on joint work with Jeroen Hekking and David Rydh.

32607

Monday 2/27 4:00 PM

Francis Bonahon, MSU

The quantum trace for skein algebras of surfaces (continued)
 Francis Bonahon, MSU
 The quantum trace for skein algebras of surfaces (continued)
 02/27/2023
 4:00 PM  4:30 PM
 C204A Wells Hall
 Michael Shapiro (mshapiro@msu.edu)
I will discuss the technical details of the construction of the quantum trace homomorphism, going from the SL_2skein algebra to the quantum Teichmüller space of ChekhovFock.

32605

Monday 2/27 4:00 PM

Brent Nelson, MSU

Combinatorics of free probability
 Brent Nelson, MSU
 Combinatorics of free probability
 02/27/2023
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
The lattice of noncrossing partitions plays an important role in the theory of free probability. In particular, it allows one to define the socalled free cumulants, which capture the same information as a noncommutative distribution. In this talk I will provide an introduction to these ideas and show how cumulants offer a characterization of free independence as well as an easy proof of the free central limit theorem.

31547

Tuesday 2/28 2:00 PM

Ryan Stees, Indiana University

Milnor's invariants for knots and links in closed orientable 3manifolds
 Ryan Stees, Indiana University
 Milnor's invariants for knots and links in closed orientable 3manifolds
 02/28/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
Early in his career, John Milnor defined his seminal link invariants, now called Milnor's $\overline{\mu}$invariants. They are topological concordance invariants of links in $S^3$, and much is known about them. However, until recently, few results have extended Milnor's work to links in other closed orientable 3manifolds, and such extensions have done so for special classes of 3manifolds or specific types of links. In this talk, I will discuss an extension of these invariants to concordance invariants of knots and links in any closed orientable 3manifold, discuss some theorems that justify calling them ``Milnor's invariants", and study their properties.

31544

Wednesday 3/1 3:00 PM

Andrei Prokhorov, University of Michigan

Probabilistic approach to Zamolodchikov conjecture for one point conformal blocks on the torus
 Andrei Prokhorov, University of Michigan
 Probabilistic approach to Zamolodchikov conjecture for one point conformal blocks on the torus
 03/01/2023
 3:00 PM  3:50 PM
 C405 Wells Hall
 Konstantin Matetski (matetski@msu.edu)
Liouville field theory is the model for twodimensional quantum gravity. It was constructed rigorously using probabilistic methods by DavidKupiainenRhodesVargas in 2016. According to the conformal bootstrap conjecture npoint correlation functions can be expressed in terms of 3point correlation functions and socalled conformal blocks.
We restrict ourselves to the case of one point correlation function of the Liouville field theory on the torus. We want to study conformal blocks. They are described using complicated asymptotic series. The probabilistic model for them was suggested by GhosalRemySunSun in 2021. It allowed showing that the asymptotic series is actually converging in a small disc.
Liouville field theory has central charge c associated to it. Zamolodchikov in 1984 conjectured that conformal blocks have a limit as c goes to infinity. The limit was called classical conformal blocks. We use the probabilistic formula for conformal blocks to prove Zamolodchikov conjecture and show that the asymptotic series for them is converging in a small disc.
This is joint work with Harini Desiraju and Promit Ghosal.

32608

Wednesday 3/1 3:00 PM

Igor Rapinchuk, MSU

Profinite groups and infinite Galois theory
 Igor Rapinchuk, MSU
 Profinite groups and infinite Galois theory
 03/01/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

32592

Wednesday 3/1 3:00 PM

Sophie Spirkl, University of Waterloo

The Kromatic Symmetric Function
 Sophie Spirkl, University of Waterloo
 The Kromatic Symmetric Function
 03/01/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
The chromatic symmetric function, introduced by Stanley, counts graph colourings, recording the number of vertices of each colour. I will talk about a Ktheoretic analogue of the chromatic symmetric function, in which we are colouring each vertex with a set of colours (rather than a single colour), as well as some results and open questions for this new function. Joint work with Logan Crew and Oliver Pechenik.

31555

Wednesday 3/1 4:10 PM

Zhongshan An, U. Mich

Quasilocal Hamiltonians for compact initial data sets
 Zhongshan An, U. Mich
 Quasilocal Hamiltonians for compact initial data sets
 03/01/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
In general relativity, one of the most interesting ways to construct notions of energy is the method of Hamiltonian analysis. For asymptotically flat spacetimes, this approach yields the wellknown ADM mass. In order to define quasilocal energy/mass for compact initial data sets, one would like to apply the Hamiltonian analysis of GR on compact spacetimes with timelike boundary. Traditionally, this has been done based on fixing the Dirichlet boundary condition of the spacetimes — one of the most wellknown work along this thread is the BrownYork quasilocal mass. In this talk we will discuss in detail the relation between the study of initial boundary value problem for vacuum Einstein equations and the Hamiltonian analysis on compact spacetimes. Then we will construct a notion of quasilocal Hamiltonian (energy) based on a wellposed initial boundary value problem.

32609

Thursday 3/2 2:10 PM

Jie Yang, MSU

Everywhere convergent formal series
 Jie Yang, MSU
 Everywhere convergent formal series
 03/02/2023
 2:10 PM  3:10 PM
 C204A Wells Hall
 Jie Yang (yangji79@msu.edu)
No abstract available.

31571

Thursday 3/2 2:30 PM

Yuejie Chi, Carnegie Mellon University

ZOOM TALK (password the smallest prime > 100)  The Nonasymptotics of Reinforcement Learning
 Yuejie Chi, Carnegie Mellon University
 ZOOM TALK (password the smallest prime > 100)  The Nonasymptotics of Reinforcement Learning
 03/02/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
Reinforcement learning (RL) is garnering significant interest in recent years due to its success in a wide variety of modern applications. However, theoretical understandings on the nonasymptotic sample and computational efficiencies of RL algorithms remain elusive, and are in imminent need to cope with the everincreasing problem dimensions. In this talk, we discuss our recent progress that sheds light on understanding the efficacy of popular RL algorithms in finding the optimal policy in tabular Markov decision processes.

32606

Thursday 3/2 3:00 PM

Huyi Hu, Michigan State University

Quasistability for partially hyperbolic diffeomorphisms
 Huyi Hu, Michigan State University
 Quasistability for partially hyperbolic diffeomorphisms
 03/02/2023
 3:00 PM  4:00 PM
 A126 Wells Hall
 Huyi Hu (hhu@msu.edu)
The motivation of the work is to study topological properties of
partially hyperbolic systems which are similar to those of uniformly hyperbolic systems. We try to obtain some properties similar to these of uniformly hyperbolic systems by ``ignoring'' the motions along the center direction.
We show that any partially hyperbolic systems are quasistable in the sense that for any homeomorphism $g$ $C^0$close to $f$, there exist a continuous map $\pi$ from $M$ to itself and a family of locally defined continuous maps $\{\tau_x\}$, which send points along the center direction, such that
$$\pi\circ g=\tau_{fx}\circ f\circ\pi.
$$
In particular, if $f$ has $C^1$ center foliation, then we can make the motion $\tau$ along the center foliation.
As application we obtain some continuity properties for topological entropy.

29375

Thursday 3/2 4:10 PM

Katy Craig, UCSB

Optimal Transport in Machine Learning and Partial Differential Equations
 Katy Craig, UCSB
 Optimal Transport in Machine Learning and Partial Differential Equations
 03/02/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
Over the past ten years, optimal transport has become a fundamental tool in statistics and machine learning: the 2Wasserstein metric provides a new notion of distance for classifying distributions and a rich geometry for interpolating between them. In parallel, optimal transport has gained mathematical significance by providing new tools for studying stability and limiting behavior of partial differential equations, through the theory of 2Wasserstein gradient flows.
In fact, the success optimal transport in each of these contexts ultimately relies on the same fundamental property of the 2Wasserstein metric: as originally discovered by Otto, the 2Wasserstein metric is unique among classical optimal transport metrics in that it has a formal Riemannian structure. In my talk, I will introduce the theory of optimal transport, explain the special geometric structure of the 2Wasserstein metric, and illustrate the essential role it plays in how optimal transport is used in both machine learning and partial differential equations.

32604

Monday 3/13 1:30 PM

Aditya "Adi" Adiredja, University of Arizona

Journey to “Antideficit Narratives”
 Aditya "Adi" Adiredja, University of Arizona
 Journey to “Antideficit Narratives”
 03/13/2023
 1:30 PM  3:00 PM
 B243 Wells Hall
 Lisa Keller (kellerl@msu.edu)
This talk will be a combination of a meta discussion about how I developed my research program and the main contributions of some of my projects. Specifically, I will share my journey to find a research program that simultaneously engages both equity and cognitive research. I will discuss connections between my work and Funds of Knowledge, as well as other anthropologyinformed work, like Ethnomathematics and studies of the mathematics of Indigenous communities. I will share how one of my current projects with Marta Civil, Project AdeLanTe, implements the principles of antideficit learning
and teaching, while also building on principles from Funds of Knowledge and Culturally Relevant Pedagogy. In Room 252 Erickson and on Zoom: https://msu.zoom.us/j/98177166186
Password: PRIME

30471

Monday 3/13 3:00 PM

Ivan Loseu, Yale University

Unipotent representations and quantization
 Ivan Loseu, Yale University
 Unipotent representations and quantization
 03/13/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
This talk is aimed more at the general audience.
A fundamental question in the representation theory of semisimple Lie groups is to classify their irreducible unitary representations. A guiding principle here is the
Orbit method, first discovered by Kirillov in the 60's for nilpotent Lie groups. It states that the irreducible unitary representations should be related to coadjoint orbits, i.e., the orbits of the Lie group action in the dual of its Lie algebra.
Passing from orbits to representations could be thought of as a quantization problem and it is known that in this setting this is very difficult. For semisimple Lie groups it makes sense to speak about nilpotent orbits, and one could try to study representations that should correspond to these orbits via the yet undefined Orbit method. These representations are called unipotent: they are expected to be nicer than general ones, while one hopes to reduce the study of general representations to that of unipotent ones. I will concentrate on the case of complex Lie groups. I will explain how recent advances in the study of deformation quantizations of singular symplectic varieties allow to define unipotent representations and obtain some results about them. The talk is based on the joint work with Lucas MasonBrown and Dmytro Matvieievskyi.

32596

Monday 3/13 4:00 PM

Matthew Lorentz, MSU

An Introduction to Coarse Geometry
 Matthew Lorentz, MSU
 An Introduction to Coarse Geometry
 03/13/2023
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
In analysis we tend to focus on the "small scale" structure of a space. For example, both derivatives and continuity only depend on a very small neighborhood around a point. Coarse geometry on the other hand focuses on the "large scale" structure of a space. Coarse spaces generalize metric spaces in a way that provides an appropriate framework to study largescale geometry. Coarse geometry is used to study: higher index theory, elliptical operators, the coarse BaumConnes conjecture and as a consiquence the Novikov conjecture.
In this talk we will discuss what a coarse structure is, both in terms of metric spaces and in full generality. Then we will look at a few examples. Next, We will introduce uniform Roe algebras and examine their relationship to coarse structures along with recent advances in solving the rigidity problem. Then, time permitting, we will look at uniform Roe modules.

32597

Tuesday 3/14 10:30 AM

Peixue Wu, University of Illinois Urbana Champaign

Driving open quantum systems to a subspace: stability and large deviations.
 Peixue Wu, University of Illinois Urbana Champaign
 Driving open quantum systems to a subspace: stability and large deviations.
 03/14/2023
 10:30 AM  11:30 AM
 C304 Wells Hall
 Jeffrey Hudson Schenker (schenke6@msu.edu)
Abstract: Preparation of entangled states via engineered open quantum systems is proven to be successful. In our work, we initiate a study of engineered open quantum systems which drive the states to a subspace. In other word, our system will be nonergodic. We prove some stability results and large deviation phenomenon in this setting, under some symmetry condition on the Liouvillian. This is joint work with Marius Junge and Nicholas Laracuente.

31573

Tuesday 3/14 11:30 AM

Shunyu Wan , University of Virginia

Naturality of Legendrian LOSS invariant under positive contact surgery and application
 Shunyu Wan , University of Virginia
 Naturality of Legendrian LOSS invariant under positive contact surgery and application
 03/14/2023
 11:30 AM  12:30 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
Given a Legendrian Knot L in a contact 3 manifold, one can associate a socalled LOSS invariant to L which lives in the knot Floer homology group. We prove that the LOSS invariant is natural under the positive contact surgery. In this talk I will review some background and definition, get the idea of the proof and try to focus on the application which is about new examples of nonsimple knots.

32601

Tuesday 3/14 2:00 PM

John Baldwin, Boston College

Small Dehn surgery and SU(2)representations
 John Baldwin, Boston College
 Small Dehn surgery and SU(2)representations
 03/14/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Matthew Edward Hedden (heddenma@msu.edu)
In their celebrated proof of the Property P Conjecture and its sequel, Kronheimer and Mrowka proved that the fundamental group of rsurgery on a nontrivial knot in the 3sphere admits an irreducible SU(2)representation whenever r is at most 2 in absolute value (which implies in particular that surgery on a nontrivial knot is never a homotopy 3sphere). They asked whether the same is true for other small values of r  in particular, for r = 3 and 4  noting that it's false for r = 5 since 5surgery on the righthanded trefoil is a lens space. I'll describe recent work which answers their question in the affirmative. Our proof involves Floer homology and also the dynamics of surface homeomorphisms. All of this work is joint with Steven Sivek, and significant parts are also joint with Zhenkun Li and Fan Ye.

32613

Wednesday 3/15 3:00 PM

Margaret Bayer, University of Kansas

Simplicial Complexes from Graphs
 Margaret Bayer, University of Kansas
 Simplicial Complexes from Graphs
 03/15/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
Over the last thirty years, there has been various work on simplicial complexes defined from graphs, much from a topological viewpoint. In this talk I will present recent work (with many collaborators) on the topology of two families of simplicial complexes. One is the matching complex, the complex whose faces are sets of edges that form a matching in a graph, with new results on planar graphs coming from certain tilings. The other is the cut complex, where the facets are sets of vertices whose complements induce disconnected graphs.

32614

Wednesday 3/15 3:00 PM

Igor Rapinchuk, MSU

Grothendieck's Galois Theory
 Igor Rapinchuk, MSU
 Grothendieck's Galois Theory
 03/15/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

32620

Thursday 3/16 12:00 PM

Kristen Vroom, MSU; Saul Barbosa, MSU; Tenchita Alzaga Elizondo , Portland State University

Ongoing Efforts to Promote Students' Engagement in Defining
 Kristen Vroom, MSU; Saul Barbosa, MSU; Tenchita Alzaga Elizondo , Portland State University
 Ongoing Efforts to Promote Students' Engagement in Defining
 03/16/2023
 12:00 PM  1:00 PM
 115 Erickson Hall
 Lisa Keller (kellerl@msu.edu)
In this talk, we will share some of our past, present, and future efforts to support students’ defining and conjecturing activity. We will engage in some of the tasks that we are currently implementing with two calculus students. We will also discuss two future directions of our work: optimizing our task design for the whole class setting to promote equitable participation and developing sciencebased motivational tasks that elicit informal ideas about calculus concepts.

32618

Thursday 3/16 2:10 PM

Peikai Qi, MSU

Everywhere convergent formal series and Riesz’s theory II
 Peikai Qi, MSU
 Everywhere convergent formal series and Riesz’s theory II
 03/16/2023
 2:10 PM  3:10 PM
 C204A Wells Hall
 Peikai Qi (qipeikai@msu.edu)
No abstract available.

31579

Thursday 3/16 2:30 PM

Elizabeth Newman, Emory University

ZOOM TALK (password the smallest prime > 100)  A MatrixMimetic Tensor Algebra for Optimal Representations of Multiway Data
 Elizabeth Newman, Emory University
 ZOOM TALK (password the smallest prime > 100)  A MatrixMimetic Tensor Algebra for Optimal Representations of Multiway Data
 03/16/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
Big data has revolutionized the landscape of computational mathematics and has increased the demand for new numerical linear algebra tools to handle the vast amount of data. One crucial task is to efficiently capture inherent structure in data using dimensionality reduction and feature extraction. Tensorbased approaches have gained significant traction in this setting by leveraging multilinear relationships in highdimensional data. In this talk, we will describe a matrixmimetic tensor algebra that offers provably optimal compressed representations of multiway data via a family of tensor singular value decompositions (SVDs). Moreover, using the inherited linear algebra properties of this framework, we will prove that these tensor SVDs outperform the equivalent matrix SVD and two closely related tensor decompositions, the HigherOrder SVD and TensorTrain SVD, in terms of approximation accuracy. Throughout the talk, we will provide numerical examples to support the theory and demonstrate practical efficacy of constructing optimal tensor representations.
This presentation will serve as an overview of our PNAS paper "Tensortensor algebra for optimal representation and compression of multiway data" (https://www.pnas.org/doi/10.1073/pnas.2015851118).

32615

Thursday 3/16 3:00 PM

Fan Yang, MSU

A countable partition for singular flows
 Fan Yang, MSU
 A countable partition for singular flows
 03/16/2023
 3:00 PM  4:00 PM
 A126 Wells Hall
 Fan Yang (yangfa31@msu.edu)
In this talk we consider the entropy theory for singular vector fields with all singularities hyperbolic and nondegenerate. We will construct a countable partition with the property that the metric entropy for any ergodic invariant measure is finite. For singular star flows, we will show that this partition is generating. This is a joint work with Yi Shi and Jiagang Yang.

29404

Thursday 3/16 4:10 PM

John Baldwin, Boston College

Knot detection in Floer homology
 John Baldwin, Boston College
 Knot detection in Floer homology
 03/16/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
A fundamental question for any knot invariant asks which knots it detects (if any). For example, it is famously open whether the Jones polynomial detects the unknot. I'll focus in this talk on the detection question for knot invariants coming from Floer theory and the KhovanovRozansky link homology theories. I'll survey the progress made on this question over the past twenty years, and will gesture at some of the topological ideas that go into my recent work with Sivek. I'll end with applications of our results to problems in Dehn surgery, explaining in particular how we use them to extend some of Gabai's work from the eighties.

32610

Friday 3/17 3:00 PM

Menglun Wang, Food and Drug Administration

Regulatory Perspective on Artificial Intelligence Integrated Drug Development
 Menglun Wang, Food and Drug Administration
 Regulatory Perspective on Artificial Intelligence Integrated Drug Development
 03/17/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Mark A Iwen (iwenmark@msu.edu)
The application of Artificial Intelligence/Machine Learning (AI/ML) in drug development is expanding rapidly. AI/ML have the potential to improve the efficiency of drug development and advance precision medicine. However, there are unique challenges. The presentation will mainly focus on the topic of AI/ML applications in clinical trials, including the following parts:
1. The increasing numbers of submissions over years.
2. Hot therapeutic areas of AI/ML submissions.
3. Types of analysis and objectives in AI/ML in submissions.
4. Case examples.
5. Challenges and outlooks.
In the end of the presentation, opportunities of FDAORISE fellowship will be introduced to senior PhD students.

31533

Friday 3/17 4:00 PM

Terry Haut, Lawerence Livermore National Lab

An Overview of HighOrder Finite Elements for Thermal Radiative Transfer
 Terry Haut, Lawerence Livermore National Lab
 An Overview of HighOrder Finite Elements for Thermal Radiative Transfer
 03/17/2023
 4:00 PM  5:00 PM
 C304 Wells Hall
 Mark A Iwen ()
In this talk, I will give an overview of numerical methods for thermal radiative transfer (TRT), with an emphasis on the use of highorder finite elements for their solution. The TRT equations constitute a (6+1)dimensional set of nonlinear PDEs that describe the interaction of a background material and a radiation field, and their solution is critical for modeling Inertial Confinement Fusion and astrophysics applications. Due to their stiff nature, they are typically discretized implicitly in time, and their solution often accounts for up to 90% of the runtime of multiphysics simulations. I will discuss some recently developed linear solvers, physicsinformed preconditioners, and methods for preserving positivity that are used to make the solution to the TRT equations efficient and robust.

31548

Monday 3/20 2:00 PM

Siddhi Krishna, Columbia University

RTG Seminar: Fibered knots: what, why and how
 Siddhi Krishna, Columbia University
 RTG Seminar: Fibered knots: what, why and how
 03/20/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
Fibered knots show up all over lowdimensional topology, as they provide a robust way to investigate interactions between phenomena of different dimensions. In this talk, I'll survey what they are, why you should care, and how to identify them. Then, as time permits, I'll also sketch a proof that positive braid knots are fibered. I will assume very little background for this talk  all are welcome!

32624

Monday 3/20 2:00 PM

Edem Boahen, MSU

On outer BiLipschitz Extensions of Linear JLmap embeddings of lowdimensional submanifolds of R^n
 Edem Boahen, MSU
 On outer BiLipschitz Extensions of Linear JLmap embeddings of lowdimensional submanifolds of R^n
 03/20/2023
 2:00 PM  3:00 PM
 C329 Wells Hall
(Virtual Meeting Link)
 Craig Gross (grosscra@msu.edu)
Dimensionality reduction is the transformation of data from a highdimensional space into a lowdimensional space so that the lowdimensional representation retains some meaningful properties of the original data, ideally close to its intrinsic dimension.
A classical embedding result is the wellknow “Johnson–Lindenstrauss”. The JL lemma shows how a $n$set of points in $\mathbb{R}^N$ can be embedded into a smaller dimensional space. In this talk we present a result similar to the JLembedding in the interesting case where instead of a discrete set we embed a compact $d$dimensional submanifold $\mathcal{M}$ of $\mathbb{R}^N$ into $\mathbb{R}^m $ where $m$ depends on the volume, reach and dimension of $\mathcal{M}.$
$\\$
This will be a hybrid seminar and take place in C329 Wells Hall and via Zoom at https://msu.zoom.us/j/99426648081?pwd=ZEljM3BPUXg2MjVUMVM5TnlzK2NQZz09 .

31526

Monday 3/20 3:00 PM

John Sheridan, Princeton University

Torelli theorems for certain Steiner bundles on projective space
 John Sheridan, Princeton University
 Torelli theorems for certain Steiner bundles on projective space
 03/20/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Francois Greer (greerfra@msu.edu)
A vector bundle on projective space is called "Steiner" if it can be recognized simply as the cokernel of a map given by a matrix of linear forms. Such maps arise from various geometric setups and one can ask: from the Steiner bundle, can we recover the geometric data used to construct it? In this talk, we will mention an interesting Torellitype result of Dolgachev and Kapranov from 1993 that serves as an origin of this story, as well as other work that this inspired. We'll then indicate our contribution which amounts to analogous Torellitype statements for certain tautological bundles on the very ample linear series of a polarized smooth projective variety. This is joint work with R. Lazarsfeld.

31546

Monday 3/20 4:00 PM

Yoonkyeong Lee, MSU

Fullness of von Neumann algebras through free Fisher information
 Yoonkyeong Lee, MSU
 Fullness of von Neumann algebras through free Fisher information
 03/20/2023
 4:00 PM  5:30 PM
 C517 Wells Hall
 Brent Nelson (banelson@msu.edu)
In classical probability theory, Fisher information is one of the important concepts. Voiculescu introduced the free probability analogue of this quantity, called free fisher information. In this talk, we will discuss how Free Fisher information helps us to understand a von Neumann algebra.

32617

Tuesday 3/21 10:30 AM

Patrick DeBonis, Purdue University

Properties of the Actions and von Neumann algebras of ThompsonLike Groups from Cloning Systems
 Patrick DeBonis, Purdue University
 Properties of the Actions and von Neumann algebras of ThompsonLike Groups from Cloning Systems
 03/21/2023
 10:30 AM  11:20 AM
 C304 Wells Hall
 Brent Nelson (banelson@msu.edu)
Cloning systems are a method for generalizing Thompson's groups, for example $V_d$, that result in a family of groups, $\mathcal{T}_d(G_*)$, whose group von Neumann algebras have been intensely studied by Bashwinger and Zarmesky in recent years. We consider the group actions of a large class of $\mathcal{T}_d(G_*)$ and show they are stable, that is, $G \sim_{OE} G \times \mathbb{Z}.$ As a corollary, we answer Bashwinger and Zaremsky question about when $\mathcal{T}_d(G_*)$ is a McDuff Group in the sense of Deprez and Vaes. As a contrasting result, we show $L(V_d)$ is a prime II$_1$ factor. This is joint work with Rolando de Santiago and Krishnendu Khan.

31549

Tuesday 3/21 11:30 AM

Siddhi Krishna, Columbia University

Twist positivity, Lspace knots, and concordance
 Siddhi Krishna, Columbia University
 Twist positivity, Lspace knots, and concordance
 03/21/2023
 11:30 AM  12:30 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
In this talk, I’ll describe a braid word theoretic property, called “twist positivity”, which often puts strong restrictions on quantitative and geometric properties of a braid. I’ll describe some old and new results about twist positivity, as well as some new applications towards knot concordance. In particular, I’ll describe how using a suite of numerical knot invariants (including the braid index) in tandem allows one to prove that there is an infinite family of Lspace knots (containing all positive torus knots and also an infinite family of hyperbolic knots) where every knot represents a distinct smooth concordance class. This confirms a prediction of the sliceribbon conjecture. Everything I’ll discuss is joint work with Hugh Morton. I will assume little background about knot invariants for this talk – all are welcome!

31538

Tuesday 3/21 2:00 PM

Anup Poudel, Ohio State

A comparison between $SL_n$ spider categories.
 Anup Poudel, Ohio State
 A comparison between $SL_n$ spider categories.
 03/21/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Vijay B Higgins (higgi231@msu.edu)
In this talk, we will explore and make comparisons between various models that exist for spherical tensor categories associated to the category of representations of the quantum group $U_q(sl_n).$ In particular, we will discuss the combinatorial model of MurakamiOhtsukiYamada (MOY), the nvalent ribbon model of Sikora and the trivalent spider category of CautisKamnitzerMorrison (CKM). We conclude by showing that the full subcategory of the spider category from CKM, whose objects are monoidally generated by the standard representation and its dual, is equivalent as a spherical braided category to Sikora's quotient category. This proves a conjecture of Le and Sikora and also answers a question from Morrison's Ph.D. thesis.

32623

Wednesday 3/22 3:00 PM

Marc Gotliboym, MSU

Covering spaces
 Marc Gotliboym, MSU
 Covering spaces
 03/22/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Igor Rapinchuk (rapinchu@msu.edu)
No abstract available.

32619

Wednesday 3/22 3:00 PM

Swee Hong Chan, University of California, Los Angeles

Logconcavity, cross product conjectures, and FKG inequalities in order theory
 Swee Hong Chan, University of California, Los Angeles
 Logconcavity, cross product conjectures, and FKG inequalities in order theory
 03/22/2023
 3:00 PM  3:50 PM
 Online (virtual meeting)
(Virtual Meeting Link)
 Bruce E Sagan (bsagan@msu.edu)
Given a finite poset that is not completely ordered, is it always possible to find two elements x and y, such that the probability that x is less than y in the random linear extension of the poset, is bounded away from 0 and 1? KahnSaks gave an affirmative answer and showed that this probability falls between 3/11 (0.273) and 8/11 (0.727). The currently best known bound is 0.276 and 0.724 by BrightwellFelsnerTrotter, and it is believed that the optimal bound should be 1/3 and 2/3, also known as the 1/32/3 Conjecture. Most notably, logconcave and cross product inequalities played the central role in deriving both bounds. In this talk we will discuss various generalizations of these results together with related open problems. This talk is joint work with Igor Pak and Greta Panova, and is intended for the general audience.

30461

Wednesday 3/22 4:10 PM

Katrina Morgan, Northwestern University

Wave propagation on rotating cosmic string spacetimes
 Katrina Morgan, Northwestern University
 Wave propagation on rotating cosmic string spacetimes
 03/22/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
A rotating cosmic string spacetime has a singularity along a timelike curve corresponding to a onedimensional source of angular momentum. Such spacetimes are not globally hyperbolic: they admit closed timelike curves near the socalled "string". This presents challenges to studying the existence of solutions to the wave equation via conventional energy methods. In this work, we show that forward solutions to the wave equation (in an appropriate microlocal sense) do exist. Our techniques involve proving a statement on propagation of singularities and using the resulting estimates to show existence of solutions. This is joint work with Jared Wunsch.

32625

Thursday 3/23 2:00 PM

Patel Coupek, MSU

Rigid analytic geometry
 Patel Coupek, MSU
 Rigid analytic geometry
 03/23/2023
 2:00 PM  3:00 PM
 C204A Wells Hall
 Peikai Qi (qipeikai@msu.edu)
No abstract available.

31580

Thursday 3/23 2:30 PM

Kasso Okoudjou , Tufts University

ZOOM TALK (password the smallest prime > 100)  The HRT Conjecture: A call for a numerical approach
 Kasso Okoudjou , Tufts University
 ZOOM TALK (password the smallest prime > 100)  The HRT Conjecture: A call for a numerical approach
 03/23/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
The twoscale relation in wavelet analysis dictates that a squareintegrable function can be written as a linear combination of scaled and shifted copies of itself. This fact is equivalent to the existence of squareintegrable functions whose timescale shifts are linearly dependent. By contrast, by replacing the scaling operator with a modulation operator one would think that the linear dependency of the resulting timefrequency shifts of a squareintegrable function might be easily inferred. However, more than two decades after C.~Heil, J.~Ramanatha, and P.~Topiwala conjectured that any such finite collection of timefrequency shifts of a nonzero squareintegrable function on the real line is linearly independent, this problem (the HRT Conjecture) remains unresolved.
The talk will give an overview of the HRT conjecture and introduce an inductive approach to investigate it. I will highlight a few methods that have been effective in solving the conjecture in certain special cases. However, despite the origin of the HRT conjecture in Applied and Computational Harmonic Analysis, there is a lack of experimental or numerical methods to resolve it. I will present an attempt to investigate the conjecture numerically.

32622

Thursday 3/23 3:00 PM

Leonid Rybnikov, HSE and Harvard University

Gaudin model and arc diagrams
 Leonid Rybnikov, HSE and Harvard University
 Gaudin model and arc diagrams
 03/23/2023
 3:00 PM  4:00 PM
 C204A Wells Hall
 Michael Shapiro (mshapiro@msu.edu)
We define a natural, purely geometrical bijection between the set solutions of Bethe ansatz equations for the Gaudin magnet chain and the set of arc diagrams of FrenkelKirillovVarchenko. The former set is in natural bijection with monodromyfree sl_2opers (aka projective structures) on the projective line with the prescribed type of regular singularities at prescribed real marked points (according to Feigin and Frenkel), while the latter indexes the canonical base in a tensor product of U_q(sl_2)modules (via the SchechtmanVarchenko isomorphism). Both sets carry a natural action of the cactus group, i.e., the fundamental group of the real DeligneMumford space of stable rational curves with marked points (by monodromy of solutions to Bethe ansatz equations on the former and by crystal commuters on the latter). We prove that our bijection is compatible with this cactus group action. This is joint work with Nikita Markarian.

29388

Thursday 3/23 4:10 PM

Robin Walters, Northeastern University

Symmetry in Deep Neural Networks
 Robin Walters, Northeastern University
 Symmetry in Deep Neural Networks
 03/23/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
Deep learning has had transformative impacts in many fields including computer vision, computational biology, and dynamics by allowing us to learn functions directly from data. However, there remain many domains in which learning is difficult due to poor model generalization or limited training data. We'll explore two applications of representation theory to neural networks which help address these issues. Firstly, consider the case in which the data represent an $G$equivariant function. In this case, we can consider spaces of equivariant neural networks which may more easily be fit to the data using gradient descent. Secondly, we can consider symmetries of the parameter space as well. Exploiting these symmetries can lead to models with fewer free parameters, faster convergence, and more stable optimization.

32611

Wednesday 3/29 4:10 PM

SungJin Oh, UC Berkeley

TBA
 SungJin Oh, UC Berkeley
 TBA
 03/29/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
TBA

32626

Thursday 3/30 12:00 PM

Woongbae Park, University of Pittsburgh

An integral formula for rational homotopy groups and analytic estimates.
 Woongbae Park, University of Pittsburgh
 An integral formula for rational homotopy groups and analytic estimates.
 03/30/2023
 12:00 PM  1:00 PM
 C304 Wells Hall
 Benjamin I Schmidt (schmi444@msu.edu)
In this talk, I present a rational homotopy group and and its construction using minimal models given by Sullivan.
After briefly describing Sullivan's theorem, I will consider the specific example of S^n v S^n and compute few lowdimensional rational homotopy groups.
In the second part, I introduce the Novikov integral formula for the rational homotopy group and provide analytic bound obtained from the integral formula.
The talk will end with specific examples.

29381

Thursday 3/30 4:10 PM

Tim Hoheisel, McGill University

TBA
 Tim Hoheisel, McGill University
 TBA
 03/30/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

32594

Monday 4/3 3:00 PM

Dan Le, Purdue

TBA
 Dan Le, Purdue
 TBA
 04/03/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Preston Wake (wakepres@msu.edu)
No abstract available.

32598

Tuesday 4/4 10:30 AM

Joe Kraisler, Columbia University

Real Space Quantum Optics in Localized and Periodic Media
 Joe Kraisler, Columbia University
 Real Space Quantum Optics in Localized and Periodic Media
 04/04/2023
 10:30 AM  11:30 AM
 C304 Wells Hall
 Jeffrey Hudson Schenker (schenke6@msu.edu)
We will start by introducing a real space model of a scalar electromagnetic field coupled to a continuum collection of two level atoms. From this we will obtain a pair of nonlocal partial differential equations describing the energy eigenstates that have at most one photon present in the field. The rest of the talk will discuss spectral results in two different types of atomic distributions.
1. Compactly supported densities: In this setting the atoms are contained in a finite region in space. We will state necessary and sufficient conditions for the existence of eigenstates, as well as an upper bound on the number of such states.
2. Periodic densities: In this setting the atoms exhibit the symmetries of a lattice. We will present a decomposition of the continuous spectrum into spectral bands and state a corresponding structure theorem.
This work is joint with Erik Hiltunen, John Schotland, and Michael Weinstein.

31554

Tuesday 4/4 2:00 PM

David Chan, Vanderbilt University

TBA
 David Chan, Vanderbilt University
 TBA
 04/04/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

29400

Wednesday 4/5 4:10 PM

Matt Jacobs, Purdue

TBA
 Matt Jacobs, Purdue
 TBA
 04/05/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

31581

Thursday 4/6 2:30 PM

Alexander Strang, University of Chicago

Strategic Feature Extraction and Low Dimensional Representation of Games  ZOOM TALK (password the smallest prime > 100)
 Alexander Strang, University of Chicago
 Strategic Feature Extraction and Low Dimensional Representation of Games  ZOOM TALK (password the smallest prime > 100)
 04/06/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
Games are widely used to test reinforcement learning paradigms, to study competitive systems in economics and biology, and to model decision tasks. Empirical game theory studies games through observation of populations of interacting agents. We introduce a generic lowdimensional embedding scheme that maps agents into a latent space which enables visualization, interpolation, and strategic feature extraction. The embedding can be used for feature extraction since it represents a generic game as a combination of simpler low dimensional games. Through examples, we illustrate that these components may correspond to basic strategic tradeoffs. We then show that the embedding scheme can represent all games with bounded payout, or whose payout has finite variance when two agents are sampled at random. We develop a formal approximation theory for the representation, study the stability of the embedding, provide sufficient sampling guidelines, and suggest regularizers which promote independence in the identified features.

29382

Thursday 4/6 4:10 PM

Michael Brannan, University of Waterloo

TBA
 Michael Brannan, University of Waterloo
 TBA
 04/06/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

31543

Monday 4/10 2:00 PM

Sam Gunningham, Montana State

RTG Seminar: TBA
 Sam Gunningham, Montana State
 RTG Seminar: TBA
 04/10/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Vijay B Higgins (higgi231@msu.edu)
TBA

32616

Tuesday 4/11 10:30 AM

Eric Roon, University of Arizona

TBA
 Eric Roon, University of Arizona
 TBA
 04/11/2023
 10:30 AM  11:30 AM
 C304 Wells Hall
 Brent Nelson (banelson@msu.edu)
TBA

31542

Tuesday 4/11 2:00 PM

Sam Gunningham, Montana State

TBA
 Sam Gunningham, Montana State
 TBA
 04/11/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Vijay B Higgins (higgi231@msu.edu)
TBA

29385

Wednesday 4/12 4:10 PM

Leonardo Abbrescia, Vanderbilt University

A localized picture of the maximal development for shock forming solutions of the 3D compressible Euler equations
 Leonardo Abbrescia, Vanderbilt University
 A localized picture of the maximal development for shock forming solutions of the 3D compressible Euler equations
 04/12/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Willie WaiYeung Wong (wongwil2@msu.edu)
Understanding the behavior of solutions to the compressible Euler equations for large times necessitates a sharp analysis of possible singularities that can form. Our understanding of shock singularities in three space dimensions has enjoyed a dramatic surge in progress in the past two decades due in part to the mathematical techniques that were developed to study Einstein’s equations. In this talk, I will discuss my recent work which provides a sharp localized description of a shock singularity as part of the boundary of maximal development of smooth data. The set of Cartesian spacetime points on which a singularity occurs, which we call the singular boundary $\mathcal{B}$, has the structure of an embedded hypersurface with very degenerate causal properties. I will give an overview of the difficulties that occur in the construction of the singular boundary, and if time permits, also discuss the construction of the Cauchy horizon which emanates from the past boundary of $\mathcal{B}$.

31582

Thursday 4/13 2:30 PM

Marina Meila , University of Washington

ZOOM TALK (password the smallest prime > 100)  TBA
 Marina Meila , University of Washington
 ZOOM TALK (password the smallest prime > 100)  TBA
 04/13/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
No abstract available.

30453

Thursday 4/13 4:10 PM

David Fisher, Indiana University Bloomington

TBA
 David Fisher, Indiana University Bloomington
 TBA
 04/13/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Olga Turanova (turanova@msu.edu)
TBA

32595

Monday 4/17 10:30 AM

Shiwen Zhang, University of Massachusetts Lowell

TBA
 Shiwen Zhang, University of Massachusetts Lowell
 TBA
 04/17/2023
 10:30 AM  11:30 AM
 C304 Wells Hall
 Jeffrey Hudson Schenker (schenke6@msu.edu)
No abstract available.

31545

Monday 4/17 3:00 PM

Olivier Martin, Stony Brook University

TBA
 Olivier Martin, Stony Brook University
 TBA
 04/17/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Francois Greer (greerfra@msu.edu)
No abstract available.

32612

Tuesday 4/18 2:00 PM

PierreLouis Blayac, University of Michigan

TBA
 PierreLouis Blayac, University of Michigan
 TBA
 04/18/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Vijay B Higgins (higgi231@msu.edu)
TBA

32593

Wednesday 4/19 4:10 PM

Olga Turanova , MSU

TBA
 Olga Turanova , MSU
 TBA
 04/19/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
TBA

29405

Thursday 4/20 4:10 PM

Robert Pollack, Boston University

TBA
 Robert Pollack, Boston University
 TBA
 04/20/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Joseph Waldron (waldro51@msu.edu)
No abstract available.

31505

Friday 4/21 3:00 PM

Jaclyn Lang, Temple

TBA (note unusual day)
 Jaclyn Lang, Temple
 TBA (note unusual day)
 04/21/2023
 3:00 PM  4:00 PM
 C304 Wells Hall
 Preston Wake (wakepres@msu.edu)
No abstract available.

31534

Friday 4/21 4:00 PM

Guosheng Fu, University of Notre Dame

Highorder variational Lagrangian schemes for compressible fluids
 Guosheng Fu, University of Notre Dame
 Highorder variational Lagrangian schemes for compressible fluids
 04/21/2023
 4:00 PM  5:00 PM
 C304 Wells Hall
 Mark A Iwen ()
We present a class of highorder variational Lagrangian schemes for compressible fluids using the tool of energetic variational approach (EnVarA). This is the first time that the EnVarA framework has been applied to non isothermal models where temperature effects are nonnegligible. We illustrate the main idea using the classical ideal gas model, and construct variational Lagrangian schemes that are conservative and entropy stable using EnVarA. Efficient implicit time stepping is designed so that the time step size is not restricted by the sound speed and the model is robust in the low Mach number case. Ample numerical examples will be presented to show the good performance of the proposed schemes for problems including strong shocks, low Mach number flows and multimaterial flows. This is a joint work with Prof. Chun Liu from IIT.

31537

Monday 4/24 2:00 PM

Sarah Petersen, University of Colorado, Boulder

RTG Seminar: TBA
 Sarah Petersen, University of Colorado, Boulder
 RTG Seminar: TBA
 04/24/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

29398

Monday 4/24 3:00 PM

Ján Mináč, University of Western Ontario

TBA
 Ján Mináč, University of Western Ontario
 TBA
 04/24/2023
 3:00 PM  4:00 PM
 Online (virtual meeting)
 Preston Wake (wakepres@msu.edu)
No abstract available.

31575

Tuesday 4/25 10:30 AM

Alex Bols, Caltech

TBA
 Alex Bols, Caltech
 TBA
 04/25/2023
 10:30 AM  11:30 AM
 C304 Wells Hall
 Jeffrey Hudson Schenker (schenke6@msu.edu)
No abstract available.

31536

Tuesday 4/25 2:00 PM

Sarah Petersen, University of Colorado, Boulder

TBA
 Sarah Petersen, University of Colorado, Boulder
 TBA
 04/25/2023
 2:00 PM  3:00 PM
 C304 Wells Hall
 Peter Kilgore Johnson (john8251@msu.edu)
No abstract available.

30452

Wednesday 4/26 4:10 PM

Yakov ShlapentokhRothman, University of Toronto

TBA
 Yakov ShlapentokhRothman, University of Toronto
 TBA
 04/26/2023
 4:10 PM  5:00 PM
 C304 Wells Hall
 Willie WaiYeung Wong (wongwil2@msu.edu)
TBA

31541

Friday 4/28 4:00 PM

Yulong Xing, Ohio State University

TBA
 Yulong Xing, Ohio State University
 TBA
 04/28/2023
 4:00 PM  5:00 PM
 C304 Wells Hall
 Mark A Iwen ()
TBA

31583

Thursday 5/4 2:30 PM

Petros Drineas, Purdue University

ZOOM TALK (password the smallest prime > 100)  TBA
 Petros Drineas, Purdue University
 ZOOM TALK (password the smallest prime > 100)  TBA
 05/04/2023
 2:30 PM  3:30 PM
 C304 Wells Hall
(Virtual Meeting Link)
 Mark A Iwen ()
No abstract available.
