Events
Jane Coons, Quasi-Independence Models with Rational Maximum Likelihood Estimator
ZoomLet X and Y be random variables. Quasi-independence models are log-linear models that describe a situation in which some states of X and Y cannot occur together, but X and Y are otherwise independent. We characterize which quasi-independence models have rational maximum likelihood estimator, or MLE, based on combinatorial features of the bipartite graph associated…
Steven Heilman, University of Southern California, Three Candidate Plurality is Stablest for Small Correlations
ZoomSuppose we model n votes in an election between two candidates as n i.i.d. uniform random variables in {-1,1}, so that 1 represents a vote for the first candidate, and -1 represents a vote for the other candidate. Then, for each vote, we flip a biased coin (with fixed probability larger than 1/2 of landing…
Cris Negron, UNC, Cohomology for Drinfeld doubles of finite group schemes
ZoomWe consider a finite group scheme G, and its associated representation category rep G. Here one can think of a finite discrete group, or an infinitesimal group scheme, such as the kernel of the r-th Frobenius map for GL_n over F_p. Via a standard tensor categorical construction one has Drinfeld's center Z(rep G) of the…
Alexander Reznikov, Florida State University, Discrete minimization problems on non-rectifiable sets
ZoomWe survey the known results concerning the minimal Riesz energy on sufficiently smooth sets, and present some new results on fractal sets, which are the key examples of non-rectifiable sets. In particular, we will talk about the connection of these problems to ergodic theory and probability theory: the key step in our proofs is applying…
Anusha Krishnan, Syracuse University, Prescribing Ricci curvature on a product of spheres
ZoomThe Ricci curvature Ric(g) is a symmetric 2-tensor on a Riemannian manifold (M,g) that encodes curvature information. It features in several interesting geometric PDEs such as the Ricci flow and the Einstein equation. The nature of Ric(g) as a differential operator -- nonlinear and degenerate elliptic -- make these equations particularly challenging. Host: Peter McGrath Instructions to join: Zoom…
Tracie Ellis, SIAM Mathematics in Industry Seminar
ZoomZoom link: https://ncsu.zoom.us/j/96495890729?pwd=VUhKZWFKbXBGLy9LVjlJalRsL2RBdz09 Passcode: SIAM Abstract: Join Tracie Ellis, Vice President Business Analytics at Bandwidth, for an informal discussion about her team’s role in creating a data-driven culture at Bandwidth, a software/telecommunications company on Centennial Campus. Tracie will share a bit of background about the company, their data evolution and the qualifications and experience of the Analytics…
Seth Sullivant, How to Give a Terrible Talk
ZoomOrganizer: smsulli2@ncsu.edu
Theresa Anderson, Purdue University, Dyadic analysis (virtually) meets number theory
ZoomIn this talk we discuss two ways in which dyadic analysis and number theory share a rich interaction. The first involves a complete classification of "distinct dyadic systems". These are sets of grids which allow one to compare any Euclidean ball nicely with any dyadic cube, and allow for showing that a large number of…
Jane Coons, NC State, Applications of toric geometry in algebraic statistics
ZoomChair: Seth Sullivant (smsulli2@ncsu.edu, contact for Zoom access)
Silvia Gazzola, University of Bath, Iterative regularization methods for large-scale linear inverse problems
ZoomInverse problems are ubiquitous in many areas of Science and Engineering and, once discretized, they lead to ill-conditioned linear systems, often of huge dimensions: regularization consists in replacing the original system by a nearby problem with better numerical properties, in order to find a meaningful approximation of its solution. After briefly surveying some standard regularization…
Joonas Ilmavirta, Tampere University, Finland, The light ray transform
ZoomWhen is a function in the spacetime uniquely determined by its integrals over all light rays? I will introduce the problem, discuss why we might care about it, and how one might go about proving such uniqueness results. Depending on time and audience interest, I can also discuss proofs and tensor tomography. Organizer: T.…
Rachel Minster, NC State, Randomized algorithms for tensors and matrices with applications
ZoomChair: Arvind Saibaba (asaibab@ncsu.edu, contact for Zoom access)
Jun Yan, NC State, Well-balanced numerical method for atmospheric flow equations with gravity
ZoomChair: Alina Chertock (chertock@math.ncsu.edu, contact for Zoom access)
Helen Cleaves, NC State, Global sensitivity analysis and reducing order modeling for high-dimensional systems
ZoomChair: Alen Alexanderian (alexanderian@ncsu.edu, contact for Zoom access)
Victor Magron, LAAS-CNRS, France, The quest of efficiency and certification in polynomial optimization
ZoomIn 2001, Lasserre introduced a nowadays famous hierarchy of relaxations, called the moment-sums of squares hierarchy, allowing one to obtain a converging sequence of lower bounds for the minimum of a polynomial over a compact semialgebraic set. Each lower bound is computed by solving a semidefinite program (SDP). There are two common drawbacks related to…
Samantha Kirk, NC State, How to Construct Representations of Twisted Toroidal Lie Algebras via Lattice Vertex Algebras
ZoomIf you take a simple finite-dimensional Lie algebra g and tensor it with the Laurent polynomials in one variable, then you will get an infinite-dimensional Lie algebra known as a loop algebra. Affine Lie algebras are the central extensions of such loop algebras and their representations have been of interest to several mathematicians. What happens if we tensor g with…
Mitchel Colebank, NC State, Computational modeling of patient specific pulmonary hemodynamics
ZoomChair: Mette Olufsen (msolufse@ncsu.edu, contact for Zoom access)