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Stochastics Seminar: Shankar Bhamidi, UNC at Chapel Hill, Dynamic networks and stochastic approximation

SAS 4201

 Models for networks that evolve and change over time are ubiquitous in a host of domains including modeling social networks, understanding the evolution of systems in proteomics, the study of the growth and spread of epidemics etc. This talk will give a brief summary of three recent findings in this area where stochastic approximation techniques…

Applied Math Graduate Student Seminar – Introductory and Organizational Meeting

SAS 4201

If you are interested in learning more about applied math research from your fellow students, or you want a friendly and constructive environment to practice presenting your own research, AMGSS is for you! This is an informational and sign-up meeting, so come to learn more about AMGSS and/or to sign up to present your research.

Geometry and Topology: Peter McGrath, NC State, New Minimal Surfaces in B^3

SAS 4201

A fundamental question in Differential Geometry which has spurred much recent work is whether every orientable compact surface with boundary can be minimally embedded in the Euclidean 3-ball with free boundary.  I will discuss work (joint with M. Karpukhin, R. Kusner, and D. Stern)  which resolves this problem.

Teaching and Learning Seminar: Catie Acitelli, Notre Dame, The Development and Implementation of New Applied Math Curricula


 Computational and applied mathematics are growing in popularity and relevance.  As students prepare for either the job market or graduate school, it is increasingly more important that their mathematics courses reflect the changing landscape of the field.  In this talk, I will detail my development and initial implementation of two new courses: Applied Calculus I…

Computational and Applied Mathematics Seminar: Alexander Kurganov, SUSTech, Central-Upwind Schemes with Reduced Numerical Dissipation

SAS 4201

Central-upwind schemes are Riemann-problem-solver-free Godunov-type finite-volume schemes, which are, in fact, non-oscillatory central schemes with a certain upwind flavor: derivation of the central-upwind numerical fluxes is based on the one-sided local speeds of propagation, which can be estimated using the largest and smallest eigenvalues of the Jacobian. I will introduce two new classes of central-upwind…

Stochastics Seminar: Dominykas Norgilas, NC State, How expensive can an American option be?

SAS 4201

The goal of this talk is to price American-type financial contracts in the presence of Knightian uncertainty. In particular, instead of choosing a particular probabilistic model to represent the price process of some underlying asset (on which an American option is written), we first restrict our attention to the whole class of models that are…

Applied Math Graduate Student Seminar: T.H. Molena Nguyen, NC State, Parallel Recursive Skeletonization Solver for Dense Linear Systems on GPU-Accelerated Computers

SAS 4201

Dense linear systems in large-scale kernel approximation in machine learning, discretization of boundary integral equations in mathematical physics, and low-rank approximation of Schur complements in large sparse matrix factorization often employ a multilevel structure of low-rank off-diagonal blocks. To solve such systems efficiently, we present a GPU-based parallel recursive skeletonization solver that utilizes batched dense…

Biomathematics Seminar: Justin Lessler, UNC, What are planning scenarios for and how can we evaluate them?

Cox 306

As with weather, there is a limit to how far into the future we can accurately forecast the future course of epidemics. Yet, we often need to make plans further into the future than we can reasonably forecast, and in many cases our actions themselves will change the course of an epidemic. One solution to this conundrum is the construction of "planning scenarios" where we project the likely course of an epidemic well beyond the…

Algebra and Combinatorics Seminar: Yupeng Li, Duke University, Coparking functions for matroids

SAS 3282

In Stanley’s seminal work “Cohen-Macaulay Complexes”, Stanley conjectured that all h vectors of matroid complexes are pure O-sequences. We constructed coparking functions on matroids with extra restrictions and showed that the degree sequences of coparking functions are the same as h vectors of matroid complexes. By this construction, we proved that Stanley’s conjecture is true…

Nonlinear Analysis Seminar and Differential Equation Seminar: Thierry Champion, University of Toulon, France,Relaxed multi-marginal costs in optimal transport and quantization effects


 In this talk, I shall present a relaxation formula and duality theory for the multi-marginal Coulomb cost that appears in optimal transport problems arising in Density Functional Theory. The related optimization problems involve probabilities on the entire space and, as minimizing sequences may lose mass at infinity, it is natural to expect relaxed solutions which…

Computational and Applied Mathematics Seminar: Maria Lukacova, the University of Mainz, Uncertainty Quantification for Low Mach Number Flows

SAS 4201

We consider weakly compressible flows coupled with a cloud system that models the dynamics of warm clouds. Our goal is to explicitly describe the evolution of uncertainties that arise due to unknown input data, such as model parameters and initial or boundary conditions. The developed stochastic Galerkin method combines the space-time approximation obtained by a…

Geometry and Topology Seminar: Tony Liimatainen, University of Helsinki, Finland, Geometric inverse problems and inverse problems for the minimal surface equation


We start by giving a short introduction to geometric inverse problems. Then we present our recent results regarding inverse problems for the minimal surface equation. Minimal surfaces are solutions to a quasilinear elliptic equation. We determine a minimal surface up to an isometry from the corresponding Dirichlet-to-Neumann map in dimension 2. Applications of the results…

Algebra and Combinatorics Seminar: Lex Kemper, NC State, Quantum Computing meets Algebra: a physicists’ perspective

SAS 4201

 Quantum hardware has advanced to the point where it is now possible to perform simulations of small physical systems. Although the current capabilities are limited, given the rapid advancement it is an opportune time to develop novel algorithms for the simulation of quantum matter, and to develop those that make it possible to make connections…

Nonlinear Analysis Seminar and Differential Equation Seminar: Russell Luke, Universität Göttingen, Inconsistent Nonconvex Feasibility – Foundations and Application to Orbital Tomography


Feasibility models are a powerful approach to many real-world problems where simply finding a point that comes close enough to meeting many, sometimes contradictory demands is enough. In this talk I will outline the theoretical foundations for the convergence analysis of fixed point iterations of expansive mappings, and show how this specializes to fundamental algorithms…

Teaching and Learning Seminar: Rani Satyam, VCU, Affect Graphing: Tool for understanding students’ confidence, emotion, and experience

SAS 4201

Affect (e.g., beliefs, attitudes, emotions) plays a crucial role in mathematics learning, but reliance on verbal and written responses (from surveys, interviews, etc.) can limit students’ expression of their affective states. As a complement to existing methods, we explore how asking students to graph their affect can be used to study their mathematical experiences. I…

Computational and Applied Mathematics Seminar: Hongkai Zhao, Duke University, Numerical understanding of neural networks: from representation to learning dynamics

SAS 4201

In this talk we present both numerical analysis and experiments to study a few basic computational issues in practice: (1) the numerical error one can achieve given a finite machine precision, (2) the learning dynamics and computation cost to achieve a given accuracy, and (3) stability with respect to perturbations. These issues are addressed for…