**Seminars and Colloquiums**

for the week of February 25, 2019

for the week of February 25, 2019

*SPEAKERS*

**Monday
** Ryan Unger, University of Tennessee

**Wednesday**

Shuler Hopkins and Tamara Riggs, University of Tennessee

Steve Wise, University of Tennessee

**Thursday**

Andrew Papanicolaou, New York University

Cy Maor, University of Toronto

Nicholas Edelen, Massachusetts Institute of Technology

**Friday**

Lindsey Fox and Cara Sulyok, University of Tennessee

MGSC Professional Development Panel

**TEA TIME**

3:00 PM – 3:30 PM

Monday, Tuesday & Wednesday

Room: Ayres 401

Hosted by: Evan Habbershaw & Liam Bitting

Topics: Tips for dissertation writing; preparing for the “Big Day”; weekly check-in (a time for students and faculty to discuss current happenings of the Mathematics Department and share any concerns or ideas).

**Monday, 2/25**

**GEOMETRIC ANALYSIS READING SEMINAR**

TITLE: Fine time extinction of Ricci flow with bubbling off

SPEAKER: Ryan Unger, University of Tennessee

TIME: 3:35 PM-5:30 PM

ROOM: Ayres 113

I will continue with the proof of finite time extinction for irreducible manifolds with nonzero pi_3.

**Wednesday, 2/27**

**ANALYSIS SEMINAR
**TITLE: Counting bi-unimodular sequences of prime length (part 2)

SPEAKER: Shuler Hopkins and Tamara Riggs, University of Tennessee

TIME: 2:30 PM-3:20 PM

ROOM: Ayres 113

An old question of Enflo asks to classify all complex-valued functions f on {0,1,…,n-1}, such that both f and its Fourier transform are unimodular. Such maps, which we will refer to as bi-unimodular sequences, can also be described in terms of circulant Hadamard matrices. We present a paper of Haagerup which counts the number of bi-unimodular sequences of prime length.

**COMPUTATIONAL and APPLIED MATHEMATICS (CAM) SEMINAR**

TITLE: Convergence Analyses of some Nonlinear Multi-Level Algorithms for Non-Quadratic Convex Optimization Problems via Space Decomposition and Subspace Correction, Part III

SPEAKER: Steve Wise, University of Tennessee

TIME: 3:35 PM-4:25 PM

ROOM: Ayres 113

Nonlinear multi-level methods, such as the full approximation storage (FAS) multigrid scheme, are widely used solvers for nonlinear problems. In this paper, a new framework to analyze FAS-type methods for convex optimization problems is developed. FAS can be recast as an inexact version of a nonlinear multigrid method based on space decomposition and subspace correction, namely the successive subspace optimization (SSO) method of Jinchao XU and coauthors. The theory is quite general and is an abstraction of both SSO and the preconditioned steepest descent (PSD) method. In our algorithm, we show that the local problem in each subspace can be simplified to be linear and one gradient decent iteration is enough to ensure linear convergence of the FAS scheme. In Part I, I will introduce the terminology and primary assumptions, and we will give an improved convergence result for SSO in a Hilbert space setting. Then we will motivate and define the generalized FAS algorithm.

This work is joint with Long Chen and Xiaozhe Hu.

**Thursday, 2/28**

**MATHEMATICAL DATA SCIENCE SEMINAR
**TITLE: Reduced Order Representation of Implied Volatility Surfaces

SPEAKER: Andrew Papanicolaou, New York University

TIME: 12:30 PM-2:00 PM

ROOM: Ayres 405

We consider a Principal Component Analysis of implied vol surfaces (IVS) for US equities using data from OptionMetrics which is available through Wharton Research Data Services (WRDS) and specifically address a number of important questions about data of this nature using higher-order decomposition methods for tensor data.

**DIFFERENTIAL EQUATIONS SEMINAR**

TITLE: Elasticity and curvature: the elastic energy of non-Euclidean thin bodies

SPEAKER: Cy Maor, University of Toronto

TIME: 2:10 PM-3:25 PM

ROOM: Ayres 114

Non-Euclidean, or incompatible elasticity, is an elastic theory for bodies that do not have a reference (stress-free) configuration. It applies to many systems, in which the elastic body undergoes plastic deformations or inhomogeneous growth (e.g. plants, self-assembled molecules). Mathematically, it is a question of finding the "most isometric" immersion of a Riemannian manifold (M,g) into Euclidean space of the same dimension, by minimizing an appropriate energy functional.

Much of the research in non-Euclidean elasticity is concerned with elastic bodies that have one or more slender dimensions (such as leaves), and finding appropriate dimensionally-reduced models for them. In this talk I will give an introduction to non-Euclidean elasticity, and then focus on thin bodies and present some recent results on the relations between their elastic behavior and their curvature.

Based on joint work with Asaf Shachar.

**GEOMETRIC ANALYSIS SEMINAR**

TITLE: A global bound for the singular set of area-minimizing hypersurfaces

SPEAKER: Nicholas Edelen, Massachusetts Institute of Technology

TIME: 5:10 PM-6:25 PM

ROOM: Ayres 113

We give an a priori bound on the (n ? 7)-dimensional measure of the singular set for an area-minimizing n-dimensional hypersurface, in terms of the geometry of its boundary.

**Friday, 3/1**

**MATH BIOLOGY SEMINAR
**SPEAKER: Lindsey Fox and Cara Sulyok, University of Tennessee

TIME: 11:15 AM-12:05 PM

ROOM: Ayres 401

In this week's Math Biology seminar, Lindsey Fox and Cara Sulyok will be presenting the paper "Epidemiological Model for Clostridium difficile Transmission in Healthcare Settings" by Dr. Cristina Lanzas (DVM, PhD) et al. of North Carolina State University. (published in Infection Control and Hospital Epidemiology, June 2011, vol. 32, no. 6 pgs. 553-561.). Fox and Sulyok will also be presenting some of their current research which is an expansion on this earlier work of Lanzas and colleagues. Dr. Lanzas will then visit our March 15th seminar to discuss the work in person. If you are interested in being added the Math Biology Seminar 'BaseCamp' site to receive notices and seminar materials directly, please contact Judy Day at judyday@utk.edu.

**COLLOQUIUM**

TITLE: MGSC Professional Development Panel

TIME: 3:35 PM-4:35 PM

ROOM: Ayres 405

At this professional development event for graduate students, a panel of faculty from a variety of areas in the Department will give brief overviews of their research and discuss topics relating to beginning research. The event is hosted by the Math Graduate Student Council.

*If you are interested in giving or arranging a talk
for one of our seminars or colloquiums, please review our
calendar. *

*If you have questions, or a date you would like to confirm,
please contact mlangfo5@utk.edu *

**Past notices:**

Winter Break