LSU
Mathematics

# Calendar

Time interval:   Events:

Today, Wednesday, October 23, 2019

Posted September 11, 2019

1:30 pm - 3:00 pm Lockett 233

Rima Chatterjee, Louisiana State University
TBD

Posted September 11, 2019

3:30 pm - 4:30 pm Lockett 233

Hung Cong Tran, University of Oklahoma
The local-to-global property for Morse quasi-geodesics

Abstract: We show the mapping class group, CAT(0) groups, the fundamental groups of compact 3-manifolds, and certain relatively hyperbolic groups have a local-to-global property for Morse quasi-geodesics. As a consequence, we generalize combination theorems of Gitik for quasiconvex subgroups of hyperbolic groups to the stable subgroups of these groups. In the case of the mapping class group, this gives a combination theorem for convex cocompact subgroups. This is a joint work with Jacob Russell and Davide Spriano.

Tomorrow, Thursday, October 24, 2019

Posted October 1, 2019

5:30 pm James E. Keisler Lounge (room 321 Lockett)

Actuarial club meeting

West Dickens and Alaina Chifici (LSU alumna) from Protective insurance will visit. They will also set up some interviews for Friday October 25 for anyone applying to their internship program. Pizza will be served.

Tuesday, October 29, 2019

Posted August 19, 2019

3:10 pm - 4:00 pm 285 Lockett

Changningphaabi Namoijam, Texas A&M
Transcendence of Hyperderivatives of Logarithms and Quasi-logarithms of Drinfeld Modules

In 2012, Chang and Papanikolas proved the transcendence of certain logarithms and quasi-logarithms of Drinfeld Modules. We extend this result to transcendence of hyperderivatives of these logarithms and quasi-logarithms. To do this, we construct a suitable t-motive and then use Papanikolas' results on transcendence degree of the period matrix of a t-motive and dimension of its Galois group.

Posted September 13, 2019

3:30 pm - 4:20 pm TBD

Marta Lewicka, University of Pittsburgh
TBD

Wednesday, October 30, 2019

Posted September 11, 2019

1:30 pm - 3:00 pm Lockett 233

Nurdin Takenov, Louisiana State University
TBD

Posted September 9, 2019

3:30 pm - 4:30 pm Lockett 233

Viet Dung Nguyen, Vietnam Academy of Science and Technology Institute of Mathematics
TBD

Thursday, October 31, 2019

Posted October 15, 2019

1:30 pm - 2:30 pm Coates Hall 109

Heuristics for Statistics in Number Theory

Abstract: Last month the sum of three cubes was in the news: mathematicians discovered with a computer how to write 42 as a sum of three cubes and then how to write 3 as a sum of three cubes in a new way; it's in fact expected that both 42 and 3 are a sum of three cubes in infinitely many ways. There are many other patterns in number theory that are expected to occur infinitely often: infinitely many twin primes, infinitely many primes of the form $x^2 + 1$, and so on. The basis for these beliefs is a heuristic way of applying probabilistic ideas to number theory, even though there is nothing probabilistic about perfect cubes or prime numbers. The goal of this talk is to show how such heuristics work and, time permitting, to see a situation where such heuristics break down.

Posted September 13, 2019

3:30 pm - 4:20 pm TBD

Selim Esedoglu , University of Michigan
TBD

Friday, November 1, 2019

Posted October 15, 2019

9:30 am - 10:30 am Allen Hall 123

Applications of Divergence of the Harmonic Series

Abstract: The harmonic series is the sum of all reciprocals $1 + 1/2 + 1/3 + 1/4 + ldots$, and a famous counterintuitive result in calculus is that the harmonic series diverges even though its general term tends to 0. This role for the harmonic series is often the only way students see the harmonic series appear in math classes. However, the divergence of the harmonic series turns out to have applications to topics in math besides calculus and to events in your daily experience. By the end of this talk you will see several reasons that the divergence of the harmonic series should be intuitively reasonable.

Tuesday, November 5, 2019

Posted September 9, 2019

3:30 pm - 4:30 pm 1034 Digital Media Center

Jose Garay, Louisiana State University
Localized Orthogonal Decomposition Method with Additive Schwarz for the Solution of Multiscale Elliptic Problems

Abstract: The solution of elliptic Partial Differential Equations (PDEs) with multiscale diffusion coefficients using regular Finite Element methods (FEM) typically requires a very fine mesh to resolve the small scales, which might be unfeasible. The use of generalized finite elements such as in the method of Localized Orthogonal Decomposition (LOD) requires a coarser mesh to obtain an approximation of the solution with similar accuracy. We present a solver for multiscale elliptic PDEs based on a variant of the LOD method. The resulting multiscale linear system is solved by using a two-level additive Schwarz preconditioner. We provide an analysis of the condition number of the preconditioned system as well as the numerical results which validate our theoretical results.

Wednesday, November 6, 2019

Posted September 11, 2019

1:30 pm - 3:00 pm Lockett 233

Rob Quarles, Louisiana State University
TBD

Posted August 9, 2019

3:30 pm - 4:20 pm TBA

Dejan Slepcev, Carnegie Mellon University
TBA

Posted September 16, 2019

3:30 pm - 4:30 pm Lockett 233

Jason Behrstock, CUNY Graduate Center and Lehman College
TBD

Thursday, November 7, 2019

Posted October 21, 2019

3:30 pm - 4:20 pm TBD

Ignacio Nahuel Zurrian, Universidad Nacional de Cordoba (National University of Cordoba)
TBD

Monday, November 11, 2019

Posted October 5, 2019

3:30 pm - 4:30 pm Lockett Room 233

Matthias Maier, Department of Mathematics Texas A&M University
Simulation of Optical Phenomena on 2D Material Devices

In the terahertz frequency range, the effective (complex-valued) surface conductivity of atomically thick 2D materials such as graphene has a positive imaginary part that is considerably larger than the real part. This feature allows for the propagation of slowly decaying electromagnetic waves, called surface plasmon-polaritons (SPPs), that are confined near the material interface with wavelengths much shorter than the wavelength of the free-space radiation. SPPs are a promising ingredient in the design of novel optical devices, promising "subwavelength optics" beyond the diffraction limit. There is a compelling need for controllable numerical schemes which, placed on firm mathematical grounds, can reliably describe SPPs in a variety of geometries. In this talk we present a number of analytical and computational approaches to simulate SPPs on 2D material interfaces and layered heterostructures. Aspects of the numerical treatment such as absorbing perfectly matched layers, local refinement and a-posteriori error control are discussed. We show analytical results for some prototypical geometries and a homogenization theory for layered heterostructures.

Tuesday, November 12, 2019

Posted October 21, 2019

3:30 pm - 4:20 pm TBD

Nathan Glatt-Holtz, Tulane University
TBD

Wednesday, November 13, 2019

Posted September 11, 2019

1:30 pm - 3:00 pm Lockett 233

Abel Lopez, Louisiana State University
TBD

Thursday, November 14, 2019

Posted September 24, 2019

3:30 pm - 4:20 pm TBD

John Voight, Dartmouth College
TBD

Monday, November 18, 2019

Posted October 15, 2019

TBA

Steven Leth, University of Northern Colorado
TBA

Tuesday, November 19, 2019

Posted October 15, 2019

TBA

Steven Leth, University of Northern Colorado
TBA

Posted October 11, 2019

3:10 pm - 4:00 pm 285 Lockett

Ignacio Nahuel Zurrian, Universidad Nacional de Cordoba (National University of Cordoba)
TBA

Posted September 9, 2019

3:30 pm - 4:30 pm 1034 Digital Media Center

Yakui Huang, Hebei University of Technology
On the Asymptotic Convergence and Acceleration of Gradient Methods

Abstract: We consider the asymptotic behavior of a family of gradient methods, which include the steepest descent and minimal gradient methods as special instances. It is proved that each method in the family will asymptotically zigzag between two directions. Asymptotic convergence results of the objective value, gradient norm, and stepsize are presented as well. To accelerate the family of gradient methods, we further exploit spectral properties of stepsizes to break the zigzagging pattern. In particular, a new stepsize is derived by imposing finite termination on minimizing two dimensional strictly convex quadratic function. It is shown that, for the general quadratic function, the proposed stepsize asymptotically converges to the reciprocal of the largest eigenvalue of the Hessian. Furthermore, based on this spectral property, we propose a periodic gradient method by incorporating the Barzilai-Borwein method. Numerical comparisons with some recent successful gradient methods show that our new method is very promising.

Wednesday, November 20, 2019

Posted September 11, 2019

1:30 pm - 3:00 pm Lockett 233

John Lien, Louisiana State University
TBD

Posted August 16, 2019

3:30 pm - 4:20 pm

Tao Mei, Balyor University
TBA

Thursday, November 21, 2019

Posted September 10, 2019

3:30 pm - 4:20 pm TBD

Leonid Berlyand, Department of Mathematics, Penn State University
TBD

Monday, November 25, 2019

Posted September 6, 2019

3:30 pm - 4:30 pm Lockett 233

Isaac Michael, Louisiana State University
TBA

Tuesday, December 3, 2019

Posted October 11, 2019

3:10 pm - 4:00 pm 285 Lockett

Kent Vashaw, Louisiana State University
TBA

Thursday, December 5, 2019

Posted September 13, 2019

3:30 pm - 4:20 pm TBD

Eric Rowell, Texas A&M
TBD

Monday, January 6, 2020

Posted September 23, 2019

1:00 pm - 4:00 pm Lockett 232

Comprehensive/PhD Qualifying Exam in Topology

This exam is part of the PhD Qualifying Examination in Mathematics. Use this link for the registration form: Comprehensive Exam Registration

Wednesday, January 8, 2020

Posted September 23, 2019

1:00 pm - 4:00 pm Lockett 232

Comprehensive/PhD Qualifying Exam in Analysis

This exam is part of the PhD Qualifying Examination in Mathematics. Use this link for the registration form: Comprehensive Exam Registration

Friday, January 10, 2020

Posted September 23, 2019

1:00 pm - 4:00 pm Lockett 232

Comprehensive/PhD Qualifying Exam in Algebra

This exam is part of the PhD Qualifying Examination in Mathematics. Use this link for the registration form: Comprehensive Exam Registration

Friday, February 7, 2020

Posted August 31, 2019

12:00 pm - 4:00 pm Saturday, February 8, 2020 Digital Media Center Theatre

Scientific Computing Around Louisiana (SCALA 2020)