LSU College of Science
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Mathematics

Calendar


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Today, Wednesday, November 13, 2019

Informal Geometry and Topology Seminar  Questions or comments?

Posted September 11, 2019

1:30 pm - 3:00 pm Lockett 233

Abel Lopez, Louisiana State University
TBD

Tomorrow, Thursday, November 14, 2019

Colloquium  Questions or comments?

Posted September 24, 2019
Last modified November 2, 2019

3:30 pm - 4:20 pm Lockett 232

John Voight, Dartmouth College
Heuristics for units in number rings

Units in number rings are gems of arithmetic, the most famous being the golden ratio and the integer solutions x,y to Pell's equation x^2 - D*y^2 = +/-1 for D > 0. Like gems, they are embedded deeply within. Refined questions about the structure of units remain difficult to answer, for example: how often does it happen that Pell's equation has a solution to the -1 equation? More generally, how often in a number ring is it that all totally positive units are squares? Absent theorems, we may still try to predict the answer to these questions. In this talk, we present heuristics (and some theorems!) for signatures of unit groups inspired by the Cohen-Lenstra heuristics for class groups, but involving an lustrous structure of number rings we call the 2-Selmer signature map. This is joint work with David S. Dummit and Richard Foote and with Ben Breen, Noam Elkies, and Ila Varma.

Monday, November 18, 2019

Undergraduate Student Colloquium  

Posted October 15, 2019
Last modified October 16, 2019

TBA

Steven Leth, University of Northern Colorado
TBA


Applied Analysis Seminar  Questions or comments?

Posted November 8, 2019
Last modified November 9, 2019

3:30 pm Lockett 233

F. Alberto Gr¨unbaum, University of California, Berkeley
Quantum walks: a nice playground for old and new mathematics.

I will give an ab-initio talk trying to show how some time honored pieces of analysis can be used to answer questions about recurrence of quantum walks. I will start with a quick review of classical random walks and then show how Schur functions (the same I. Schur of many other deep topics) are useful in the quantum case. Recently these Schur functions have been seen to be useful in getting a topological classification of quantum walks that respect certain symmetries but go beyond the translation invariant case. I will not assume any previous knowledge about quantum walks. This is joint work with Jean Bourgain, Luis Velazquez, Reinhard Werner, Albert Werner and Jon Wilkening.

Tuesday, November 19, 2019

Graduate Student Colloquium  

Posted October 15, 2019
Last modified October 16, 2019

TBA


Steven Leth, University of Northern Colorado
TBA


Algebra and Number Theory Seminar  Questions or comments?

Posted October 11, 2019

3:10 pm - 4:00 pm 285 Lockett

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


Computational Mathematics Seminar  

Posted September 9, 2019
Last modified October 13, 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

Informal Geometry and Topology Seminar  Questions or comments?

Posted September 11, 2019

1:30 pm - 3:00 pm Lockett 233

John Lien, Louisiana State University
TBD


Harmonic Analysis Seminar  Abstract and additional information

Posted August 16, 2019

3:30 pm - 4:20 pm

Tao Mei, Balyor University
TBA

Thursday, November 21, 2019

Colloquium  Questions or comments?

Posted September 10, 2019

3:30 pm - 4:20 pm TBD

Leonid Berlyand, Department of Mathematics, Penn State University
TBD

Monday, November 25, 2019

Applied Analysis Seminar  Questions or comments?

Posted September 6, 2019

3:30 pm - 4:30 pm Lockett 233

Isaac Michael, Louisiana State University
TBA

Tuesday, December 3, 2019

Algebra and Number Theory Seminar  Questions or comments?

Posted October 11, 2019

3:10 pm - 4:00 pm 285 Lockett

Kent Vashaw, Louisiana State University
TBA

Thursday, December 5, 2019

Colloquium  Questions or comments?

Posted September 13, 2019

3:30 pm - 4:20 pm TBD

Eric Rowell, Texas A&M
TBD

Wednesday, March 11, 2020

Geometry and Topology Seminar  Seminar website

Posted November 11, 2019

3:30 pm - 4:30 pm Lockett 233

Zhenkun Li, MIT
TBA