Seminars and Colloquia by Series

Georgia Scientific Computing Symposium

Series
Applied and Computational Mathematics Seminar
Time
Saturday, February 24, 2018 - 09:30 for 8 hours (full day)
Location
Helen M. Aderhold Learning Center (ALC), Room 24 (60 Luckie St NW, Atlanta, GA 30303)
Speaker
Wenjing Liao and othersGSU, Clemson,UGA, GT, Emory
The Georgia Scientific Computing Symposium is a forum for professors, postdocs, graduate students and other researchers in Georgia to meet in an informal setting, to exchange ideas, and to highlight local scientific computing research. The symposium has been held every year since 2009 and is open to the entire research community. This year, the symposium will be held on Saturday, February 24, 2018, at Georgia State University. More information can be found at: https://math.gsu.edu/xye/public/gscs/gscs2018.html

Brill--Noether theory and determinantal formulas for degeneracy loci

Series
Other Talks
Time
Friday, February 23, 2018 - 17:00 for 1 hour (actually 50 minutes)
Location
Classroom 105 in the D.M. Smith building
Speaker
Associate ProfessorSwarthmore College
Degeneracy loci of morphisms between vector bundles have been used in a wide range of situations, including classical approaches to the Brill--Noether theory of special divisors on curves. I will describe recent developments in Schubert calculus, including K-theoretic formulas for degeneracy loci and their applications to K-classes of Brill--Noether loci. These recover the formulas of Eisenbud--Harris, Pirola, and Chan--López--Pflueger--Teixidor for Brill--Noether curves. This is joint work with Dave Anderson and Nicola Tarasca.

The local limit theorem on nilpotent Lie groups

Series
Combinatorics Seminar
Time
Friday, February 23, 2018 - 15:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Robert HoughSUNY, Stony Brook
I will describe two new local limit theorems on the Heisenberg group, and on an arbitrary connected, simply connected nilpotent Lie group. The limit theorems admit general driving measures and permit testing against test functions with an arbitrary translation on the left and the right. The techniques introduced include a rearrangement group action, the Gowers-Cauchy-Schwarz inequality, and a Lindeberg replacement scheme which approximates the driving measure with the corresponding heat kernel. These results generalize earlier local limit theorems of Alexopoulos and Breuillard, answering several open questions. The work on the Heisenberg group is joint with Persi Diaconis.

Non-existence of Invariant Circles

Series
Dynamical Systems Working Seminar
Time
Friday, February 23, 2018 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 271
Speaker
Jiaqi YangGT Math
We will present a rigorous proof of non-existence of homotopically non-trivial invariant circles for standard map:x_{n+1}=x_n+y_{n+1}; y_{n+1}=y_n+\frac{k}{2\pi}\sin(2\pi x_n).This a work by J. Mather in 1984.

[unusual date and room] Temporal Resolution of Uncertainty and Exhaustible Resource Pricing: A Dynamic Programming Approach

Series
Applied and Computational Mathematics Seminar
Time
Friday, February 23, 2018 - 13:55 for 1 hour (actually 50 minutes)
Location
Skiles 269
Speaker
Prof. Justin KakeuMorehouse University
We use a stochastic dynamic programming approach to address the following question: Can a homogenous resource extraction model (one without extraction costs, without new discoveries, and without technical progress) generate non-increasing resource prices? The traditional answer to that question contends that prices should exhibit an increasing trend as the exhaustible resource is being depleted over time (The Hotelling rule). In contrast, we will show that injecting concerns for temporal resolution of uncertainty in a resource extraction problem can generate a non-increasing trend in the resource price. Indeed, the expected rate of change of the price can become negative if the premium for temporal resolution of uncertainty is negative and outweighs both the positive discount rate and the short-run risk premium. Numerical examples are provided for illustration.

On Polyhedral Homotopy and Matroid Intersection

Series
Student Algebraic Geometry Seminar
Time
Friday, February 23, 2018 - 10:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Tim DuffGeorgia Tech
Polyhedral homotopy methods solve a sparse, square polynomial system by deforming it into a collection of square "binomial start systems." Computing a complete set of start systems is generally a difficult combinatorial problem, despite the successes of several software packages. On the other hand, computing a single start system is a special case of the matroid intersection problem, which may be solved by a simple combinatorial algorithm. I will give an introduction to polyhedral homotopy and the matroid intersection algorithm, with a view towards possible heuristics that may be useful for polynomial system solving in practice.

Covering systems of congruences

Series
School of Mathematics Colloquium
Time
Thursday, February 22, 2018 - 11:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Robert HoughStony Brook University
A distinct covering system of congruences is a finite collection of arithmetic progressions $$a_i \bmod m_i, \qquad 1 < m_1 < m_2 < \cdots < m_k.$$Erdős asked whether the least modulus of a distinct covering system of congruences can be arbitrarily large. I will discuss my proof that minimum modulus is at most $10^{16}$, and recent joint work with Pace Nielsen, in which it is proven that every distinct covering system of congruences has a modulus divisible by either 2 or 3.

An introduction to the braid group.

Series
Geometry Topology Student Seminar
Time
Wednesday, February 21, 2018 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Kevin KodrekGaTech
There are a number of ways to define the braid group. The traditional definition involves equivalence classes of braids, but it can also be defined in terms of mapping class groups, in terms of configuration spaces, or purely algebraically with an explicit presentation. My goal is to give an informal overview of this group and some of its subgroups, comparing and contrasting the various incarnations along the way.

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