Seminars and Colloquia by Series

Equidistribution of tropical Weierstrass points

Series
Algebra Seminar
Time
Monday, October 8, 2018 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Harry RichmanUniv. of Michigan
The set of (higher) Weierstrass points on a curve of genus g > 1 is an analogue of the set of N-torsion points on an elliptic curve. As N grows, the torsion points "distribute evenly" over a complex elliptic curve. This makes it natural to ask how Weierstrass points distribute, as the degree of the corresponding divisor grows. We will explore how Weierstrass points behave on tropical curves (i.e. finite metric graphs), and explain how their distribution can be described in terms of electrical networks. Knowledge of tropical curves will not be assumed, but knowledge of how to compute resistances (e.g. in series and parallel) will be useful.

A simple proof of a generalization of a Theorem by C.L. Siegel (Part II)

Series
Dynamical Systems Working Seminar
Time
Friday, October 5, 2018 - 15:05 for 1 hour (actually 50 minutes)
Location
Skiles 156
Speaker
Adrian P. BustamanteGeorgia Tech
In this talk I will present a proof of a generalization of a theorem by Siegel, about the existence of an analytic conjugation between an analytic map, $f(z)=\Lambda z +\hat{f}(z)$, and a linear map, $\Lambda z$, in $\mathbb{C}^n$. This proof illustrates a standar technique used to deal with small divisors problems. I will be following the work of E. Zehnder. This is a continuation of last week talk.

Geometry of hyperfields by Jaiung Jun

Series
Algebra Seminar
Time
Friday, October 5, 2018 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Jaiung JunUniversity of Iowa
In this talk, we introduce rather exotic algebraic structures called hyperrings and hyperfields. We first review the basic definitions and examples of hyperrings, and illustrate how hyperfields can be employed in algebraic geometry to show that certain topological spaces (underlying topological spaces of schemes, Berkovich analytification of schemes, and real schemes) are homeomorphic to sets of rational points of schemes over hyperfields.

The Drift Method and Delay-Optimal Scheduling for Data Center Networks in Heavy Traffic

Series
ACO Student Seminar
Time
Friday, October 5, 2018 - 13:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Siva Theja Maguluri ISyE, Georgia Tech
Abstract: Queueing systems are studied in various asymptotic regimes because they are hard to study in general. One popular regime of study is the heavy-traffic regime, when the system is loaded very close to its capacity. Heavy-traffic behavior of queueing systems is traditionally studied using fluid and diffusion limits. In this talk, I will present a recently developed method called the 'Drift Method', which is much simpler, and is based on studying the drift of certain test functions. In addition to exactly characterizing the heavy-traffic behavior, the drift method can be used to obtain lower and upper bounds for all loads. In this talk, I will present the drift method, and its successful application in the context of data center networks to resolve a decade-old conjecture. I will also talk about ongoing work and some open problems. Bio: Siva Theja Maguluri is an Assistant Professor in the School of Industrial and Systems Engineering at Georgia Tech. Before that, he was a Research Staff Member in the Mathematical Sciences Department at IBM T. J. Watson Research Center. He obtained his Ph.D. from the University of Illinois at Urbana-Champaign in Electrical and Computer Engineering where he worked on resource allocation algorithms for cloud computing and wireless networks. Earlier, he received an MS in ECE and an MS in Applied Math from UIUC and a B.Tech in Electrical Engineering from IIT Madras. His research interests include Stochastic Processes, Optimization, Cloud Computing, Data Centers, Resource Allocation and Scheduling Algorithms, Networks, and Game Theory. The current talk is based on a paper that received the best publication in applied probability award, presented by INFORMS Applied probability society.

An Introduction to Spectral Sequences

Series
Student Algebraic Geometry Seminar
Time
Thursday, October 4, 2018 - 13:30 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Daniel MinahanGeorgia Tech
We discuss the construction of spectral sequences and some of their applications to algebraic geometry, including the classic Leray spectral sequence. We will draw a lot of diagrams and try to avoid doing anything involving lots of indices for a portion of the talk.

Strong Chormatic Index on Graphs with Maximal Degree Four

Series
Graph Theory Working Seminar
Time
Wednesday, October 3, 2018 - 16:30 for 1.5 hours (actually 80 minutes)
Location
Skiles 006
Speaker
James AndersonGeorgia Tech
Erdős and Nešetřil conjectured in 1985 that every graph with maximum degree Δ can be strong edge colored using at most (5/4)Δ^2 colors. In this talk we discuss recent progress made in the case of Δ=4, and go through the method used to improve the upper bound to 21 colors, one away from the conjectured 20.

Localization of orthonormal functions in spectral clusters

Series
Math Physics Seminar
Time
Wednesday, October 3, 2018 - 16:00 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Rupert FrankLMU Munich/Caltech
We generalize the Lp spectral cluster bounds of Sogge for the Laplace-Beltrami operator on compact Riemannian manifolds to systems of orthonormal functions. We show that these bounds are optimal on any manifold in a very strong sense. These spectral cluster bounds follow from Schatten-type bounds on oscillatory integral operators and their optimality follows by semi-classical analysis.

A1-enumerative geometry

Series
Geometry Topology Student Seminar
Time
Wednesday, October 3, 2018 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Stephen MckeanGaTech
Many problems in algebraic geometry involve counting solutions to geometric problems. The number of intersection points of two projective planar curves and the number of lines on a cubic surface are two classical problems in this enumerative geometry. Using A1-homotopy theory, one can gain new insights to old enumerative problems. We will outline some results in A1-enumerative geometry, including the speaker’s current work on Bézout’s Theorem.

The Local L^p Brunn-Minkowski inequality for p<1

Series
High Dimensional Seminar
Time
Wednesday, October 3, 2018 - 12:55 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Xingyu ZhuGeorgia Institute of Technology

The n-dimensional L^p Brunn-Minkowski inequality for p<1 , in particular the log-Brunn-Minkowski inequality, is proposed by Boroczky-Lutwak-Yang-Zhang in 2013, based on previous work of Firey and Lutwak . When it came out, it promptly became the major problem in convex geometry. Although some partial results on some specific convex sets are shown to be true, the general case stays wide open. In this talk I will present a breakthrough on this conjecture due to E. Milman and A Kolesnikov, where we can obeserve a beautiful interaction of PDE, operator theory, Riemannian geometry and all sorts of best constant estimates. They showed the validity of the local version of this inequality for orgin-symmtric convex sets with a C^{2} smooth boundary and strictly postive mean curvature, and for p between 1-c/(n^{3/2}) and 1. Their infinitesimal formulation of this inequality reveals the deep connection with the poincare-type inequalities. It turns out, after a sophisticated transformation, the desired inequality follows from an estimate of the universal constant in Poincare inequality on convex sets.

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