# All Seminars

Show:
Title: TBA
Seminar: Algebra
Speaker: Natalie Paquette of Caltech
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2018-11-27 at 4:00PM
Venue: W301
Abstract:
TBA
Title: TBA
Seminar: Algebra
Speaker: Anne Qu\'eguiner-Mathieu of Paris
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2018-10-30 at 4:00PM
Venue: W301
Abstract:
TBA
Title: Joint Athens-Atlanta Number Theory Seminar
Seminar: Algebra
Speaker: Larry Rolen and Bianca Viray of Vanderbilt and University of Washington
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2018-10-23 at 4:00PM
Venue: W301
Abstract:
TBA
Title: TBA
Seminar: Algebra
Speaker: Eva Bayer Fluckinger of EPFL
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2018-10-16 at 4:00PM
Venue: W301
Abstract:
TBA
Title: On the Erdos-Gyarfas distinct distances problem with local constraints
Seminar: Combinatorics
Speaker: Cosmin Pohoata of The California Institute of Technology
Contact: Dwight Duffus, dwightduffus@emory.edu
Date: 2018-10-01 at 4:00PM
Venue: E408
Abstract:
In 1946 Erdos asked to determine or estimate the minimum number of distinct distances determined by an n-element planar point set V. He showed that a square integer lattice determines \Theta(n/\sqrt{log n}) distinct distances, and conjectured that any n-element point set determines at least n^{1−o(1)} distinct distances. In 2010-2015, Guth and Katz answered Erdoss question by proving that any n-element planar point set determines at least \Omega(n/log n) distinct distances. In this talk, we consider a variant of this problem by Erdos and Gyarfas. For integers n, p, q with p \geq q \geq 2, determine the minimum number D(n,p,q) of distinct distances determined by a planar n-element point set V with the property that any p points from V determine at least q distinct distance. In a recent paper, Fox, Pach and Suk prove that when q = {p \choose 2} - p + 6, D(n,p,q) is always at least n^{8/7 - o(1)}. We will discuss a recent improvement of their result and some new bounds for a related (graph theoretic) Ramsey problem of Erdos and Shelah which arise. This is joint work with Adam Sheffer.
Title: TBA
Seminar: Algebra
Speaker: Renee Bell of University of Pennsylvania
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2018-09-25 at 4:00PM
Venue: W301
Abstract:
TBA
Title: TBA
Seminar: Algebra
Speaker: Philipp Jell of Georgia Tech
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2018-09-18 at 4:00PM
Venue: W301
Abstract:
TBA
Title: Moonshine for Finite Groups
Seminar: Algebra
Speaker: Madeline Locus Dawsey of Emory University
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2018-09-11 at 4:00PM
Venue: W301
Abstract:
{\it Weak moonshine} for a finite group $G$ is the phenomenon where an infinite dimensional graded $G$-module $$V_G=\bigoplus_{n\gg-\infty}V_G(n)$$ has the property that its trace functions, known as McKay-Thompson series, are modular functions. Recent work by Dehority, Gonzalez, Vafa, and Van Peski established that weak moonshine holds for every finite group. Since weak moonshine only relies on character tables, which are not isomorphism class invariants, non-isomorphic groups can have the same McKay-Thompson series. We address this problem by extending weak moonshine to arbitrary width $s\in\mathbb{Z}^+$. For each $1\leq r\leq s$ and each irreducible character $\chi_i$, we employ Frobenius' $r$-character extension $\chi_i^{(r)} \colon G^{(r)}\rightarrow\mathbb{C}$ to define McKay-Thompson series of $V_G^{(r)}:=V_G\times\cdots\times V_G$ ($r$ copies) for each $r$-tuple in $G^{(r)}:=G\times\cdots\times G$ ($r$ copies). These series are modular functions. We find that {\it complete} width 3 weak moonshine always determines a group up to isomorphism. Furthermore, we establish orthogonality relations for the Frobenius $r$-characters, which dictate the compatibility of the extension of weak moonshine for $V_G$ to width $s$ weak moonshine.
Title: Research Spotlights
Seminar: Numerical Analysis and Scientific Computing
Speaker: Alessandro Veneziani and Yuanzhe Xi of Emory University
Contact: Lars Ruthotto, lruthotto@emory.edu
Date: 2018-09-07 at 2:00PM
Venue: MSC N302
Abstract:
The scientific computing group at Emory welcomes all for the second round of research spotlights. This week, Dr. Veneziani and Dr. Xi will present their groups work. Dr. Veneziani will give an overview of his work on numerical partial differential equations and their impact on medical decision-making. Dr. Xi will present new and ongoing work in high-performance computing for numerical linear algebra with applications in physics and machine learning. These high-level talks will not be too technical, and faculty and students working in other but related fields are encouraged to attend.
Title: Tropical dual varieties
Seminar: Algebra
Speaker: Yoav Len of Georgia Tech
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2018-09-04 at 4:00PM
Venue: W301
Abstract:
My talk will revolve around combinatorial aspects of dual varieties. I will introduce the tropical dual variety, which similarly to the algebraic case, classifies tangent hyperplanes to a given variety. The construction commutes with tropicalization, and the resulting object is indeed a tropical variety. Consequently, we obtain a combinatorial tool for counting multi-tangent hyperplanes to algebraic varieties, detecting dual defects, and for computing Newton polygons of dual varieties.