# All Seminars

Show:Title: TBA |
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Seminar: Algebra |

Speaker: Natalie Paquette of Caltech |

Contact: David Zureick-Brown, dzb@mathcs.emory.edu |

Date: 2018-11-27 at 4:00PM |

Venue: W301 |

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Abstract:TBA |

Title: TBA |
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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 |

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Abstract:TBA |

Title: Joint Athens-Atlanta Number Theory Seminar |
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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 |

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Abstract:TBA |

Title: TBA |
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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 |

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Abstract:TBA |

Title: On the Erdos-Gyarfas distinct distances problem with local constraints |
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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 |

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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 Erdoss 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. |

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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 |

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Abstract:TBA |

Title: TBA |
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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 |

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Abstract:TBA |

Title: Moonshine for Finite Groups |
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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 |

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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 |
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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 |

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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 |
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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 |

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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. |