All Seminars

Title: On the inertia set of a graph
Seminar: Combinatorics
Speaker: Hein van der Holst of Eindhoven University of Technology
Contact: Dwight Duffus, dwight@mathcs.emory.edu
Date: 2008-09-29 at 4:00PM
Venue: MSC W301
Download Flyer
Abstract:
Title: Graphs on Affine or Linear Points
Seminar: Combinatorics
Speaker: Hanno Lefmann of
Contact: Vojtech Rodl, rodl@mathcs.emory.edu
Date: 2008-09-26 at 4:00PM
Venue: W306
Download Flyer
Abstract:
Motivated by a question of Hajnal on independent finite sum-sets in triangle-free graphs with vertex sets being the set of positive integers we consider the following problem: Given are fixed integers k,l > 0 and a finite field F. Given is any graph G = (V, E) with vertex set being the set of all affine or linear points of an n-dimensional affine or linear vector space over F, where G does not contain a complete graph on l vertices. Is it possible to find a k-dimensional subspace, such that the set of all its affine or linear points forms an independent set in G? Having answered this questions, we give some applications to the corresponding problem for the set of solutions of partition regular systems of linear equations over Abelian groups. This is some joint work with D. Gunderson.
Title: Mass formulas for mod p Galois representations
Colloquium: N/A
Speaker: Chandrashekhar Khare of UCLA
Contact: Parimala Raman, parimala@mathcs.emory.edu
Date: 2008-09-25 at 4:00PM
Venue: MSC W201
Download Flyer
Abstract:
The recent proof of Serre's conjecture allows one to prove the finiteness of certain types of Galois representations (2-dimensional mod $p$, odd, semisimple respresentations of the absolute Galois group of the rationals with bounded prime to $p$ Artin conductor). One may ask for quantitative refinements of this. It seems hard to get a grip on this, although one can formulate a natural expectation. This is in the spirit of the theorem of Hermite-Minskowski which asserts that there are only finitely many extensions of the rationals of bounded discriminant. One can ask for quantitative versions of this: a precise count is again unknown.
Title: A Reflector Design Problem for a Collimated Source
Seminar: N/A
Speaker: Tobias Graf of Emory University
Contact: Vladimir Oliker, oliker@mathcs.emory.edu
Date: 2008-09-23 at 5:00PM
Venue: MSC W301
Download Flyer
Abstract:
We will discuss the following reflector problem. Given a parallel light beam emitted from a bounded domain in a hyperplane of n+1 dimensional Euclidean space and a receiver surface as well as prescribed in advance intensities for the source domain and the receiver, can we design a reflector surface that redistributes the emitted light accordingly?
Title: Making Sense of Genome-scale Data
Graduate Student Seminar: Computer Science
Speaker: Dr. James Taylor of Emory University
Contact: James J. Lu, jlu@mathcs.emory.edu
Date: 2008-09-19 at 3:00PM
Venue: MSC W201
Download Flyer
Abstract:
High-throughput data production technologies are revolutionizing modern biology. Translating this experimental data into discoveries of relevance to human health relies on sophisticated computational tools that can handle large-scale data. However, sophisticated methods for the analysis of biological data are of little value if they are not accessible. Powerful analysis tools, data warehouses, and browsers exist, but for the average experimental biologists with limited computer expertise, making effective use of these resources is still out of reach. We have developed "Galaxy", which solves this problem by providing an integrated web-based workspace that bridges the gap between different tools and data sources. For computational tool developers, Galaxy eliminates the repetitive effort involved in creating high-quality user interfaces, while giving them the benefit of being able to provide their tools in an integrated environment. For experimental biologists, Galaxy allows running complex analyses on huge datasets with nothing more than a web browser, and without needing to worry about details like resource allocation, and format conversions. Galaxy makes high-end computational biology more accessible, efficient, and reproducible.
Title: Patching central simple algebras and quadratic forms
Seminar: Algebra
Speaker: Daniel Krashen of University of Georgia
Contact: R. Parimala, parimala@mathcs.emory.edu
Date: 2008-09-16 at 4:00PM
Venue: MSC W303
Download Flyer
Abstract:
Recently, David Harbater and Julia Hartmann have developed a technique called ``field patching," which provides a new set of tools to study and construct algebraic objects of various types over function fields of curves defined over complete discretely valued fields. In this talk, I will describe these techniques, and give a survey of applications to central simple algebras and quadratic forms, including results on the period-index problem, the $u$-invariant, and admissibility of finite groups over these fields.
Title: Hopf's Conjecture and Aleksandrov's Theorem: Soap Bubbles Are Round Spheres (Part 2)
Seminar: Analysis and Differential Geometry
Speaker: Pascal Philipp of Emory University
Contact: Vladimir Oliker, oliker@mathcs.emory.edu
Date: 2008-09-16 at 4:00PM
Venue: MSC W301
Download Flyer
Abstract:
50 years ago Aleksandrov proved that the only embedded compact surfaces of constant mean curvature are round spheres. In this talk, we will continue the presentation of Aleksandrov's proof and some interesting geometric techniques.
Title: Computerized Voting: Will you be able to vote? Will your vote be properly counted?
Colloquium: Computer Science
Speaker: Barbara Simons of
Contact: Erin Nagle, erin@mathcs.emory.edu
Date: 2008-09-11 at 4:00PM
Venue: MSC W201
Download Flyer
Abstract:
Almost \$4 billion in federal dollars, provided by the 2002 Help America Vote Act (HAVA), resulted in the initial widespread purchase of paperless computerized voting systems (Direct Recording Electronic or DREs) by many states, including Georgia. Election officials were told that DREs would be cheaper than alternative voting systems, a claim that ignored the costs of testing and secure storage, as well as very expensive annual maintenance contracts. They were told that DREs had been extensively tested and that the certification process guaranteed that the machines were reliable and secure. They were also told that DREs would allow people with disabilities to vote independently. In some cases officials were threatened with lawsuits or actually sued by certain disability rights groups if they expressed hesitation at purchasing DREs. However, early independent security studies, followed by recent results from California’s “Top-to-Bottom Review” have revealed that the DREs that were tested by California – all of which had been federally qualified and state certified – are poorly designed, badly programmed, insecure, unreliable, and at times very difficult for people with disabilities to use. As a result the California Secretary of State Debra Bowen decertified all of the tested systems. While she recertified them, her conditional recertification orders, which contain long lists of detected problems, have still longer lists of conditions, some quite arduous, that must be met. HAVA also required each state to create a statewide computerized database of all registered voters. Congressional Democrats and Republicans supported the computerized databases, because they felt the databases would prevent widespread voter disenfranchisement or voting by illegal aliens, respectively. However, if the databases are not secure and properly monitored, it will be possible to strip large numbers of voters’ names from the databases or to pad the databases with the names of non-citizens. We shall discuss some of the voting technologies that will be used in November, as well as national efforts to make our elections more secure and accurate through the use of voter verified paper ballots. We shall also review the situation in Georgia. Because Georgia still uses paperless Diebold DREs, there will be no way to conduct an audit or recount of the November 2008 election in Georgia. Information on this speaker can be found here: http://usacm.acm.org/usacm/Committee/Simons.htm
Title: The Brauer group
Seminar: Algebra
Speaker: Eric Brussel of Emory University
Contact: Eric Brussel, brussel@mathcs.emory.edu
Date: 2008-09-09 at 4:00PM
Venue: MSC W303
Download Flyer
Abstract:
The Brauer group, comprising classes of central simple algebras over a field, plays an important role in the study of a field's arithmetic. We will give an overview of the Brauer group, and discuss how it has been used to produce some important examples in field arithmetic and algebraic geometry.
Title: Hopf's Conjecture and Aleksandrov's Theorem: Soap Bubbles Are Round Spheres (Part 1)
Seminar: Analysis and Differential Geometry
Speaker: Pascal Philipp of Emory University
Contact: Vladimir Oliker, oliker@mathcs.emory.edu
Date: 2008-09-09 at 4:00PM
Venue: MSC W301
Download Flyer
Abstract:
50 years ago Aleksandrov proved that the only embedded compact surfaces of constant mean curvature are round spheres. In this talk, Aleksandrov's proof and some interesting geometric techniques will be presented.