All Seminars
| Title: Motives of quadrics II |
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| Seminar: Algebra |
| Speaker: V. Suresh of Emory University and University of Hyderabad |
| Contact: R. Parimala, parimala@mathcs.emory.edu |
| Date: 2009-09-29 at 4:00PM |
| Venue: MSC W303 |
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| Abstract: |
| Title: Polynomials non-negative on non-compact semialgebraic sets |
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| Seminar: Algebra |
| Speaker: Ha Nguyen of Emory University |
| Contact: Vicki Powers, vicki@mathcs.emory.edu |
| Date: 2009-09-28 at 4:00PM |
| Venue: MSC W303 |
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| Abstract: Recently, M. Marshall answered a long-standing question in real algebraic geometry by showing that if $f(x,y) \in \mathbf{R}[x,y]$ and $f(x,y) \geq 0$ on the strip $[0,1] \times \mathbf{R}$, then $f$ has a representation $f = \sigma_0 + \sigma_1 x(1 - x)$, where $\sigma_0, \sigma_1 \in \mathbf{R}[x,y]$ are sums of squares. In this talk, we give the background to this result, which goes back to Hilbert's 17th problem, and our generalizations to other non-compact basic closed semialgebraic sets of $\mathbf{R}^2$ which are contained in strip. We also give some negative results. |
| Title: Record Linkage: Concepts and Practice with FRIL |
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| Seminar: Computer Science |
| Speaker: Pawel Jurczyk of Emory University |
| Contact: James Lu, jlu@mathcs.emory.edu |
| Date: 2009-09-25 at 3:00PM |
| Venue: MSC W301 |
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| Abstract: Record Linkage is the task of finding entries that refer to the same entity in two or more data sets. It is useful for joining and cleaning data sets that do not have unique common keys, and is important in many studies in business, public health, sociology and psychology, where reconciling independently collected data sets is often the most important and time-consuming first step. In this talk, we describe the basic concepts of automated record linkage and demonstrate FRIL, an open-source software collaboratively developed at Emory and the CDC that facilitates fast and accurate linkages. FRIL implements an array of standard record matching algorithms as well as a large number of user tunable parameters for improving efficiency and precision. It provides a friendly, easy to use interface and a set of useful visualization tools for quick user feedbacks. Since its release in 2008, FRIL has been widely adopted, including uses by research groups at the National Center on Addiction and Substance Abuse, the Harvard Business School and the NIH. This talk should be of interest to faculty and graduate students whose research involve data collection, integration, and cleansing. Pawel Jurczyk is a Ph.D. Candidate in the Computer Science and Informatics Program at Emory University. His interest includes distributed computing, distributed database query processing, and data/information privacy. He has been an ORISE fellow at the CDC since 2007, and has taught courses in Introduction to Computer Science and Databases. |
| Title: Partitions of the Subset Lattice into Intervals |
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| Seminar: Combinatorics |
| Speaker: William T. Trotter of School of Mathematics, Georgia Tech |
| Contact: Dwight Duffus, dwight@mathcs.emory.edu |
| Date: 2009-09-25 at 4:00PM |
| Venue: W306 |
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| Abstract: |
| Title: Motives of quadrics, I |
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| Seminar: Algebra |
| Speaker: V. Suresh of University of Hyderabad and Emory University |
| Contact: Parimala, parimala@mathcs.emory.edu |
| Date: 2009-09-22 at 4:00PM |
| Venue: MSC W303 |
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| Abstract: |
| Title: Counting Resonances in Hyperbolic Space |
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| Seminar: Analysis and Differential Geometry |
| Speaker: David Borthwick of Emory University |
| Contact: David Borthwick, davidb@mathcs.emory.edu |
| Date: 2009-09-22 at 4:00PM |
| Venue: MSC W301 |
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| Abstract: I'll introduce some basic techniques for estimating determinants of operators. Then I'll show how these techniques are applicable to the problem of counting resonances for perturbations of the hyperbolic plane. |
| Title: Independent dominating sets in graphs of girth five |
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| Seminar: Combinatorics |
| Speaker: Paul Horn of Emory University |
| Contact: Dwight Duffus, dwight@mathcs.emory.edu |
| Date: 2009-09-18 at 4:00PM |
| Venue: W306 |
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| Abstract: One of the earliest results using the probabilistic method, due independently to Lovasz, Payan and Arnautov, shows that every d-regular, n-vertex graph has a dominating set of size at most (n(1 + log(d+1)))/(d+1). In this talk, we show that if the graph has girth five, one can actually find an independent dominating set of roughly the same size, (n log(d))/d + O(n/d). This extends results of Duckworth and Wormald who studied the problem on random regular graphs, and up to the implied constant is sharp. We further construct examples showing that for irregular graphs the corresponding statement with d replaced by the minimum degree does not hold. |
| Title: Never Give a Non-mathematician an Even Break |
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| EUMMA Meeting: N/A |
| Speaker: Prof. Ronald Gould of Emory University |
| Contact: James Herring, jlherri@emory.edu |
| Date: 2009-09-15 at 7:00PM |
| Venue: MSC W201 |
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| Abstract: Come and attend EUMMA's first event of the year as we learn how a little mathematics can go a long way in card games, coin flipping games, and even paintball. All those with any interest in mathematics and computer science are encouraged to attend. |
| Title: The Cahn-Hilliard Equation: Coarsening and Steady States |
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| Colloquium: Analysis and Differential Geometry |
| Speaker: Professor Amy Novick-Cohen of Technion-Israel Institute of Technology |
| Contact: Vladimir Oliker, oliker@mathcs.emory.edu |
| Date: 2009-09-08 at 4:00PM |
| Venue: MSC W301 |
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| Abstract: The Cahn-Hilliard equation constitutes a phenomenological model for phase separation in binary alloys which was proposed some 50 years ago. Initially it was thought that a complete understanding of the steady states would yield a firm understanding of the implications of the equation for phase transition. While a complete delineation of the steady states is possible at least in one dimension, a good understanding of the various stages of the dynamics such as coarsening, or the growth of the dominant length scale of the system, comes primarily via other paths. |
| Title: Mod 4 invariants of line-bundle-valued quadratic forms |
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| Seminar: Algebra |
| Speaker: Asher Auel of Emory |
| Contact: Skip Garibaldi, skip@mathcs.emory.edu |
| Date: 2009-09-08 at 4:00PM |
| Venue: MSC W303 |
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| Abstract: Alongside rapid advances in algebraic geometry, algebraic topology, and K-theory, the 1970s saw the initiation of the study of quadratic forms over general algebraic varieties and the emergence of the theory of line bundle-valued quadratic forms. The theory of invariants of such forms remains quite a mystery. In this talk, I'll give an introduction to line bundle-valued forms, similarity transformations, and classical cohomological invariants of quadratic forms. I'll present a new etale cohomological invariant for line bundle-valued forms that generalizes the Clifford invariant. This invariant is related to a four-fold cover of the orthogonal similitude group. |