All Seminars
| 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. |
| Title: Systems and Software Engineering at Siemens Corporate Research |
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| Colloquium: Computer Science |
| Speaker: Brian Berenbach of Siemens Corporate Research, Princeton |
| Contact: James J. Lu, jlu@mathcs.emory.edu |
| Date: 2009-09-04 at 3:00PM |
| Venue: MSC W301 |
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| Abstract: In a corporate research environment there is always a tension between providing services to the Siemens business units, and performing short and long term research. The systems and software engineering department at SCR in Princeton performs applied research while providing both technical and management consulting services to Siemens business units and government agencies. When performing research, Siemens often partners with university colleagues from many different countries. Much of the research and work is challenging and interdisciplinary, cutting across sales, marketing, engineering and application domains.\\ \\ This talk will describe some of the challenges faced in executing very large projects, typically with a mix of hardware and software, while conducting research to improve engineering processes and support tools. Ongoing research in systems and software engineering will be described in the context of very large projects SCR has and is continuing to support, in such domains as rail transit, postal systems, integrated health care networks, automotive systems and medical products.\\ \\ Bio:\\ \\ Brian Berenbach is a senior member of the technical staff at Siemens Corporate Research in Princeton. He is an ACM Distinguished Engineer and has published extensively on software and requirements engineering. His textbook Software Systems Requirements Engineering: In Practice was recently published by McGraw-Hill. Mr. Berenbach received his M.Sc. from Emory in 1967.\\ |
| Title: Counting Substructures |
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| Seminar: Combinatorics |
| Speaker: Dhruv Mubayi of The University of Illinois, Chicago |
| Contact: Dwight Duffus, dwight@mathcs.emory.edu |
| Date: 2009-09-04 at 4:00PM |
| Venue: W306 |
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| Abstract: For various (hyper)graphs F, we give sharp lower bounds on the number of copies of F in a (hyper)graph with a prescribed number of vertices and edges. Our results extend those of Rademacher, Erdos and Lovasz-Simonovits for graphs and of Bollobas, Frankl, Furedi, Keevash, Pikhurko, Simonovits and Sudakov for hypergraphs. The proofs use the hypergraph removal lemma and stability results for the corresponding Turan problem proved by the above authors. |
| Title: Bertrand's postulate and subgroup growth |
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| Seminar: Algebra |
| Speaker: Ben McReynolds of University of Chicago |
| Contact: Skip Garibaldi, skip@mathcs.emory.edu |
| Date: 2009-09-01 at 4:00PM |
| Venue: MSC W303 |
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| Abstract: In this talk, I will discuss an extension of Bertrand's postulate on gaps between primes to finitely generated linear group that provides an interesting variant of subgroup growth. This is also connected with the residual average of a residually finite group, a variant which quantifies residual finiteness. This talk will largely be accessible to a general audience. |
| Title: Model to Predict I/O For SPARQL Queries Using the TripleT Index |
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| Master's Thesis Defense: Computer Science |
| Speaker: Kanwei Li of Emory University |
| Contact: Kanwei Li, kli@gmail.com |
| Date: 2009-07-29 at 4:00PM |
| Venue: MSC E408 |
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| Abstract: |
| Title: Hamiltonicity and Pancyclicity of 4-connected, Claw- and Net-free Graphs |
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| Defense: Dissertation |
| Speaker: Silke Gehrke of Emory University |
| Contact: Silke Gehrke, sgehrke@emory.edu |
| Date: 2009-05-29 at 4:00PM |
| Venue: MSC W301 |
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| Abstract: A well-known conjecture by Manton Matthews and David Sumner states, that every $4$-connected $K_{1,3}$ -free graph is hamiltonian. The conjecture itself is still wide open, but several special cases have been shown so far. We will show, that if a graph is $4$-connected and $\{K_{1,3}$, $N\}$- free, where $N =$ $N(i, j, k)$, with $i + j + k = 5$ and $i$, $j$, $k \geq 0$, the graph is pancyclic. |
| Title: Nearly Perfect Packings |
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| Defense: Dissertation |
| Speaker: Daniel Martin of Emory University |
| Contact: Daniel Martin, dmarti8@emory.edu |
| Date: 2009-05-12 at 2:00PM |
| Venue: MSC W301 |
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| Abstract: |