Seminars and Colloquia by Series

Geometric combinatorics, graphs and hypergraphs

Series
Other Talks
Time
Monday, February 25, 2013 - 11:05 for 1 hour (actually 50 minutes)
Location
Skiles 005
Speaker
Gil Kalai – Hebrew University and Yale University
In the lecture I will describe how several questions in geometric combinatorics translate into questions about graphs and hypergraphs. 1. Borsuk's problem. 2. Tverberg theorem and Tverberg's type problems. Tverberg's theorem asserts that (r-1)(d+1)+1 points in d-space can be divided into r parts whose convex hull intersect. I will discuss situations where less points admit such a partition and connections with graph theory. (For more background, look at this MO question Tverberg partitions with less than (r-1)(d+1)+1 points<http://mathoverflow.net/questions/88718/tverberg-partitions-with-less-than-r-1d11-points> ) 3. Helly type theorems and conditions on induced subgraphs and sub-hypergraphs. I will explain the origin to the following conjecture of Meshulam and me: There is an absolute upper bound for the chromatic number of graphs with no induced cycles of length divisible by 3. 4. Embedding of 2-dimensional complexes and high dimensional minors. I will discuss the following conjecture: A 2-dimensional simplicial complex with E edges and F 2-dimensional faces that can be embedded into 4-space satisfies F < 4e. (For more background see my post *F ≤ 4E*<http://gilkalai.wordpress.com/2013/02/01/f-4e/> )

Georgia Scientific Computing Symposium

Series
Other Talks
Time
Saturday, February 23, 2013 - 08:30 for 8 hours (full day)
Location
Georgia State University
Speaker
Georgia Scientific Computing Symposium – Georgia State University
The purpose of the GSC Symposium is to provide an opportunity for professors, postdocs, and graduate students in the Atlanta area to meet in an informal setting, to exchange ideas, and to highlight local scientific computing research. Certainly, the symposium is open to whole mathematics and computer sciences communities. The previous meetings were held at Emory University (2009), Georgia Institute of Technology (2010), Emory University (2011) and University of Georgia (2012). The 2013 GSC Symposium will be held at the Georgia State University campus and is organized by Alexandra Smirnova and Vladimir Bondarenko in the Department of Mathematics and Statistics, Georgia State. The following researchers have agreed to give invited plenary lectures: Hao Gao, Department of Mathematics and Computer Science, Department of Radiology and Imaging Sciences, Emory University; Guillermo Goldsztein, School of Mathematics, Georgia Institute of Technology; Yi Jiang, Department of Mathematics and Statistics, Georgia State University; Caner Kazanci, Department of Mathematics, University of Georgia; Brani Vidakovic, College of Engineering, Georgia Institute of Technology. There will be poster sessions. Anyone attending this symposium may present a poster. We especially encourage graduate students and postdocs to use this opportunity displaying their research results. Please register at the Symposium website.

Markov bases: discussion

Series
Other Talks
Time
Monday, February 18, 2013 - 17:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Pedro Rangel, Luo Ye, Robert Krone – Georgia Tech
We will discuss the details of the Markov bases chapter not covered in the previous talks.(Algebraic statistics reading seminar)

Courtesy Listing: Large-Scale Numerical Linear Algebra Techniques for Big Data Analysis

Series
Other Talks
Time
Friday, February 15, 2013 - 14:00 for 1 hour (actually 50 minutes)
Location
Klaus 2443
Speaker
Jie Chen – Argonne National Laboratory

Please Note: Hosted by the School of Computational Science and Engineering

As the term "big data'' appears more and more frequently in our daily life and research activities, it changes our knowledge of how large the scale of the data can be and challenges the application of numerical analysis for performing statistical calculations. In this talk, I will focus on two basic statistics problems sampling a multivariate normal distribution and maximum likelihood estimation and illustrate the scalability issue that dense numerical linear algebra techniques are facing. The large-scale challenge motivates us to develop scalable methods for dense matrices, commonly seen in statistical analysis. I will present several recent developments on the computations of matrix functions and on the solution of a linear system of equations, where the matrices therein are large-scale, fully dense, but structured. The driving ideas of these developments are the exploration of the structures and the use of fast matrix-vector multiplications to reduce the general quadratic cost in storage and cubic cost in computation. "Big data'' offers a fresh opportunity for numerical analysts to develop algorithms with a central goal of scalability in mind. It also brings in a new stream of requests to high performance computing for highly parallel codes accompanied with the development of numerical algorithms. Scalable and parallelizable methods are key for convincing statisticians and practitioners to apply the powerful statistical theories on large-scale data that they currently feel uncomfortable to handle.

Atlanta Lecture Series in Combinatorics and Graph Theory VIII

Series
Other Talks
Time
Saturday, February 9, 2013 - 09:00 for 1 hour (actually 50 minutes)
Location
Georgia State University
Speaker
Van Vu – Yale University
Emory University, the Georgia Institute of Technology and Georgia State University, with support from the National Security Agency and the National Science Foundation, are hosting a series of mini-conferences. The eighth in the series will be held at Georgia State University on February 9 -10, 2013. This mini-conference's featured speaker is Dr. Van Vu, who will give two one-hour lectures. There will be five one-hour talks and a number of half-hour talks given by other invited speakers. For more info, check titles, abstracts, and schedule.

Courtesy Listing: Modeling the toughness of metallic glasses

Series
Other Talks
Time
Friday, February 8, 2013 - 14:00 for 1 hour (actually 50 minutes)
Location
Klaus 2443
Speaker
Chris Rycroft – UC Berkeley and LBNL

Please Note: School of Computational Science and Engineering job candidate talk

Metallic glasses are a new type of alloy whose atoms have an amorphous arrangement in contrast to most metals. They have many favorable properties such as excellent wear resistance and high tensile strength, but are prone to breakage in some circumstances, depending on their method of preparation. The talk will describe the development of a quasi-static projection method within an Eulerian finite-difference framework, for simulating a new physical model of a metallic glass. The simulations are capable of resolving the multiple timescales that are involved, and provide an explanation of the experimentally observed differences in breakage strength, which may aid in the use of these materials in practical applications. The same Eulerian simulation framework can be adapted to address a variety of other problems, such as fluid-structure interaction, and the mechanical modeling of multicellular clusters.

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