Colloquiums 2008- 2009
Please see the Calendar of Events for more information
DATE: Friday, April 10, 2009
TIME: : 2:30 pm.
LOCATION: Paul Erdos Room, 796 COE
Speaker: Denish Shah, Ph.D. Assistant Professor of Marketing, Assistant Director - Center for Excellence in Brand & Customer Management, J. Mack Robinson College of Business, Georgia State University.
Title: "Expanding the Role of Marketing: From Customer Equity to Market Capitalization ?"
Abstract:
Can the marketer drive the stock price of the firm? Yes, it should be possible. Towards this endeavor, the authors develop a framework to link customer equity (as determined by the customer lifetime value metric) to market capitalization (as determined by the stock price of the firm). The authors test the framework through an empirical field experiment with two Fortune 1000 firms in the business-to-business and business-to-consumer context, respectively. The findings show that: (i) A customer equity - based framework can reliably predict the market capitalization of the firm, and (ii) Marketing strategies directed at increasing the customer equity not only increase the stock price of the firm, but also beat market expectations. Furthermore, the results indicate that the relationship between customer equity and market capitalization is moderated by risk factors in the form of volatility and vulnerability of cash flows from customers. By accounting for these factors, the association between customer equity and market capitalization is improved. The findings serve to broaden the scope and role of marketing while reinforcing the importance of the marketer to any organization.
Hosts: Yixin Fang and Jiawei Liu
DATE: Friday, February 27, 2009
TIME: : 2:30 pm.
LOCATION: Paul Erdos Room, 796 COE
Speaker: Craig Huneke, The Henry J. Bischoff Professor of Mathematics at the University of Kansas
Title: "How many times does a polynomial vanish along an algebraic subset of points?"
Abstract: This talk will discuss the title question. It is not too hard to figure out what it should mean for a polynomial f(X_1,...,X_n) to have an k-fold zero at a point (a_1,a_2,...,a_n) in complex n-space. One demands that f and all its partial derivatives up to k-1 st order vanish at that point. But there are several possibilities if one asks that f vanish along an algebraic subset X of complex n-space. (An algebraic set is the set of zeroes of some set of polynomials.) The differences between possible definitions leads to what are called symbolic powers of ideals. Many open questions pertain to symbolic powers. We will discuss some elementary ones.
Hosts: Florian Enescu and Yongwei Yao
DATE: Friday, February 20, 2009
TIME: : 2:00 pm--3:00pm.
LOCATION: Paul Erdos Room, 796 COE
Speaker: Jean M-S Lubuma (University of Pretoria, South Africa)
Title: "Non-standard finite difference schemes for impact oscillators with one degree or two degree of freedom"
Host: Dr. Hattingh
DATE: Friday, November 21, 2008
TIME: : 2:00 pm--3:00pm.
LOCATION: Paul Erdos Room, 796 COE
Speaker: Qi Long, Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University
Title: "A Double Robust Nearest Neighbor-Based Multiple Imputation Approach"
Abstract: In this talk, a nearest neighbor-based multiple imputation approach is proposed to recover information for missing observations. Under missing at random (MAR) mechanism, the proposed imputation approach has a double robustness property. Specifically, this imputation approach is robust to misspecification of either one of the two working models that are used to define imputing sets for missing observations. Asymptotic distributions for our proposed estimators are derived. Our simulation results show that the proposed approach is competitive or outperforms existing methods in a wide range of settings. The proposed imputation approach is illustrated using data from a colorectal adenoma study.
Host: Yichuan Zhao
DATE: Friday, November 7, 2008
TIME: : 2:00 pm--3:00pm.
LOCATION: Paul Erdos Room, 796 COE
Speaker: Lance A. Waller, Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University
Title: "Spatial Statistics in Disease Ecology: Patterns and Processes in Landscape Epidemiology"
Abstract: Inferring process from pattern is a long-standing goal in landscape ecology and epidemiology, but is limited by data availability and parameter identifiability. We will review a broad conceptual framework for the analysis of data associated with the spread of disease in time and space, illustrating a continuum of perspectives ranging from ecology to public health surveillance and identify areas needing further development. Using this framework, we explore expanded roles for statistical techniques in mathematical models of the spread of raccoon rabies in the northeastern United States, focusing on assessments of fit for mathematical models of disease dynamics and exploration of the phylogeography of pathogens in wildlife populations.
Host: Yichuan Zhao.
DATE: Friday, April 25, 2008
TIME: : 2:30 pm--3:30pm.
LOCATION: Paul Erdos Room, 796 COE
Speaker: Ian M. Aberbach, University of Missouri Columbia
Title: "Uniform bounds in Noetherian rings"
Abstract: Let R be a commutative ring (with unit). Then R is Noetherian if every ideal of R is finitely generated. In the words of Craig Huneke, "behind the obvious finiteness condition in Noetherian rings, . . ., there lie many deeper and hidden types of finiteness which come to light in terms of uniform behavior. . . . [by that] we mean statements which give some bounds (usually numerical) not just for one ideal, but for all ideals simultaneously." The talk will try to give a flavor of such results, touching on, for instance, uniform Artin-Rees theorems, uniform annihilation of local cohomology and the connection to uniform annihilators of homology in classes of free complexes, tight closure and its uniform annihilation (i.e., test elements), Briancon-Skoda type theorems, and uniform degrees of nilpotency for parameter ideals.
Prof. Aberbach is the main speaker of GSU-USC Commutative Algebra meeting in Atlanta April 25-April 27.
Hosts: Florian Enescu and Yongwei Yao.
DATE: Friday, April 18, 2008
TIME: : 2:00 pm--3:00pm.
LOCATION: Paul Erdos Room, 796 COE
Speaker:Mourad Tighiouart, Co-Director of the Winship Cancer Institute Department of Biostatistics at Emory University
Title: "Design Considerations in Cancer Phase I clinical Trials: Escalation with Overdose Control"
We describe a Bayesian adaptive design for cancer phase I clinical trials. The method makes use of all the information available at the time of each dose assignment, and directly addresses the ethical need to control the probability of overdosing. The design is Bayesian-feasible and the sequence of doses generated by this scheme is consistent. Performance of this design under a large class of prior distributions will be explored through simulations. In particular, joint prior distributions for the maximum tolerated dose (MTD) and probability of dose limiting toxicity (DLT) at the initial dose with negative a priori correlation structure are used to model the dose-response relationship. When patients' specific characteristics thought to be related to treatment susceptibility are available at the onset of the trial, we show how this adaptive design takes into account this information. The performance of this extended design is evaluated by comparing the following designs via extensive simulations: (1) Design using a covariate; patients are accrued to the trial sequentially and the dose given to a patient depends on his/her covariate value, (2) Design ignoring the covariate; patients are accrued to the trial sequentially and the dose given to a patient does not depend on his/her covariate value, and (3) Design using separate trials; In each group, patients are accrued to the trial sequentially and EWOC is implemented in each group. The above methodologies are illustrated with examples of phase I trials conducted at Fox Chase Cancer Center and Winship Cancer Institute.
Host: Dr. Yichuan Zhao
DATE:
Wednesday, January 16, 2008
TIME: 2:15 PM, Refreshments at 2 PM
LOCATION: Paul Erdos Room,
796 COE
Speaker: Tom Bella, University of Connecticut
Title: "Quasiseparable matrices and polynomials"
Abstract: The interplay between polynomials and dense structured matrices is a classical topic. Structure in this sense is interpreted to mean their $n 2 $ entries can be ``compressed'' to a smaller number ${\mathcal O}(n)$ of parameters. Operating directly on these parameters allows one to design efficient {\em fast algorithms} for these matrices and for the related applied problems. In the past decades matrices with structures such as DFT/DCT/DST, Toeplitz, Hankel, Vandermonde or Cauchy structure were the focus of attention. In this talk, some results that demonstrate that a relatively new {\em quasiseparable} structure enables substantial generalizations of a number of different algorithms will be presented.
Host: Mihaly Bakonyi
DATE: Friday, November 16, 2007
TIME: 2:00 PM - 3:00 PM
LOCATION: Paul Erdos Room
Speaker: Vladimir Koltchinskii, School of Mathematics Georgia Institute of Technology
Title: "Sparse Recovery in Function Estimation"
Abstract: A problem of learning of a target function based on its noisy observations at random points via penalized empirical risk minimization with convex loss function and convex complexity penalty will be discussed. This includes a number of regression and large margin classification problems. It is assumed that the target function belongs to the linear span of a very large dictionary of given functions and that it has a "sparse representation" in the "dictionary". The goal is to recover the function with an error that depends mainly on the "sparsity" of the problem (even if the size of the "dictionary" is very large). An approach based on $\ell_1$-type complexity penalization will be discussed. We prove several probabilistic bounds showing the relationship between the sparsity of the empirical solution and the sparsity of the target function and provide oracle inequalities on the excess risk and the L_2-error that depend on the sparsity of the problem.
Host: Yichuan Zhao
DATE: Tuesday, November 13, 2007
TIME: 3:00 PM - 4:00 PM
LOCATION: Paul Erdos Room
Speaker: Xingxing Yu, School of Mathematics, Georgia Insitute of Technology
Title: " Judicious partitions of graphs"
Abstract: Judicious partition problems ask for partitions of the vertex set of a graph so that several quantities are optimized simultaneously. I will discuss several judicious partition problems of Bollob\'{a}s and Scott, and present our recent results on these problems (joint work with Baogang Xu).
DATE: Friday, October 26, 2007
TIME: 2:00 PM - 3:00 PM
LOCATION: Paul Erdos Room
Speaker: Charles Wells, Case Western University and Oberlin College
Title: "Category Theory and Mathematical Discourse"
Abstract: Category theory provides a new way of thinking and talking about mathematical structures. Some categorical concepts will be introduced that exhibit this new point of view. Much goes on in mathematical discourse that mathematicians may not be aware of. The discourse the author uses to introduce the categorical ideas will be used to provide examples of some of the subtleties of math discourse. The two topics of the talk are related: Category theory clarifies some of the difficulties involved in communicating math.
Host: Mariana Montiel
Joint GSU Mathematics/GA Tech colloquium
DATE: Wednesday, April 18, 2007
TIME: 4:30 PM
LOCATION: Skiles 255, Skiles Classroom Building, School of Mathematics, GaTech
Speaker: Leonid Shilnikov (Institute for Applied Mathematics & Cybernetics, Russia)
Title: "Quasihyperbolicity and strange attractors"
Abstract: We propose an effective criterion of dynamical chaos that is based on a quasihyperbolicity condition. The latter means the phase space of the system has an absorbing domain with such unstable trajectory behavior that lets us find a factor-system expanding volumes. We will give examples of quasihyperbolic attractors of both structurally stable, like Smale-William solenoids, and unstable types such as Lorenz and spiral ones. We single out a class of quasihyperbolic systems with a single saddle equilibrium state having a 1D unstable manifold. The periodic perturbations on an attractor of Lorenz type are also discussed.
Hosts: Igor Belykh and Shui-Nee Chow (GaTech)
DATE: March 30, 2007
TIME: 2:00-3:00 PM
LOCATION: COE 796
Speaker: Graham Leuskchke (Syracuse University)
Title: "Factoring the Adjoint and Maximal Cohen-Macaulay Modules"