All Seminars

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Title: A Mathematician's Guide to Working with Engineers
Seminar: Numerical Analysis and Scientific Computing
Speaker: Steven Hamilton of Oak Ridge National Laboratory
Contact: James Nagy, nagy@mathcs.emory.edu
Date: 2016-02-19 at 1:00PM
Venue: W306
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Abstract:
Problems in computational science often require interdisciplinary collaboration. Differences in the vocabulary, skills, and expectations of different fields can make these collaboration efforts extremely challenging. In this talk, I will discuss strategies for working on interdisciplinary teams that can contribute to the success (or failure) of a project. In particular, I will discuss some common pitfalls that I have seen mathematicians fall into when working with engineers and domain scientists.
Title: A Mathematician's Guide to Working with Engineers
Seminar: Numerical Analysis and Scientific Computing
Speaker: James Nagy of Emory University
Contact: James Nagy, nagy@mathcs.emory.edu
Date: 2016-02-17 at 1:00PM
Venue: W306
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Abstract:
Problems in computational science often require interdisciplinary collaboration. Differences in the vocabulary, skills, and expectations of different fields can make these collaboration efforts extremely challenging. In this talk, I will discuss strategies for working on interdisciplinary teams that can contribute to the success (or failure) of a project. In particular, I will discuss some common pitfalls that I have seen mathematicians fall into when working with engineers and domain scientists.
Title: A Mathematician's Guide to Working with Engineers
Seminar: Numerical Analysis and Scientific Computing
Speaker: James Nagy of Emory University
Contact: James Nagy, nagy@mathcs.emory.edu
Date: 2016-02-17 at 1:00PM
Venue: W306
Download Flyer
Abstract:
Problems in computational science often require interdisciplinary collaboration. Differences in the vocabulary, skills, and expectations of different fields can make these collaboration efforts extremely challenging. In this talk, I will discuss strategies for working on interdisciplinary teams that can contribute to the success (or failure) of a project. In particular, I will discuss some common pitfalls that I have seen mathematicians fall into when working with engineers and domain scientists.
Title: Hodge Theory on Matroids
Seminar: Algebra
Speaker: Eric Katz of University of Waterloo
Contact: David Zureick-Brown, dab@mathcs.emory.edu
Date: 2016-02-16 at 4:00PM
Venue: W304
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Abstract:
The chromatic polynomial of a graph counts its proper colourings. This polynomial's coefficients were conjectured to form a unimodal sequence by Read in 1968. This conjecture was extended by Rota in his 1970 address to assert the log-concavity of the characteristic polynomial of matroids which are the common generalizations of graphs and linear subspaces. We discuss the resolution of this conjecture which is joint work with Karim Adiprasito and June Huh. The solution draws on ideas from the theory of algebraic varieties, specifically Hodge theory, showing how a question about graph theory leads to a solution involving Grothendieck's standard conjectures.
Title: Finding the hidden symmetries of Nature
Seminar: Mathematical Physics
Speaker: Maria Clara Nucci of University of Perugia
Contact: Michele Benzi, benzi@mathcs.emory.edu
Date: 2016-02-10 at 4:00PM
Venue: W303
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Abstract:
Twenty years ago David J. Gross presented, at the National Academy of Sciences, a paper entitled "The role of symmetry in fundamental physics", which was later published in PNAS. I shall use that talk as a thread in order to illustrate my recent work related to the following main themes: (A) going from Classical to Quantum Mechanics by preserving Noether symmetries; (B) finding hidden linearity of maximally superintegrable systems; (C) determining Lagrangians (and Noether symmetries) for systems without Lagrangians. I shall provide several examples for each theme, including models in population dynamics and the Lorenz system in meteorology
Title: The Iwasawa main conjecture for elliptic curves at supersingular prime
Seminar: Algebra
Speaker: Florian Sprung of Princeton/IAS
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2016-02-09 at 4:00PM
Venue: W304
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Abstract:
Iwasawa theory is a bridge between analytic objects and algebraic objects. We give a friendly introduction to the main conjecture in the ordinary case (and define what 'ordinary' means), and then outline the supersingular (=non-ordinary) theory. The main philosophy of the proof in the supersingular case is to work with a pair of simple objects similar to the ordinary ones.
Title: Numerical techniques for multiscale dynamical systems
Seminar: Numerical Analysis and Scientific Computing
Speaker: Seong Jun Kim of Georgia Institute of Technology
Contact: Lars Ruthotto, lruthotto@emory.edu
Date: 2016-02-05 at 1:00PM
Venue: W306
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Abstract:
The main aim of this talk is to discuss multiscale algorithms for a class of highly oscillatory dynamical systems. There had been many algorithms for computing the macroscale behavior of highly oscillatory dynamical systems with the help of microscale systems. While they achieved remarkable successes, their applications to general highly oscillatory dynamical systems are still limited. This talk will provide some of the background materials, perspectives on the current challenges as well as recent progresses with my collaborators.
Title: Chow groups with coefficients and generalized Severi-Brauer varieties
Seminar: Algebra
Speaker: Patrick McFaddin of University of Georgia
Contact: David Zureick-Brown, dzb@mathcs.emory.edu
Date: 2016-02-02 at 4:00PM
Venue: W304
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Abstract:
The theory of algebraic cycles on homogenous varieties has seen many useful applications to the study of central simple algebras, quadratic forms, and Galois cohomology. Significant results include the Merkurjev-Suslin Theorem and Suslin's Conjecture, recently proved by Merkurjev. Despite these successes, a general description of Chow groups and Chow groups with coefficients remains elusive, and computations of these groups are done in various cases. In this talk, I will give some background on K-cohomology groups of Severi-Brauer varieties and discuss some recent work on computing these groups for an algebra of index 4.
Title: Indexing Moving Objects for Predictive Spatio-Temporal Queries
Defense: Dissertation
Speaker: Xiaofeng Xu of Emory University
Contact: Xiaofeng Xu, xiaofeng.xu@emory.edu
Date: 2016-01-28 at 2:30PM
Venue: W304
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Abstract:
The rapid development of positioning techniques has enabled information to be widely collected on continuously moving objects, such as vehicles and mobile device users. Since moving object data is large and updates frequently, database systems supporting massive updates and predictive spatio-temporal queries are essential for modern location-based services. Traditional spatial accessing or indexing mechanisms barely consider velocity information of the objects to improve query performance. In this dissertation, I present novel approaches that augment existing tree-based and grid-based indexes for moving object databases with velocity information and prove that these approaches can significantly improve query performance with comparable update performance in both in-disk and in-memory scenarios.. Predictive range query, which retrieves objects in a certain spatial region at some future time, is the most motivating type of spatio-temporal queries in real world location-based services. Different from predicting future location of a single moving object, performing predictive range queries over large moving object databases incurs much heavier computational burden, which makes efficiency as important as accuracy for real-time spatio-temporal enquiries. Motion functions, which predict future object locations based on some analytic functions, can efficiently process short-term predictive range queries, since they can be seamlessly embedded into existing indexing mechanisms. However, motion functions cannot perform long-term predictions since motions of the moving objects might change over time. Other prediction functions such as trajectory patterns and statistical graphic models are more accurate but less efficient. In this dissertation, I also present a pruning mechanism that improve the performance for long-term predictive range queries based on (high-order) Markov chain models learned from historical trajectories. The key to our approach is to devise compressed representations for sparse multi-dimensional matrices, and leverage efficient algorithms for matrix computations. We conduct experiments on both simulated and real world datasets to demonstrate that our methods gain significant improvements over other existing methods.
Title: Vector bundles on moduli space of stable curves with marked points.
Seminar: Algebra
Speaker: Anna Kazanova of University of Georgia
Contact: David Zureick-Brown, dab@mathcs.emory.edu
Date: 2016-01-26 at 4:00PM
Venue: W304
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Abstract:
Conformal block vector bundles are vector bundles on the moduli space of stable curves with marked points defined using certain Lie theoretic data. Over smooth curves, these vector bundles can be identified with generalized theta functions. In this talk we discuss extension of this identification over the stable curves. This talk is based on joint work with P. Belkale and A. Gibney.