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2016–17 Colloquium Series

This Colloquium Series is sponsored by the Math and Computer Science Department. Unless otherwise noted, all talks take place in Jepson Hall Room 109 at 4:00 p.m

Starting at 3:30 p.m. light refreshments will be served in the lounge outside of Jepson 212 — please join us.

Talks will be added as they are scheduled; please check back often.

Up Next

April 17 & 19: Senior Honors Theses Presentations

April 17 * 4:30 PM * Jepson Hall 120

 David Clayton, Almost Difference Sets, Supervised by Dr. James Davis

 Gi Heung “Robin” Kim, Differential Privacy for Growing Databases,  Supervised by Dr. Sara Krehbiel

April 19 * 4:30 PM * Jepson Hall 120

Greg Hamilton, Quantum Groups and Knot Invariants, Supervised by Dr. Heather Russell

Anh Tran, Toward a Scientific Investigation of Convolutional Neural Networks, Supervised by Dr. Arthur Charlesworth

Fiona Lynch, Differential Equations Models of Single- and Multi-Organ Tissue Damage, Supervised by Dr. Lester Caudill

Past Events

April 10 Sommer Gentry, Professor of Mathematics, United States Naval Academy. 

Talk title: Faster, Safer, Healthier: Adventures in Operations Research

Abstract: "While mathematical advances of all sorts have impacted our world for the better, operations research is a branch of mathematics that is expressly focused on applying advanced analytical methods to help make better decisions.  Operations researchers have eased traffic jams by closing selected streets, and gotten packages to you more quickly by planning U.P.S. routes with fewer left turns.  Operations researchers have shown which personal decisions are the leading causes of death, and planned maintenance schedules to minimize bridge collapses.  The mathematical tools of operations research, like using random numbers to simulate a range of outcomes when some data are unknown, or finding clever algorithms that shortcut the need to try every possible decision in order to find the best one, can be recycled to solve problems everywhere in our world. These days, I am using O.R. to increase the supply of kidneys available for patients who need a transplant and to make organ allocation more equitable to patients across the U.S.  In this talk, I will describe some of my O.R. forays into far-flung fields, and tell my favorite stories about O.R."

Bio: Sommer Gentry is Professor of Mathematics at the United States Naval Academy, and is also on the faculty of the Johns Hopkins University School of Medicine. She is a senior investigator with the Scientific Registry for Transplant Recipients. She has a B.S. in Mathematical and Computational Science and an M.S. in Operations Research, both from Stanford University, and a Ph.D. in Electrical Engineering and Computer Science from MIT. She designed matching optimization methods used for nationwide kidney paired donation registries in both the United States and Canada, and is now redistricting liver sharing boundaries to help the Organ Procurement and Transplantation Network reduce geographic disparities in transplantation. Her work has attracted the attention of major media outlets including Time Magazine, Reader’s Digest, Science, the Discovery Channel, and National Public Radio.  Gentry received the MAA’s Henry L. Alder award for distinguished teaching by a beginning mathematics faculty member, and was a finalist for the Daniel H. Wagner prize for Excellence in Operations Research Practice.

March 27 Barry Lawson, Professor of Computer Science, and Malcolm Hill, Professor of Biology, University of Richmond

Title: An Agent-Based Simulation Model of Sponge:Algae Symbiotic Relationships   Why is this important?

Abstract: One of the most important ecological interactions that occurs in shallow tropical habitats worldwide involves intracellular symbiotic interactions between dinoflagellate algae and a variety of invertebrate and protistan hosts, such as sponges and coral. The algal symbionts, known as Symbiodinium, reside within the host cells, and have long been recognized to be of vital energetic importance to the host.  Unfortunately, the dynamics of the associations (e.g., symbiont population growth behavior, loss of symbionts from the host, competition among different symbiont types, host responses to symbionts of different quality) are poorly understood.  This talk discusses ongoing interdisciplinary research at the University of Richmond, presenting motivation for, and results from, an agent-based simulation model for investigating the symbiotic relationship between algal symbionts and host sponges.  Our results suggest important future research directions, coordinating model extensions with experiments to be performed in tropical habitat field work.

March 22 at 430 PM in Jepson Hall 103 Sarah Krehbiel, Assistant Professor of Computer Science, University of Richmond

Title: Privacy and Randomness: Defense Against the Dark Arts

Course Description: The course will explore computational attacks on data privacy and fundamental algorithmic techniques for preempting them. We will consider privacy issues in a range of computational tasks, including producing summary statistics for databases, training artificial neural networks for deep learning, and secure communication protocols. The central notion of privacy we will consider is differential privacy. Differential privacy is a rigorous standard for how to safely learn population information without compromising the privacy of individuals in the sample, and it is being used by a growing number of tech companies, including Google and Apple. We will also touch on topics in cryptography. We will cover a brief survey of probability and randomized algorithms that help us understand powerful computational tools that are resistant to privacy attacks.

March 20 Ivan Blank, Associate Professor of Mathematics, Kansas State University. Dr Blank Specializes in Free Boundary Problems, Elliptic and Parabolic Partial Differential Equations, and Applications in Composite Materials.

Title: The Obstacle Problem and Connections to Mean Value Theorems in Elliptic PDEs

Abstract:  One basic property of harmonic functions is the fact that at any point the value of the function is exactly equal to the average value of the function over a ball (or a sphere) centered at that point.  This theorem can be used to establish other basic properties of harmonic functions including the maximum principle, the Harnack inequality, and some important a priori estimates. 

Standard proofs of the mean value theorem rely on smoothness and symmetry properties of the Laplacian and therefore do not generalize nicely to non-Euclidean spaces or more general elliptic operators.  However, in his Fermi lectures on the obstacle problem in 1998, Luis Caffarelli indicated how one could use solutions of specific obstacle problems to construct an elegant proof of the mean value theorem which does not depend on either the smoothness or symmetry properties of the Laplacian.  In this talk, I will explain that proof and show how my collaborators and I have used it to generalize the mean value theorem to other settings.  In order to explain the proof, I will give a short introduction to the obstacle problem.

Jan 30: Eric Brunvand, Associate Professor, School of Computing, University of Utah. 

Title: A Tale of Two Rendering Algorithms: Ray Tracing, Rasterization, and their Supporting Hardware

Abstract: The desire for ever more complex and realistic graphics drives the computer graphics hardware industry. This interest in high-quality rendering spans the range of computer hardware from high-end gaming computers and scientific workstations to small embedded platforms such as tablets and phones. While traditional graphics rendering using a Z-buffer rasterization algorithm is well supported with commercial graphics processing units (GPUs), the desire to improve image quality encourages a new look at an alternative rendering algorithm: ray tracing. While rasterizing is used in virtually all real-time rendering applications (e.g. games that use GPUs for rendering), ray tracing software is now used in virtually all motion picture rendering because of the increased realism of the lighting in the rendered images.

Ray tracing more naturally handles a variety of optical effects that increase apparent realism in generated images, but has very different computational, I/O, memory, and power profiles than Z-buffer rasterization. As an example, traditional GPUs typically use wide Single Instruction Multiple Data (SIMD) processing to exploit the parallel behavior of Z-buffer rasterization. Ray tracing has a fundamentally different parallel character, and does not naturally map to a SIMD approach. System architectures that allow more flexibility in thread parallelism can perform much better for this type of application. In this talk I will describe and compare the rasterization algorithm that is at the core of all commercial GPUs, and the ray tracing algorithm that is not well supported on GPUs, but supports more realistic lighting in the rendered images. I will also describe the impact of using ray tracing on the design of application specific processors.

Nov. 21 Ami Radunskayavisting professor of mathematics from Pomona College, specializes in dynamics and mathematical biology.

Title: The Sound of Chaos

Abstract: We are familiar with visual representations of functions, and often associate a particular family of functions with the shape of its graph. We also use graphs to illustrate qualitative features of dynamical systems.  In the same vein, we can “listen” to a dynamical system in order to understand its structure; in fact, some features are better heard than seen. In this talk, I will demonstrate this idea by exploring the “route to chaos” via graphs and sounds. I will then explain why chaotic functions are good candidates as material for real-time, interactive performance, and then I will (hopefully) play a short piece demonstrating how this might be done.

Nov. 14 Nathan Alexander, Assistant Professor of Teacher Education, University of San Francisco.

Title: Inclusive Pedagogies in STEM+C

Abstract: This talk describes the unique challenges faced both by students and faculty with regard to inclusive teaching and learning in STEM+C (Science, Technology, Engineering, Mathematics, and Computer Science). Specifically, the speaker will engage perspectives on the interconnected nature of social categorizations and discuss research and strategies on understanding long histories of oppression, discrimination, and disadvantage. This research informs practices that are applied to collegiate STEM+C classrooms and learning environments.

At University of San Francisco, Dr. Alexander is the faculty lead at the Critical Education Content and Identity Lab (CECIL), an educational curriculum design and research laboratory for science, technology, engineering, arts and mathematics. Dr. Alexander’s teaching and research focus primarily on the relationships between mathematics, social justice and education in American contexts using historical, political, and cultural lenses.

Nov. 7 Bill Ross, Professor, Richardson Chair of Mathematics, and department chair.

Title: Matrices and the Shadows of Plato’s Cave

Abstract: In Plato’s Republic, one finds the famous Allegory of the Cave. Here Plato explains how we experience reality as shadows on a cave wall which are imperfect renditions of ideals we never really see but we know are there. In this talk, we use Plato’s Allegory to discuss how certain matrices are models (ideals) for large classes of matrices. Students have already seen certain types of model matrices, the diagonal matrices, which are the models (ideals) for the symmetric matrices. Here we expand this discussion to include other classes of matrices.

Nov. 4 Gieri Simonett, Professor of Mathematics, Vanderbilt University

Title: Moving Surfaces in Geometry and Physics

Abstract: Moving surfaces are ubiquitous in many areas of mathematics and the applied sciences. In this talk I will first introduce some well-known geometric evolution equations, and then proceed to more complicated models that describe the motion of fluids and of materials that can undergo phase transitions.

Bio: Gieri Simonett earned his PhD in Mathematics from the University of Zurich, Switzerland, in 1992. After spending three years as post-doc at UCLA, he accepted a position at Vanderbilt University, where is now a full professor Simonett is an international leader in the area of nonlinear parabolic equations and free boundary problems. He has obtained fundamental results concerning the existence, regularity, and dynamic behavior of solutions to a wide array of problems involving moving boundaries, including geometric evolution equations, phase transitions, and fluid flows. Simonett has published widely and his work has appeared in the leading journals of the field. His is the co-author of the research monograph “Moving Interfaces and Quasilinear Parabolic Evolution Equations,” published in 2016.

Oct. 24 Christian Fong, third year PhD student in the Stanford Graduate School of Business. Before Stanford, Christian earned a BSE in operations research at Princeton with minors in applied mathematics and computer science. His research focuses on the U.S. Congress, causal inference, and natural language processing. 

Title: Limited Obstruction with Monopoly Agenda Setting

Abstract: In the U.S. Senate, a single senator has the ability to delay the passage of a bill even when a large majority wants the bill to pass. The Senate has the right to make its own rules, so why doesn't the Senate change its rules to streamline the process for passing bills? We present a game theoretic model of obstruction in the Senate that shows how the ability to delay the passage of bills without actually vetoing them gives minority party legislators and moderates the ability to influence the Senate's legislative agenda. A majority of the Senate prefers the resulting agenda to the bills the Senate would pass if the right to obstruction were curtailed. In a departure from the usual conventions of game theory, we find it helpful to specify the equilibrium strategies of our game's players algorithmically.

Oct. 17 Ami Radunskayavisting professor of mathematics from Pomona College, specializes in dynamics and mathematical biology.

Title: Of Mice and Math

Abstract: The title is meant to suggest that mathematics can be a link between experimental science and practical medicine, although in reality only a few mice will actually appear in this talk. I hope to tell you a story of discovery through interdisciplinary collaboration. In particular, I will tell you about four collaborations between mathematicians and scientists at the University of Otago in Dunedin, New Zealand. These four models illustrate different modeling modalities, different mathematical techniques, and different goals.

Oct. 3 Patrick G. Traynor, R'02

Title: Who Do I Think You Are? Challenges and Opportunities in Telephony Authentication 
Abstract: Telephones remain a trusted platform for bootstrapping and conducting some of our most sensitive exchanges. From banking to taxes, wide swathes of industry and government rely on telephony as a secure fall-back when attempting to confirm the veracity of a transaction. In spite of this, authentication is poorly managed between disparate telephony systems, and in the general case it is impossible to be certain of the identity of the entity at the other end of a call. In this talk, I begin with an investigation of the ways in which phone numbers are being used as strong authenticators for Internet-based systems (e.g., Caller-ID fraud, phone verified account fraud). I then detail how much stronger end-to-end mechanisms can be developed and deployed. In so doing, we argue that we can help to overcome security problems that are the direct result of such poorly placed trust.  

Bio: Patrick Traynor is an Associate Professor in the Department of Computer and Information Science and Engineering (CISE) at the University of Florida. His research focuses on the security of mobile systems, with a concentration on telecommunications infrastructure and mobile devices. His research has uncovered critical vulnerabilities in cellular networks, made the first characterization of mobile malware in provider networks and offers a robust approach to detecting and combatting Caller-ID scams. He is also interested in Internet security and the systems challenges of applied cryptography. He received a CAREER Award from the National Science Foundation in 2010 and was named a Sloan Fellow in 2014.   Professor Traynor earned his Ph.D and M.S. in Computer Science and Engineering from the Pennsylvania State University in 2008 and 2004, respectively, and his B.S. in Computer Science from the University of Richmond in 2002. After promotion and tenure in the School of Computer Science at Georgia Tech, he joined the University of Florida in 2014 as part of the UFRising Preeminence Hiring Program. He is the co-director of the Florida Institute for Cybersecurity (FICS) and is also a co-founder of Pindrop Security. 

Oct. 5 All About Computer Science Internships. Kevin Chen, Dinc Ciftci, and Kelly Farley talk about their expereinces with summer internships in computer science.

Sept. 2: Patent awarded to Computer Science alum. Brett Csorba ’14, Information Security Software Engineer at GE, and Jake Kurzer ’10, Lead Software Engineer at Leidos, will present their patent at the next Math & Computer Science Colloquium. Their patent title is System and Method for Determining String Similarity.

Aug. 30: Student research presentations. Team mentored by Dr. Lester Caudill: Ashley Alex and Rachel Lantz. Mentored by Dr. James Davis: David Clayton. Mentored by Dr. Arthur Charlesworth: Anh Tran. Team mentored by Dr. Doug Szajda: Salar Ather, Joseph Mugisha, Rachel Culpepper, Renae Taylor, Tanner Bina, Alec Justice, & Yunwen "Nicholas" Wan. Some of the researchers can’t make it to the presentation but we wanted to list them for their work nonetheless.

Aug. 29: Student research presentations. Team mentored by Dr. Kathy Hoke and Dr. Joanna Wares: Shuyi Chen, Tatum Dam, Devika Jhunjhunwala, Sinong Li, Quinn McDonough, Harrison Wenzel, Tianyuan (Patty) Zhang, Xinyi (Julie) Zhu, Chong Hui (Devin) Chen, Camryn Travis. Team mentored by Dr. Paul Kvam: Tongyu (Stephanie) Wang and Zezhong Chen. Team mentored by Dr. Michael Kerckhove: Ying Wu, Yiwen Wang, Xiaoting (Cecelia) Sun, Joshua Hayes, Nasheya Rahman, Solomon Quinn. Some of the researchers can’t make it to the presentation but we wanted to list them for their work nonetheless.