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Colloquia

Fall 2015 Colloquia

Check back soon for more information on the computer science seminar series. Unless otherwise noted, the seminars now meet on Mondays at 3pm in Stanley Thomas 302. If you would like to receive notices about upcoming seminars, you can subscribe to the announcement listserv.

September 4

Segmentation and Classification of Trajectories

Maike Buchin Ruhr-University Bochum Germany

This event will be held on Friday, 9/4/2015, at 3:00 p.m. in Stanley Thomas, Room 302. Please note the special weekday for this event.

Abstract: Nowadays, more and more movement data is being collected, of people,animals, and vehicles. Analyzing such data requires efficient algorithms. We consider two analysis tasks on this data: segmentation and classification of trajectories. That is splitting and grouping trajectories such that they have similar movement characteristics. We present two different approaches to these problems. Criteria-based segmentations seeks to segment a trajectories such that each segment fulfills a given spatio-temporal criteria. The efficiency of algorithms for this depends on properties of the criteria. A model-based approach on the other hand assumes a movement model parameterized by a single parameter, like the Brownian bridge movement model. An optimal segmentation (resp. classification) is defined as one that minimizes an information criterion balancing the likelihood of the model and its size. We give an efficient algorithm to compute the optimal classification for a discrete set of parameter values. For continuous parameters the problem becomes NP-hard, but is polynomial time computable under mild assumptions on the input.

About the Speaker: Maike Buchin is an assistant professor of mathematics and computer science at Ruhr-Universitaet Bochum, Germany. Her research focusses on geometric algorithms in particular for the analysis of movement data. She obtained her PhD in 2007 from Freie Universitaet Berlin, Germany, and before coming to Bochum she was a postdoctoral researcher at Utrecht University and a visiting assistant professor at TU Eindhoven in the Netherlands.
September 16

From Theory to Practice: Crowdsourcing and Cost Allocation

Nicholas Mattei Optimization Research Group at NICTA / University of New South Wales

This event will be held on Wednesday, 9/16/2015, at 3:00 p.m. in Stanley Thomas, Room 302. Please note the special weekday for this event.

Abstract: Modern technology enables computers and (by proxy) humans to communicate at distances and speeds previously unimaginable, connecting large numbers of agents over time and space. These groups of agents must make collective decisions, subject to constraints and preferences, in important settings including: item selection; resource or task allocation; and cost distribution. In CS, these topics fall into algorithmic game theory (ADT), algorithmic decision theory (AGT) and computational social choice (ComSoc). Results in these areas have impact within AI, optimization, recommender systems, data mining, and machine learning. Many of the key theoretical results in these areas are grounded on worst case assumptions about agent behavior or the availability of resources. Transitioning these theoretical results into practice requires data driven analysis and experiment. We detail two projects focused on applying theoretical results to real world decision making: a novel mechanism for using crowd sourcing when selecting peers and using cooperative game theory to distribute delivery costs to clients. Both of these projects leverage data to perform detailed experiments and resulted in deployable, open source decision tools.

About the Speaker: Nicholas Mattei is a senior researcher in the Optimization Research Group at NICTA and a conjoint lecturer at the University of New South Wales in Sydney, Australia. His research focuses on computational aspects of social choice, preference aggregation, and assignment; using computation to enable and augment human decision making. Along with Prof. Toby Walsh, he is the founder and maintainer of PrefLib: A Library for Preferences. He previously worked as a programmer and embedded electronics designer for nano-satellites at NASA Ames Research Center. He received his Ph.D from the University of Kentucky under the supervision of Prof. Judy Goldsmith in 2012.
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School of Science and Engineering, 201 Lindy Boggs Center, New Orleans, LA 70118 504-865-5764 sse@tulane.edu