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Tutorial Speakers

 

Tutorial Speakers

 

Klaus-Robert Mueller

http://www.first.gmd.de/persons/Mueller.Klaus-Robert.html

Towards Brain-Computer Interfacing

 

Abstract:  Brain Computer Interfacing (BCI) aims at making use of brain signals for example the control of objects, spelling, gaming and so on.  This tutorial will first provide a brief overview of the current BCI research activities and provide details in recent developments on both invasive and non-invasive BCI systems. In a second part -- taking a physiologist’s point of view -- the necessary neurological/neurophysical background is provided and medical applications are discussed. The third part -- now from a machine learning and signal processing perspective – shows the wealth, the complexity and the difficulties of the data available, a truely enormous challenge. In real-time a multi-variate very noise contaminated data stream is to be processed and classified.

 

Finally, I report in more detail about the Berlin Brain Computer (BBCI) Interface that is based on EEG signals and take the audience all the way from the measured signal, the preprocessing and filtering, the classification to the respective application.  BCI communication is discussed in a clincial setting and for gaming (e.g. pacman).

 

Bio: Klaus-Robert Mueller received the Masters Degree in Mathematical Physics 1989 and the PhD in theoretical computer science in 1992, both from University of Karlsruhe, Germany. From 1992 to 1994 he worked as a Postdoctoral fellow at GMD FIRST, in Berlin where he started to built up the Intelligent Data Analysis (IDA) Group. From 1994 to 1995 he was a European Community STP Research Fellow at University of Tokyo in Prof.~Amari's Lab.  From 1995 on he has been department head of the IDA group at Fraunhofer FIRST (since 2001 GMD became Fraunhofer) in Berlin and since 1999 he has has held a joint Professor position of Fraunhofer and University of Potsdam in Neuroinformatics.  He has been lecturing at Humboldt University, Technical University Berlin and University of Potsdam.  In 1999 he received the Annual National Prize for Pattern Recognition (Olympus Prize) awarded by the German Pattern Recognition Society DAGM.  He serves on the editorial board of Computational Statistics, IEEE Transactions on Biomedical Engineering and on program and organization committees of various international conferences.  His research areas include statistical learning theory, neural networks, kernel-based and ensemble learning techniques, time-series analysis, blind source separation.  His present interests are expanded to statistical denoising methods for the analysis of biomedical data, Brain-Computer Interfacing and most recently to Gene-finding.

 

 

Stephen Boyd

http://www.stanford.edu/~boyd/

 

Convex Optimization and Applications

 

Abstract:  In this talk I will give an overview of some major developments in convex optimization that have emerged over the last ten years or so, and briefly describe several typical applications.  The basic idea is that convex problems are fundamentally tractable, in theory and in practice.  The polynomial worst-case complexity results of linear programming have been extended to nonlinear convex optimization, and interior-point methods for nonlinear convex optimization achieve efficiencies approaching that of modern linear programming solvers.  Several new classes of standard convex optimization problems have emerged, including semidefinite programming, determinant maximization, second-order cone programming, and geometric programming.  Like linear and quadratic programming, we have a fairly complete duality theory, and very effective numerical methods for these problem classes. 

 

There has been a steadily expanding list of new applications of convex optimization, in areas such as circuit design, signal processing, statistics, communications, control, and other fields including machine learning.  Convex optimization is also emerging as an important tool for hard, non-convex problems.  Convex relaxations of hard problems provide a general approach for handling hard optimization problems, with applications in combinatorial optimization and robust optimization.

 

This is joint work with Lieven Vandenberghe.

 

Bio:  Stephen Boyd is the Samsung Professor of Engineering and Director of the Information Systems Laboratory, in Stanford's Electrical Engineering Department.  He received the A.B. degree in Mathematics from Harvard University in 1980, and the Ph.D. in Electrical Engineering and Computer Science from the University of California, Berkeley, in 1985, and then joined the faculty at Stanford.  His interests include computer-aided control system design, and convex programming applications in control, signal processing, and circuits.

 

 

Zach Mainen

http://www.cshl.org/public/SCIENCE/mainen.html

 

Neural Coding and the Olfactory System

 

Abstract:  The sense of smell may be more tractable than vision, but the capabilities of natural olfactory systems greatly exceed those of artificial chemical detectors and the fundamental nature of the olfactory neural code remains deeply controversial. The olfactory bulb receives input from about 1000 receptor types arrayed in a stereotyped map.  Thus, odors are represented by a distributed population code that is difficult to study using traditional single-electrode recordings and has only recently begun to be unraveled using molecular techniques, imaging and multi-electrode recordings.  The features that are encoded in this map and the function of lateral inhibitory connections in the bulb remain unclear.  It is commonly believed that olfaction is a slow sense, and the role of time in olfactory coding and computations has long been mysterious and intriguing.  The complexity of spatiotemporal patterns in the olfactory bulb led Walter Freeman to conclude that olfactory dynamics were inherently chaotic.  Evidence for odor coding by temporal synchrony as well as dynamically-evolving representations undergoing of temporal decorrelation has been obtained by Gilles Laurent and his collaborators in the locust, but it is not known whether similar observations hold in mammals.  John Hopfield has developed a theory of olfaction that uses phase coding to explain concentration-invariant odor recognition and odor segmentation, but this theory also remains untested. The motor act of sniffing is integral to the olfactory perception, and physiological evidence suggests that the respiration (theta) cycle is also relevant to coding and sensorimotor integration.  Although the olfactory bulb has been likened to the retina, its activity reflects not only sensory input but hunger and reward expectation, reflecting massive reciprocal connections with neocortical and subcortical structures.  Thus, an understanding of the olfactory system will lead to understanding of the parts of the brain with which it interacts, including the hippocampus, orbitofrontal cortex, amygdala, basal ganglia, and brain stem.

 

This tutorial will present an overview of elements of contemporary theory and experimental data pertinent to olfactory coding and computation.

 

Bio:  Zach Mainen is Assistant Professor at Cold Spring Harbor laboratory.  He received his PhD from the University of California, San Diego in 1995 for work with Terry Sejnowski at The Salk Institute on spike generation in neocortical neurons.  He subsequently worked at Cold Spring Harbor Laboratory as a postdoctoral fellow with Roberto Malinow and Karel Svoboda and joined the faculty in 1999.  His research interests include neural coding, neurotransmitter function, and the neural correlates of behavior.  His laboratory focuses on the rodent olfactory system.  He is the recipient of a Burroughs-Wellcome Career Develpment award and is currently a Searle Scholar.

 

 

David Lowe

http://www.cs.ubc.ca/~lowe/

 

Real-time Object Recognition using Invariant Local Image Features

 

Abstract:  Invariant local features provide a powerful new approach to image matching and recognition.  For the first time, they allow for robust real-time recognition with no prior object segmentation while allowing for high levels of occlusion.  New methods have been developed for rapidly detecting large numbers of features that are invariant to image scale, orientation, and location, and that also carry enough information to select potential matches in a large database of previously seen features.  Reliable recognition is achieved by identifying consistent clusters of features followed by top-down model fitting.  Probabilistic models are used to evaluate feature matches and verify interpretations.

 

This tutorial will provide an introduction to invariant local features and will also include a real-time demonstration of a system for object recognition.  Topics will include interest point detectors, scale invariance, distinctive local descriptors, affine invariance, illumination invariance, the Hough transform, probabilistic models, learning with local features, model fitting, and applications to recognition, image matching, robot localization, and motion tracking.

 

Bio: David Lowe is a professor of computer science at the University of British Columbia.  He received his PhD in computer science from Stanford University in 1984.  From 1984 to 1987 he was an assistant professor at the Courant Institute of Mathematical Sciences at New York University.  From 1987 to 1995 he was a scholar of the Canadian Institute for Advanced Research.  His research interests include object recognition, local invariant features for image matching, robot localization, and models of human visual recognition. He is on the Editorial Board of the International Journal of Computer Vision.  He was co-chair of the International Conference on Computer Vision (ICCV 2001 in Vancouver, Canada).

 

 

Daniel D. Lee

http://www.seas.upenn.edu/~ddlee/

Learning in Sensorimotor Systems

 

Abstract:  Many algorithms in machine learning involve changing the underlying dimensionality of the data set. Unsupervised learning techniques such as principal components analysis typically involve dimensionality reduction, whereas supervised learning techniques such as support vector machines can be understood as mapping the data to a higher dimensional space. After reviewing recent machine learning algorithms that utilize changes in dimensionality, I will show how equivalent problems emerge in artificial sensorimotor systems.  Sensory processing typically involves mapping high-dimensional sensory inputs onto a smaller number of perceptually-relevant features, whereas motor learning involves driving a large number of actuator parameters with a smaller number of control variables.  I will illustrate how dimensionality plays an important role in sensorimotor learning with demonstrations on some prototypical robotic systems.

 

Bio: .Daniel Lee received his bachelor's degree in physics from Harvard in 1990 and his Ph.D. in physics from MIT in 1995.  Afterwards, he was a member of the technical staff at Bell Laboratories, Lucent Technologies, in the Biological Computation and Theoretical Physics Departments until 2001.  He is now an Assistant Professor in the Electrical Engineering and Bioengineering departments at the University of Pennsylvania.  His research focuses on trying to understand the general principles that biological systems use to process and organize information.  He works on applying that knowledge to building better artificial systems for vision, speech, language, and data communications.

 

 

David Karger, Laboratory for Computer Science, EECS, MIT

http://theory.lcs.mit.edu/~karger/

Algorithmic Tools Applied to Learning and Inference Problems

 

Abstract:  While much of the work in machine learning is in modeling a problem and characterizing the desired solution, the final step is often to develop an efficient algorithm for computing the desired solution to the (often quite difficult) problem formulation.  Conversely, a key focus in theoretical computer science is the development of efficient algorithmic solutions for difficult computational problems.  I will try to draw these two fields closer, showing how, for a variety of machine learning problems, tools from algorithmic theory can help make progress on efficient solutions.  In doing so, I will survey a number of techniques from the algorithms toolbox, including random sampling, approximation algorithms, linear programming relaxations and randomized rounding.

 

As examples, I will discuss algorithmic contributions to four specific problems.  The first is near-neighbor search.  Always a key concept in machine learning, it has become a computational bottleneck in recent novel algorithms for learning low dimensional manifolds.  I'll show how random sampling and random walks can be used to give efficient data structures for near neighbor search in such problems.  The second problem arises from a twist on Markov Decision Processes motivated by robot navigation, in which reward is collected only the first time a state is visited.  This change breaks all the traditional dynamic programming approaches to MDPs -- while they can be applied by exponentiating the state space, such a solution is not practical.  I'll show instead how to develop an approximate solution by connecting it to theoretical computer science's extensive library of approximation algorithms, specifically for problems such as traveling salesman.  Third, I'll look at decoding turbo codes.  While the goal of finding the maximum likelihood codeword given a corrupted received word is easily specified, very little is known about how to accomplish it efficiently---despite the fact that turbo codes seem to do extremely well in practice.  I'll show how turbo decoding can be formulated as an integer linear programming problem, and tackled using machinery from fractional linear programming and maximum flows.  The result is the first provably good decoder for rate-1/2 turbo codes, with consequences for codes of other rates as well.  Finally, I will talk about learning low-treewidth graphical models.  Low-treewidth graphical models are attractive because inference can be done efficiently on them.  Such models may be specified as part of modeling the problem, but I will look instead at the problem of inferring a properly structured model from data.  I'll show how to express this problem as an (NP-complete) generalization of the minimum spanning tree problem (much as Chou and Liu did for models of treewidth 1).  Then I will introduce the technique of randomized rounding of linear programs to derive an approximately optimum solution to the problem.

 

The material presented reflects joint work with Avrim Blum, Shuchi Chawla, Jon Feldman, Terran Lane, Adam Meyerson, Maria Minkoff, Matthias Ruhl, and Nati Srebro.

 

Bio:  David R. Karger is an Associate Professor of Computer Science and a member of the Laboratory for Computer Science at MIT.  He received his A.B. in Computer Science and Physics from Harvard University in 1989 and his Ph.D. in Computer Science from Stanford University in 1994.  He was the recipient of the 1995 ACM Doctoral Dissertation award, the 1997 Mathematical Programming Society Tucker Prize, and the 2003 NAS Award for Initiatives in Research.  He is a member of the executive committee of SIGACT, ACM's theoretical computer science group. 

 

His research interests include algorithms and randomization, both in a theoretical context and in application contexts in areas such as systems, networking, artificial intelligence, coding theory, and compilers.  He also explores systems and user interfaces to help organize, navigate, and retrieve information.