Dr. Sergios Theodoridis
Dept. of Informatics and Telecommunications
University of Athens, Greece

Room BA1190
Bahen Centre for Information Technology
University of Toronto
40 St. George Street
Toronto, M5S 2E4   map
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The task of parameter/function estimation has been at the center of scientific attention for a long time and it comes under different names such as filtering, prediction, beamforming, curve fitting, classification, regression.

In this talk, the estimation task is treated in the context of set theoretic estimation arguments. Instead of a single optimal point, we are searching for a set of solutions that are in agreement with the available information, which is provided to us in the form of a set of training points and a set of constraints. Each point in the training data set, as well as each one of the constraints, is associated with a convex set, constructed according to a (convex) loss function (differentiable or not).

The goal of this talk is to present a general tool for parameter/function estimation, under a set of convex constraints, both for classification as well as regression tasks, in a time adaptive setting in (infinite dimensional) Reproducing Kernel Hilbert spaces (RKHS).

The algorithmic scheme consists of a sequence of projections, of linear complexity with respect to the number of unknown parameters. Our theory proves that such a scheme converges to the intersection of all (with the possible exception of a finite number of) the convex sets, where the required solution lies. The performance of the methodology is demonstrated in the context of nonlinear classification and robust beamforming in communication systems.

The work has been carried out in cooperation with Kostas Slavakis and Isao Yamada.

Sergios Theodoridis is currently Professor of Signal Processing and Communications in the Department of Informatics and Telecommunications of the University of Athens. His research interests lie in the areas of Adaptive Algorithms and Communications, Machine Learning and Pattern Recognition, Signal Processing for Audio Processing and Retrieval. He is the co-editor of the book "Efficient Algorithms for Signal Processing and System Identification", Prentice Hall 1993, the co-author of the book "Pattern Recognition", Academic Press, 4th Ed. 2009, and the co-author of three books in Greek, two of them for the Greek Open University.

He is the co-author of four papers that have received best paper awards, including the IEEE Computational Intelligence Society Transactions on Neural Networks Outstanding Paper Award. He currently serves as Distinguished Lecturer of the IEEE Signal Processing Society.

He has served as President of EURASIP and he is currently a member of the Board of Governors for the IEEE CAS Society. He was the general chairman of EUSIPCO-98, the Technical Programme co-chairman of ISCAS-2006 and the Co-chairman of CIP-2008. He has served as an Associate Editor in all major Signal Processing related journals, including IEEE Transactions on Signal Processing, IEEE Signal Processing Magazine, IEEE Transactions on Neural networks, IEEE Transactions on Circuits and Systems, Signal Processing. He is currently the Editor-in-Chief of the EURASIP Book series on SP of Academic Press.

He is a member of the Greek National Council for Research and Technology and Chairman of the SP advisory committee for the Edinburgh Research Partnership (ERP). He has served as vice chairman of the Greek Pedagogical Institute and he was for four years member of the Board of Directors of COSMOTE (the Greek mobile phone operating company). He is Fellow of IET, a Corresponding Fellow of RSE and a Fellow of IEEE.