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Seminar Details

Date 8-1-2007
Time 14:30
Room/Location Sala conferenze DISI-3 piano
Title Multi-task Feature Learning
Speaker Massimiliano Pontil
Affiliation University College London - UK
Link http://www.econ.ucl.ac.uk/index.php
Abstract We present a method for learning a low dimensional representation which is shared across a set of multiple related tasks. The method builds upon the well-known 1-norm regularization problem using a new regularizer which controls the number of learned features common for all the tasks. We show that this problem is equivalent to a convex optimization problem and develop an iterative algorithm for solving it. The algorithm has a simple interpretation: it alternately performs a supervised and an unsupervised step, where in the latter step we learn common-across-tasks representations and in the former step we learn task-specific functions using these representations. We report experiments on a simulated and a real data set which demonstrate that the proposed method dramatically improves the performance relative to learning each task independently. Our algorithm can also be used, as a special case, to simply select -- not learn -- a few common features across the tasks. This is joint work with Andreas Argyriou and Theodoros Evgeniou
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