[Compstats] Wed Feb 24 @ 4pm: Ali Ghodsi (part II)

Pascal Poupart ppoupart at cs.uwaterloo.ca
Tue Feb 23 17:59:51 EST 2010

Quick reminder: Ali Ghodsi will give the second part of his talk 
tomorrow at 4pm.

Pascal Poupart wrote:
> Hi everyone,
> There won't be any compstats seminar tomorrow since it is the reading 
> break.  Ali Ghodsi will give part II of his talk next week (Wed Feb 
> 24) @ 4pm in the AI lab.
> cheers,
> Pascal
> ====================
> Title: Learning a non-parametric mapping  for Non-linear
> Dimensionality Reduction (part II)
> Speaker: Ali Ghodsi
> Date: Wed Feb 24
> Time: 4 pm
> Location: AI lab (DC2306C)
> The foremost nonlinear dimensionality reduction algorithms provide an
> embedding only for the given training data, with no straightforward
> extension for the test
> points. This shortcoming makes them unsuitable for problems such as
> classification and regression. On the other hand, linear
> dimensionality reduction algorithms are capable of handling the
> out-of-sample examples easily, but their effectiveness is limited by
> the linearity of the subspace they reveal. In this talk I propose a
> novel dimensionality reduction algorithm which learns a parametric
> mapping between the high-dimensional space and the embedded space. The
> key observation is that when the dimensionality of the data is greater
> than its quantity, it is always possible to find a linear
> transformation that preserves a given subset of distances, while
> changing the distances of another subset. We present a method that
> first maps the points into a high-dimensional feature space, and then
> explicitly searches for an affine transformation that preserves the
> local distances while pulling the non-neighbor points as far apart as
> possible. We formulate this search as an instance of semi-definite
> programming. The resulted transformation can then be used to map
> out-of-sample points into the embedded space.
> This is a joint work with Pooyan Khajehpour

Pascal Poupart
Associate Professor
David R. Cheriton School of Computer Science
University of Waterloo
200 University Avenue West
Waterloo, Ontario
Canada N2L 3G1
Web: http://www.cs.uwaterloo.ca/~ppoupart
Email: ppoupart at cs.uwaterloo.ca 
Telephone: 1-519-888-4567x36239 
Fax: 1-519-885-1208

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