[Compstats] Talk Wed @ 2:30: Ali Ghodsi

Pascal Poupart ppoupart at cs.uwaterloo.ca
Wed Feb 10 13:19:25 EST 2010


Quick reminder about Ali's talk today at 2:30pm in the AI seminar room 
(DC2306C).
Pascal

Pascal Poupart wrote:
> Hi everyone,
>
> Ali Ghodsi will give this weeks talk (title and abstract below).  Note 
> that we will hold the seminar at *2:30 pm* (instead of 4pm).
>
> Pascal
> ====================
>
> Title: Learning a non-parametric mapping  for Non-linear
> Dimensionality Reduction
>
> Speaker: Ali Ghodsi
> Date: Wed Feb 10
> Time: 2:30 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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