[Colloquium] REMINDER: Talks at TTIC: Ulas Ayaz, Brown University

[Dawn Ellis]

When:     Monday, March 9, 2015 at 2pm

Where:    TTIC, 6045 S Kenwood Avenue, 5th Floor, Room 526

Who:       Ulas Ayaz, Brown University

Title:       Subspace Clustering with Ordered Weighted L1 Minimization

Abstract:

We consider the problem of clustering a collection of N unlabaled data
points assumed
to lie near a union of k lower dimensional planes. This assumption works in
certain computer vision applications such as face recognition and image
segmentation. Elhamifar and Vidal have proposed “Sparse Subspace Clustering
(SSC)” algorithm to solve this problem which has also been theoretically
analyzed by Candès and Soltanolkotabi. This algorithm basically solves `1
minimization program for each data point. We consider an alternative
algorithm which only solves k many convex optimizations to achieve the
clustering. We do not know in advance how many subspaces there are nor do
we have any information about their dimensions. Our motivation is a recent
result by Figueiredo and Nowak where they employ “ordered weighted `1
regularization (OWL)” in linear regression with strongly correlated
variables. Given this power of OWL, we employ a similar technique for
subspace clustering problem where we can assume apriori that the data
points on the same subspace are highly correlated with each other when
compared to other data points. We present experimental results to show the
efficiency of the algorithm and also give preliminary theoretical results
about its performance.

Bio:
“I completed my Ph.D. in Mathematics at the Hausdorff Center of Mathematics
in Bonn under the supervision of Prof. Holger Rauhut. Earlier I was at UBC
for my M.Sc. working on signal quantization with Prof. Ozgur Yilmaz. My
primary research interests are in mathematical signal processing, random
matrix theory, frame theory, geometric functional analysis and compressed
sensing.  I am especially interested in the analysis of sparse and
low-dimensional representations of high-dimensional data. Recently I have
been interested in certain machine learning problems. I am a postdoctoral
fellow at ICERM, Brown University for the 2014-2015 academic year. Before
coming to ICERM, I worked with SONY Corporation on a research project for
applying compressed sensing to image sensors.”


Host:  Nati Srebro, nati at ttic.edu




-- 
*Dawn Ellis*
Administrative Coordinator,
Bookkeeper
773-834-1757
dellis at ttic.edu

TTIC
6045 S. Kenwood Ave.
Chicago, IL. 60637
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