Name of Speaker Dr. Daniel Pimentel Alarcon

Place: CS Conference Room, 755 in 25 PP Building

Time: 11:00 am – noon on Wednesday, February 15

Title: Learning Subspaces by Pieces

Abstract: Subspaces lie at the heart of data analysis. As soon as we get our hands on some data, finding a subspace that explains it is one of the first things we try, for example, using Principal Component Analysis (PCA) or linear regression.

Many applications have missing data and gross errors. For example, in computer vision, occlusions produce missing data, and foreground can be modeled as gross errors; in surveys and recommender systems, subjects do not know or do not want to provide all information; in networked systems it is impossible or impractical to measure all components.

In this talk I will present our recent results on when and how subspaces can be identified from highly incomplete and corrupted data.  The main idea is to analyze the algebraic structure of small pieces of subspaces to then stitch them together. This gives rise to new algorithms and theoretical insights regarding low-rank matrix completion, robust PCA, coherence, arbitrary (non-uniform) samplings, lower bounds, and computational complexity, among others. This also opens the door to study more complex data structures, like unions of subspaces and manifolds.

I will discuss applications of our results in areas as diverse as astronomy, drug discovery, networks estimation, computer vision, rigidity theory, tensors, recommender systems, phylogenetics, wood classification and deep learning.

Rajshekhar Sunderraman
Professor and Acting Chair
Computer Science Department
Georgia State University
P.O. Box 5060
Atlanta, GA 30302-5060

phone: (404)413-5726 fax: (404)413-5717