Seminars/Colloquia/Invited Talks

Seminars

Brendan Frey

Affinity Propagation: Discovering Motifs in Images, Genomes and Text

PLACE:	Clark 110
EVENT:	CIS Seminar
DATE:	February 5, 2008
TIME:	1:00 - 2:00 PM

Abstract

An important problem in science and engineering is how to find and associate constituent patterns or motifs in large amounts of high-dimensional data. Examples include the identification and modeling of object parts in images, and the detection and association of RNA motifs that regulate tissue-dependent gene splicing in mammals. One approach is to identify a subset of representative data exemplars that are used to summarize and model the data. This is an NP-hard problem that is traditionally solved approximately by randomly choosing an initial subset of data points and then iteratively refining it. I'll describe a method called 'affinity propagation', which takes as input measures of similarity between pairs of data points. Real-valued messages are exchanged between data points until a high-quality set of exemplars and corresponding clusters gradually emerges. Affinity propagation is a general-purpose method, but I'll describe its application to problems in image analysis, genomics, transcriptomics and document analysis. I'll outline open problems and possible future directions of research, including issues surrounding potential hardware implementation.

Brief Biography:

Brendan Frey received his PhD from the University of Toronto in 1997. From 1997 to 1999, he was a Beckman Fellow at the University of Illinois at Urbana Champaign and then he joined the Department of Computer Science at the University of Waterloo as an Assistant Professor. In 2001, Dr. Frey moved to the University of Toronto, where he is now a Full Professor in Electrical and Computer Engineering, with cross-appointments to Computer Science and the Centre for Cellular and Bio-molecular Research. He has consulted for Microsoft Research and various startup companies in the Toronto area. Dr. Frey is the author of the book Graphical Models for Machine Learning and Digital Communication and he has published over 100 papers and given over 100 invited talks on machine learning, probabilistic graphical models, molecular biology, computer vision and iterative decoding. Dr. Frey's most highly-cited work is on 'factor graphs and the sum-product algorithm'. In 2005, Dr. Frey's work on computational 'epitomes' with applications in vision received honorable mention for Best Paper at the IEEE Conference on Computer Vision and Pattern Recognition. Dr. Frey's 2005 Nature Genetics paper reporting the first-ever exon-resolution analysis of the mammalian genome stirred up controversy in the molecular biology and genomics communities, which was reconciled in his group's favour in the March 2006 issue of Science. Dr. Frey's most recent work is on a machine learning algorithm called affinity propagation, which was described in the Feburary 16, 2007 issue of Science. Dr. Frey's primary research interests include probabilistic inference, machine learning, information processing, molecular biology and computational vision.
Dr. Frey is a Fellow of the Canadian Institute for Advanced Research, a 2007 recipient of Canada's Top 40 Under 40 Award, a Canada Research Chair in Information Processing and Machine Learning, a winner of the Premier's Research Excellence Award, a former Fellow of the Beckman Foundation, and a recipient of the NSERC 1967 Science and Engineering Award.