Time:2:15-3:30pm, Friday, Sept. 7 Place: Science Center. Room 4102, CUNY Graduate Center. 5th ave between 34th and 35th Sts. Title: Structured Perceptron with Inexact Search Speaker: Liang Huang Affiliation: Queens College and Graduate Center, City University of New York Abstract: Structured learning with inexact inference is a fundamental problem in machine learning with wide applications in natural language processing and other structured domains where exact inference is often intractable, for example in parsing and machine translation. This work develops a general theory of structured perceptron learning under inexact inference. We aim to train a search-specific, search-error-robust model that can "live with" search errors and reach the true output regardless of how inaccurate the search is. Specifically, we propose variants of the structured perceptron algorithm under a general ``violation-fixing'' framework that guarantees convergence (under new definitions of separability). This framework subsumes previous remedies including ``early update'' of Collins and Roark (2004) as special cases (and thus establishing a theoretical justification for early update), and also explains why standard perceptron may fail with inexact search. We also propose new update methods within this framework which learn better models with dramatically reduced training times on state-of-the-art part-of-speech tagging and incremental parsing systems. Bio: Liang Huang has just joined CUNY as an Assistant Professor of Computer Science at Queens College and CS doctoral faculty member at the Graduate Center. He received his Ph.D. from the University of Pennsylvania in 2008, and worked briefly at Google as a Research Scientist before switching to the University of Southern California as a Research Assistant Professor. His research focuses on efficient search algorithms for natural language processing, esp. in parsing and machine translation, as well as related structured learning problems. His work received a Best Paper Award at ACL 2008, and three Best Paper Nominations at ACL 2007, EMNLP 2008, and ACL 2010. He is also a recipient of the Google Faculty Research Award (2010). Besides research he has a great passion for teaching and received the prestigious University Prize for Graduate Teaching at Penn. He is currently looking for bright students and postdocs in NYC so drop him a note if you are interested.