Using POMDPs for Spoken Dialogue Management

Steve Young
Cambridge University

Monday, December 3, 2007 at 1:00PM

54-134 Engineering IV Building
Refreshments Served

Abstract: Modelling dialogue management as a Markov Decision Process offers many potential advantages including the ability to learn dialog strategies from data, increased robustness to noise and on-line adaptation. However, attempts to exploit MDPs in real systems have met with limited success primarily due to the fact that they cannot model the uncertainty which is inherent in all spoken dialogue systems. This talk will explain how partially observable Markov Decision Processes (POMDPs) can provide a principled mathematical framework for modelling the inherent uncertainty in spoken dialog systems. It briefly summarises the basic mathematics and explains why exact optimisation is intractable. It then describes a form of approximation called the Hidden Information State model which does scale and which can be used to build practical systems.

Biography: Steve Young is Head of Information Engineering at Cambridge University, UK. He received a BA in Electrical Sciences from Cambridge University in 1973 and a PhD in Speech Processing in 1978. He held lectureships at both Manchester and Cambridge Universities before being elected to the Chair of Information Engineering at Cambridge University in 1994. He was a co-founder and Technical Director of Entropic Ltd from 1995 until 1999 when the company was taken over by Microsoft. After short period as an Architect at Microsoft, he returned full-time to the University in January 2001. Steve Youngs research interests include speech recognition, language modelling, spoken dialogue and multi-media applications. He is the inventor and original author of the HTK Toolkit for building hidden Markov model-based recognition systems (see http://htk.eng.cam.ac.uk). More recently his prime interest has shifted to statistical dialogue systems and the use of Partially Observable Markov Decision Processes for modelling them. He also has active research in voice transformation and synthesis. He has written and edited books on software engineering and speech processing, and he has published as author and co-author, more than 200 papers in these areas. He is a Fellow of the Royal Academy of Engineering, the Institute of Electrical Engineers and the Royal Society of Arts. He served as the senior editor of Computer Speech and Language from 1993 to 2004 and is now a member of the editorial board. He is a Senior Member of the IEEE and a member of the SPS Awards Committee. He was a member of the IEEE STC Committee from 1997 to 1999 and he has served on the technical committees of numerous workshops and conferences. He was the recipient of an IEEE Signal Processing Society Technical Achievement Award in 2004.