Flexible Speech Act Based Dialogue Management Eli Hagen author Fred Popowich author 2000-10 text 1st SIGdial Workshop on Discourse and Dialogue Association for Computational Linguistics Hong Kong, China conference publication hagen-popowich-2000-flexible 10.3115/1117736.1117751 https://aclanthology.org/W00-1015/ 2000-10 131 140