Exploring Topic Continuation Follow-up Questions using Machine Learning Manuel Kirschner author Raffaella Bernardi author 2009-06 text Proceedings of Human Language Technologies: The 2009 Annual Conference of the North American Chapter of the Association for Computational Linguistics, Companion Volume: Student Research Workshop and Doctoral Consortium Ulrich Germann editor Chirag Shah editor Svetlana Stoyanchev editor Carolyn Penstein Rosé editor Anoop Sarkar editor Association for Computational Linguistics Boulder, Colorado conference publication kirschner-bernardi-2009-exploring https://aclanthology.org/N09-3003/ 2009-06 13 18