There is no common ground in human-robot interaction Geert-Jan Kruijff author 2012-09 text Proceedings of the 16th Workshop on the Semantics and Pragmatics of Dialogue - Invited Talks SEMDIAL Paris, France conference publication kruijff-2012-common http://semdial.org/anthology/Z12-Kruijff_semdial_0003.pdf 2012-09