Abstract

1This work was supported in part by the projects TRINDI (Task Oriented Instructional Dialogue), EC Project LE4-8314, SDS (Swedish Dialogue Systems), NUTEK/HSFR Language Technology Project F1472/1997, INDI (Information Exchange in Dialogue), Riksbankens Jubileumsfond 1997-0134, and SIRIDUS (Specification, Interaction, Reconfiguration in Dialogue Understanding Systems), EC Project IST-1999-10516, and ILT (Interactive Language Technology), Vinnova Project 2001-6340. To appear in Presuppositions and Discourse ed. by Rainer Bäuerle, Uwe Reyle and Thomas Ede Zimmermann, Elsevier, Amsterdam