Updating Discourse Context with Active Logic

In this paper we present our implementation of a system of active logicthat processes natural language discourses. We focus on problems that
involve presupposition and the associated well-known problems of the
projection of presupposition. We discuss Heim's largely successful theory
of presupposition and point out certain limitations. We then use these
observations to build our discourse processor based on active logic. Our
main contributions are the handling of problems that go beyond the scope
of Heim's theory , especially discourses the involve cancellation of
presupposition. Ongoing work suggests that conversational implicature and
the cancellation of implicature can also be treated by our methods. Key
words: presupposition, discourse, con text, accommodation, active logic,
implicature.
(Also cross-referenced as UMIACS-TR-96-62)