tailieunhanh - Báo cáo khoa học: "ACCOMMODATING CONTEXT CHANGE"

Two independent mechanisms of context change have been discussed separately in the literature context change by entity introduction and context change by event simulation. Here we discuss their integration. The effectiveness of the integration depends in part on a representation of events that captures people's uncertainty about their outcome - in particular, people's incomplete expectations about the changes effected by events. We propose such a representation and a process of accommodation that makes use of it, and discuss our initial implementation of these ideas. . | ACCOMMODATING CONTEXT CHANGE Bonnie Lynn Webber and Breck Baldwin Department of Computer and Information Science University of Pennsylvania Philadelphia PA 19104-6389 Internet bonnie@central breck@linc . ABSTRACT Two independent mechanisms of context change have been discussed separately in the literature -context change by entity introduction and context change by event simulation. Here we discuss their integration. The effectiveness of the integration depends in part on a representation of events that captures people s uncertainty about their outcome - in particular people s incomplete expectations about the changes effected by events. We propose such a representation and a process of accommodation that makes use of it and discuss our initial implementation of these ideas. Introduction Consider the following example Example 1 John made a handbag from an inner-tube. a. He sold it for twenty dollars. b. He sold them for fifty dollars. c. He had taken it from his brother s car. d. Neither of them was particularly useful. Here two entities are introduced via indefinite noun phrases NPs in the first sentence. The alternative follow-ons a-d show that subsequent reference to those entities is constrained. In particular b highlights the difference in their existential status even though there is no syntactic difference in how they are introduced. Now consider This work was partially supported by ARO grant DAAL 03-89-C-0031 DARPA grant N00014-90-J-1863 and NSF grant IRI 90-16592 to the University of Pennsylvania. The paper draws upon material first presented at the workshop on Defeasible Reasoning in Semaniics and Pragmatics held at the European Summer School on Logic Language and Information Saarbrũcken Germany August 1991. Example 2 Mix the flour butter and water. a. Knead the dough until smooth and shiny. b. Spread the paste over the blueberries. c. Stir the batter until all lumps are gone. In each of the alternative follow-on a-c a different definite NP .