tailieunhanh - Báo cáo khoa học: "LINGUISTIC COHERENCE: A PLAN-BASED ALTERNATIVE"

To fully u n d e r s t a n d a sequence of utterances, one must be able to infer implicit relationships b e t w e e n the utterances. A l t h o u g h the identification of sets of utterance relationships forms the basis for many theories of discourse, the f o r m a l i z a t i o n and recognition of such relationships has p r o v e n to be an e x t r e m e l y difficult c o m. | LINGUISTIC COHERENCE A PLAN-BASED ALTERNATIVE Diane J. Litman AT T Bell Laboratories 3C-408A 600 Mountain Avenue Murray Hill NJ 079741 ABSTRACT To fully understand a sequence of utterances one must be able to infer implicit relationships between the utterances. Although the identification of sets of utterance relationships forms the basis for many theories of discourse the formalization and recognition of such relationships has proven to be an extremely difficult computational task. This paper presents a plan-based approach to the representation and recognition of implicit relationships between utterances. Relationships are formulated as discourse plans which allows their representation in terms of planning operators and their computation via a plan recognition process. By incorporating complex inferential processes relating utterances into a plan-based framework a formalization and computability not available in the earlier works is provided. INTRODUCTION In order to interpret a sequence of utterances fully one must know how the utterances cohere that is one must be able to infer implicit relationships as well as non-relationships between the utterances. Consider the following fragment taken from a terminal transcript between a user and a computer operator Mann 12 Could you mount a magtape for me It s tape 1. Such a fragment appears coherent because it is easy to infer how the second utterance is related to the first. Contrast this with the following fragment Could you mount a magtape for me It s snowing like crazy. This sequence appears much less coherent since now there is no obvious connection between the two utterances. While one could postulate some connection . the speaker s magtape contains a database of places to go skiing more likely one would say that there is no relationship between the utterances. Furth- This work was done at the Department of Computer Science. University of Rochester. Rochester NY 14627. and supported in part by DARPA under Grant .