Discourse Pragmatics in Task-Oriented Natural Language Interfaces

This paper reviews discourse phenomena that occur frequently in task-oriented man-machine dialogs, reporting on an empirical study that demonstrates the necessity of handling ellipsis, anaphora, extragrammaticality, inter-sentential metalanguage, and other abbreviatory devices in order to achieve convivial user interaction. Invariably, users prefer to generate terse or fragmentary utterances instead of longer, more complete "stand-alone" expressions, even when given clear instructions tO the contrary. The XCALIBUR exbert system interface is designed to meet these needs, including generalized ellipsis resolution by means of a rule-based caseframe method superior to previous semantic grammar approaches.