Speech Dialogue Systems -- A "Pragmatics-First'' Approach to Rational Interaction

The general goal in implementing dialogue systems is in most cases to provide some kind of human-computer-interface for rational interaction. For that purpose, an approach is required which enables such a system to satisfy user goals in a given (ideally open) domain by conducting spoken dialogues. Furthermore, it should be possible to augment it by other kinds of multi-modal interaction like gestures or the selection of items from a menu on a screen. Interactions are called “rational” because rationality principles — at the knowledge representation level — should be applied to optimally select appropriate communicative actions. In this article, different approaches to the understanding of dialogues and the implementation of dialogue systems will be presented. As a basis for comparing the approaches, fundamental issuses of language understanding, speech act theory, and theories of rational interaction are outlined. To give an impression of their implications for the implementation of dialogue systems, we refer to the system framework developed in Erlangen, which has been applied in various projects, as a show case throughout the paper.