On the Use of Context in Building Spoken Language Dialogue Systems for Large Tasks

Context is of crucial importance to language understanding in general and plays a central role in spoken language dialogue systems design. Context, however, is hard to define. In this paper context is viewed as denoting a collection of aspects or contextual elements each of which may be defined and analysed with respect to its specific contribution to dialogue understanding. Massive exploitation of context is essential in spoken language dialogue systems design for large tasks because the feasibility of such systems demands a high degree of control of the user-system dialogue. The paper discusses in detail how knowledge about contextual elements is used in system-directed dialogue design to achieve an optimal trade-off between technological feasibility and user acceptability and to enable controlled steps in the direction of mixed-initiative dialogue. The discussion is based on the design, implementation and test of systemdirected dialogue for a spoken language dialogue system and on first experiments towards achieving mixedinitiative dialogue.