Project Summary: Linguistic Knowledge Sources for Spoken Language Understanding

The objective of the Unisys Spoken Language Systems effort is to develop and demonstrate technology for the understanding of goal-directed spontaneous speech input. The Unisys spoken language architecfure couples a speech recognition system (the MIT Summit system) with the Unisys discourse understanding system Pundit. Pundit is a broad-coverage language understanding system used in a variety of message understanding applications and extended to handle spoken language input. Its power comes from the integration of syntax, semantics and pragmatics (context), the ability to port r~pidly to new task domains, and from an open, modular architecture. Pundit is unique in its ability to handle connected discourse; it includes a reference resolution module that tracks "discourse entities" and distinguishes references to previously mentioned entities from the introduction of new entities. The Pundit front-end supports turn-taking dialogue and permits the system to include both questions and answers in building an integrated discourse context, required for the handling of interactive communication. Pundit has been interfaced to speech recogaition systems (both Summit and the 1TT continuous speech recogniser) to perform applications on directionfinding assistance (Voyager), air travel planning (ATIS), and air traffic control (Right strip updating).