The use of syntax, semantics, and pragmatics in the KEAL speech understanding system

Abstract

KEAL is a speech understanding system currently under development at the French Telecommunication Research Center (CNET) in Lannion; it aims to study oral man‐machine communication. KEAL is typically designed for automatic inquiry. Such a task requires dialog procedures in order to provide naturalness in the inquiry process. On the other hand, the use of dialog allows to achieve good comprehension despite the presently limited performances of KEAL at the phonetic level. This paper describes how syntactic, semantic and pragmatic knowledges are used in KEAL. Sentence recognition is performed by a bottom‐up left‐to‐right parser which provides also the parse‐tree of the sentence. This parse‐tree is then interpreted in order to extract the semantic information which is relevant to the dialog. The semantic information is used by the dialog controller for instantiating a model‐graph, which represents the state of the dialog at any moment. The dialog controller sends a response to a text‐to‐speech synthesizer, and indicates how to analyze the user's reply. An example taken from automatic directory assistance service is described; results concerning preliminary experiments are discussed.