Abstract

The Philips SUSI system is a set of modules for the construction of automatic inquiry systems such as the train timetable information system TABA and the Philips Automatic Directory Information System (PADIS). These systems conduct a dialogue in continuous spontaneous speech with the user, giving access to information in a database. To improve the system behaviour we have extended the knowledge representation and update functions of the SUSI system so that they collect and use the negative knowledge during the dialogue. Negative knowledge in this context is the information that results from denials by the user in the dialogue, such as "No" and "Not Mr. Smiths". The negative knowledge handling has been implemented and tested for the SUSI based application PADIS. For PADIS, we found that certain dialogues improve significantly because of the use of negative knowledge.