Bidirectional use of knowledge in the multi-modal NL access system XTRA

Abstract

The acceptability and effectiveness of an expert system is critically dependent on its user interface. Natural language could be a well-suited communicative medium; however, current NL interfaces to expert systems show an impeding number of shortcomings. In this paper, it is shown how the XTRA system-a German NL interface between a user and one of various expert systems- employs a framework of novel AI techniques to overcome these shortcomings: it uses various highly interacting knowledge sources for domain-independent linguistic knowledge and for domain-specific world knowledge. This supports the view of NL as a universal communicative medium. In order to allow for a communicatively adequate dialog processing, knowledge sources are bidircctionaly used by both the analysis and the generation component. Both are enhanced with knowledge about