A Natural Language Interface Using a World Model

A NATUWAL LANGUAGE INTERFACE USING A WORLD MODEL Yoshio Izumida, Hiroshi Ishikawa, Toshiaki Yoshino, Tadashi Hoshiai, and Akifumi Makinouchi Software Laboratory Fujitsu Laboratories Ltd. 1015 kamikodanaka, Nakahara-ku, Kawasaki, 211, Japan ABSTRACT Databases are nowadays used by varied and diverse users, many of whom are unfamiliar with the workings of a computer, but who, nevertheless, want to use those databases more easily. Rising to meet this demand, authors are developing a Japanese language interface, called KID, as a database front-end system. KID incorporates a world model representing application and database knowledge to help make databases easier to use. KID has the following features: (I) parser extendability and robustness, (2) independence from the application domain, (3) ease of knowledge editing, (4) independence from the database. This paper focuses on the first three features. KID has already been applied to the fields of housing, sales, and drug testing, thus confirming its transportability and practicality. INTRODUCTION KID (Knowledge-based Interface to Databases) is a Japanese-language database interface (Izumida, 84). KID has the following four features. Extendability and robustness Natural language sentences employ a wide variety of expressions. A parser must always be extended to understand new sentences. A parser which can understand one set of sentences is often incapable of understanding another set of sentences. In KID, parsing rules are grouped into packets and the parsing mechanism is simple, thus making KID highly extendable. The system must be robust, in order to handle conversational sentences, which often contain errors and ellipses. To interpret these ill-formed sentences, semantic interpretation must play a leading role. KID has an integrated knowledge base called the world model. The world model represents the semantic model of the domain of the discourse in an object-oriented manner. Several systems (e.g., Ginsparg, 83) use a semantic model to interpret ill-formed sentences, but the use of the semantic model is unclear. We have made the semantic interpretation rules clear according to the structure of the world model and syntactic information of the input sentences. This helps the parsing of ill-formed sentences. Independence from the application domain The system must be easily adaptable to different applications. The domain-dependent knowledge must be separate from the domain- independent knowledge. In many systems (e.g., Waltz, 78 and Hendrix, 78), the domain-dependent knowledge is embedded within the parsing rules, thus reducing the system's transportability. In KID, the domain-dependent knowledge is integrated into the world model separately, therefore giving KID high transportability. Ease of knowledge editing The world model contains various kinds of knowledge, and the editing of this knowledge must be easy to accommodate various levels of users. KID provides users with the world model editor, this having a separate user interface for each user level. The world model editor makes the customization and extension of the KID system easy. Independence from the database The system must be able handle changes in the database system and schema easily. In TEAM (Gross, 83), the schema information is separate, but the user must be familiar with the database schema such as …

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