<?xml version="1.0" standalone="yes"?>
<Paper uid="E85-1030">
  <Title>A NATUWAL LANGUAGE INTERFACE USING A WORLD MODEL</Title>
  <Section position="2" start_page="0" end_page="0" type="intro">
    <SectionTitle>
INTRODUCTION
</SectionTitle>
    <Paragraph position="0"> KID (Knowledge-based Interface to Databases) is a Japanese-language database interface (Izumida, 84). KID has the following four features.</Paragraph>
    <Paragraph position="1"> 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.</Paragraph>
    <Paragraph position="2"> 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.</Paragraph>
    <Paragraph position="3"> 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.</Paragraph>
    <Paragraph position="4"> 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.</Paragraph>
    <Paragraph position="5"> 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 files and fields. In KID, the mapping information between the model of the domain and the database schema is described in the world model, so the user does not have to worry about any changes in the database schema.</Paragraph>
    <Paragraph position="6"> Knowledge of the query language of a database system is represented separately as production rules. Thus, the user only has to change these rules if there are changes in the database system. In this paper we will focus on the first three features of KID. Firstly, we will explain the world model, then the overall structure of the KID, the morphological analyzer (required to process Japanese-language sentences), the model-based parser, semantic interpretation and the flow of the parsing process, knowledge for customizing KID and, lastly, the evaluation of KID and its results.</Paragraph>
  </Section>
class="xml-element"></Paper>