A Metalanguage Representation of Relational Databases for Deductive Question-Answering Systems

Abstract

This paper 1 presents a method of formally representing the information that exists in a relational database. The primary utility of such a representation is for deductive questionanswering systems that must access an existing relational database . To respond intelligently to user inquiries, such systems must have a more complete representation of the domain of discourse than is generally available in the database . The problem that then arises is how to reconcile the information present in th e database with the domain representation, so that database queries can be derived to answer the user's inquiries. Here we take the formal approach of describing a relational database as the model of a first-order language. Another firstorder language, the metalanguage, is used both to represent the domain of discourse, and Lo describe the relationship of the database to the domain . This view proves particularly useful in two respects . First, by axiomatizing the database language and its associated model in a metatheory, we are able to describe in a powerful and flexible manner how the database corresponds to the domain of discourse. Secondly, viewing the database as a mechanizable model of the database language enables us to take advantage of the computational properties of database query language processors. Once a database query that is equivalent to an original query is derived, it can be evaluated against the database to determine the truth of the original query . Thus the algebraic operations of the database processor can be incorporated in an elegant way into the deductive process of questionanswering .