Writing a natural language data base system

We present a model for processing English requests for information from a relational data base. The model has as its main steps (a) locating semantic constituents of a request; (b) matching these constituents against larger templates called concept case frames; (c) filling in the concept case frame using information from the user's request, from the dialogue context and from the user's responses to questions posed by the system; and (d) generating a formal data base query using the collected information. Methods are suggested for constructing the components of such a natural language processing system for an arbitrary relational data base. The model has been applied to a large data base of aircraft flight and maintenance data to generate a system called PLANES; examples are drawn from this system.