An efficient easily adaptable system for interpreting natural language queries

TLDR

The paper presents Chat‑80, a prototype natural language question‑answering system designed to be efficient and easily adaptable to various applications. Chat‑80 is implemented in Prolog, uses extraposition grammars to translate English questions into logical form, then applies a planning algorithm to optimize and execute the query against a relational database. In a world‑geography domain, Chat‑80 answers most English‑subset questions in under one second, even for relatively complex queries.

Abstract

This paper gives an overall account of a prototype natural language question answering system, called Chat-80. Chat-80 has been designed to be both efficient and easily adaptable to a variety of applications. The system is implemented entirely in Prolog, a programming language based on logic. With the aid of a logic-based grammar formalism called extraposition grammars, Chat-80 translates English questions into the Prolog subset of logic. The resulting logical expression is then transformed by a planning algorithm into efficient Prolog, cf. query optimisation in a relational database. Finally, the Prolog form is executed to yield the answer. On a domain of world geography, most questions within the English subset are answered in well under one second, including relatively complex queries.