An english generator for a case-labelled dependency representation

Abstract

The paper describes a program which has been constructed to produce English strings from a case-labelled dependency representation. The program uses an especially simple and uniform control structure with a well defined separation of the different knowledge sources used during generation. Furthermore, the majority of the system's knowledge is expressed in a declarative form, so in priciple the generator's knowledge bases could be used for purposes other than generation. The generator uses a two-pass control structure, the first translating from the semantically orientated case-labelled dependency structures into surface syntactic trees and the second translating from these trees into English strings. The generator is very flexible: it can be run in such a way as to produce a ll the possible syntactically legitimate variations on a given utterance, and has built in facilities to do some synonym substitution. It has been used in a number of application domains notably as a part of a free text retrieval system and as part of a natural language front end to a relational database system.