The Derivation of a Grammatically Indexed Lexicon from the Longman Dictionary of Contemporary English

The Derivation of a GrammaticaUy Indexed Lexicon from the Longman Dictionary of Contemporary English Bran Boguraev t, Ted Briscoe§, John Carroll t, David Carter t and Claire Grover§ t Computer Laboratory, Universityof Cambridge Corn Exchange Street, Cambridge CB2 3QG, England § Department of Linguistics, University of Lancaster Bailrigg, Lancaster LA1 4YT, England Abstract We describe a methodology and associated software system for the construction of a large lexicon from an existing machine-readable (published) dictionary. The lexicon serves as a component of an English mor- phological and syntactic analyesr and contains entries with grammatical definitions compatible with the word and sentence grammar employed by the analyser. We describe a software system with two integrated com- ponents. One of these is capable of extracting syn- tactically rich, theory-neutral lexical templates from a suitable machine-readabh source. The second sup- ports interactive and semi-automatic generation and testing of target lexical entries in order to derive a size- able, accurate and consistent lexicon from the source dictionary which contains partial (and occasionally in- accurate) information. Finally, we evaluate the utility of the Longman Dictionary of Contemporary EnglgsA as a suitable source dictionary for the target lexicon. 1 Introduction Within the larger framework of the Alvey Programme of advanced information technology -- a research and development initiative set up in the UK to promote collaborative research projects ~imed at several en- abling key technologies -- a coordinated e~ort to build a natural language toolkit for the use by the wider aca- demic and industrial community is being carried out jointly by groups at the Universities of Cambridge, Lancaster and Edinburgh. The goal of these three closely related projects is to produce directly compatible rule systems and associ- ated software, capable of functioning together as an in- tegrated system for morphological and syntactic pars- ing of texts. The projects aim to deliver, respectively, a 8entente grammar of English together with a toord list indexed to the grammar, a combined inflectional and derlvational morphological ana/y~er and dictionary 8~s- tent, and a parser for the grammatical formalism used. The work is being carried out within the theoretical framework of Generalized Phrase Structure Grammar (Gszdar et ai., 1985), but many of the mechanisms would be usable without a theoretical commitment to GPSG. It is envisaged that the complete integrated toolkit will be used by a number of research and de- velopment groups, as a base component for a range of applications. The potential requirements of a diverse user community motivate, in particular, the need for a morphological and syntactic anaiyser with wide cov- erage of English grammar and vocabulary. Briscoe et al. (1987) describes the sentence grammar formalism and current coverage of the English grammar in detail. Russell et al. (1986) describes the morphological anal- yser and dictionary system. Further relevant details of both projects are provided in section 2. As part of the grammar project, in tandem with the development of the grammar proper, work is un- derway to develop a sizeable word list which will be in- tegrated …

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