ACTA UNIVERSITATIS UPSALIENSIS
Studia Linguistica Upsaliensia
1

Recycling Translations

Extraction of Lexical Data from Parallel Corpora and their Application in Natural Language Processing

BY

JÖRG TIEDEMANN

ACTA UNIVERSITATIS UPSALIENSIS
UPPSALA 2003

Abstract:

Dissertation at Uppsala University to be publicly examined in the lecture hall IX, University Hall, Friday, December 12, 2003 at 10:15 for the Degree of Doctor of Philosophy. The examination will be conducted in English

Abstract Tiedemann, J. 2003. Recycling Translations. Extraction of Lexical Data from Parallel Corpora and their Application in Natural Language Processing. Acta Universitatis Upsaliensis. Studia Linguistica Upsaliensia 1. 130 pp. Uppsala. ISBN 91-554-5815-7

The focus of this thesis is on re-using translations in natural language processing. It involves the collection of documents and their translations in an appropriate format, the automatic extraction of translation data, and the application of the extracted data to different tasks in natural language processing. Five parallel corpora containing more than 35 million words in 60 languages have been collected within co-operative projects. All corpora are sentence aligned and parts of them have been analyzed automatically and annotated with linguistic markup. Lexical data are extracted from the corpora by means of word alignment. Two automatic word alignment systems have been developed, the Uppsala Word Aligner (UWA) and the Clue Aligner. UWA implements an iterative ''knowledge-poor'' word alignment approach using association measures and alignment heuristics. The Clue Aligner provides an innovative framework for the combination of statistical and linguistic resources in aligning single words and multi-word units. Both aligners have been applied to several corpora. Detailed evaluations of the alignment results have been carried out for three of them using fine-grained evaluation techniques. A corpus processing toolbox, Uplug, has been developed. It includes the implementation of UWA and is freely available for research purposes. A new version, Uplug II, includes the Clue Aligner. It can be used via an experimental web interface (UplugWeb). Lexical data extracted by the word aligners have been applied to different tasks in computational lexicography and machine translation. The use of word alignment in monolingual lexicography has been investigated in two studies. In a third study, the feasibility of using the extracted data in interactive machine translation has been demonstrated. Finally, extracted lexical data have been used for enhancing the lexical components of two machine translation systems.

Keywords: word alignment, parallel corpora, translation corpora, computational lexicography, machine translation, computational linguistics

Jörg Tiedemann, Department of Linguistics. Uppsala University. Villavägen 4, Box 527, 751 20 Uppsala

© Jörg Tiedemann 2003

ISBN 91-554-5815-7 ISSN 1652-1366 urn:nbn:se:uu:diva-3791 (http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3791)