Boosting Neural Machine Translation from Finnish to Northern Sámi with Rule-Based Backtranslation

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Abstract

We consider a low-resource translation task from Finnish into Northern Sámi. Collecting all available parallel data between the languages, we obtain around 30,000 sentence pairs. However, there exists a significantly larger monolingual Northern Sámi corpus, as well as a rule-based machine translation (RBMT) system between the languages. To make the best use of the monolingual data in a neural machine translation (NMT) system, we use the backtranslation approach to create synthetic parallel data from it using both NMT and RBMT systems. Evaluating the results on an in-domain test set and a small out-of-domain set, we find that the RBMT backtranslation outperforms NMT backtranslation clearly for the out-of-domain test set, but also slightly for the in-domain data, for which the NMT backtranslation model provided clearly better BLEU scores than the RBMT. In addition, combining both backtranslated data sets improves the RBMT approach only for the in-domain test set. This suggests that the RBMT system provides general-domain knowledge that cannot be found from the relative small parallel training data.
Original languageEnglish
Title of host publicationProceedings of the 23rd Nordic Conference on Computational Linguistics (NoDaLiDa)
EditorsSimon Dobnik, Lilja Øvrelid
Number of pages6
Place of PublicationLinköping
PublisherLinköping University Electronic Press
Publication dateMay 2021
Pages351-356
ISBN (Electronic)978-91-7929-614-8
Publication statusPublished - May 2021
MoE publication typeA4 Article in conference proceedings
EventNordic Conference on Computational Linguistics - [Online event], Reykjavik, Iceland
Duration: 31 May 20212 Jun 2021
Conference number: 23
https://nodalida2021.github.io/index.html

Publication series

NameLinköping Electronic Conference Proceedings
PublisherLinköping University Electronic Press
Number78
ISSN (Print)1650-3740
ISSN (Electronic)1650-3686
NameNEALT Proceedings Series
PublisherUniversity of Tartu
Number45
ISSN (Print)1736-8197
ISSN (Electronic)1736-6305

Fields of Science

  • 6121 Languages
  • 113 Computer and information sciences

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