Overcoming the Rare Word Problem for low-resource language pairs in Neural Machine Translation

Thi-Vinh Ngo, Thanh-Le Ha, Phuong-Thai Nguyen, Le-Minh Nguyen


Abstract
Among the six challenges of neural machine translation (NMT) coined by (Koehn and Knowles, 2017), rare-word problem is considered the most severe one, especially in translation of low-resource languages. In this paper, we propose three solutions to address the rare words in neural machine translation systems. First, we enhance source context to predict the target words by connecting directly the source embeddings to the output of the attention component in NMT. Second, we propose an algorithm to learn morphology of unknown words for English in supervised way in order to minimize the adverse effect of rare-word problem. Finally, we exploit synonymous relation from the WordNet to overcome out-of-vocabulary (OOV) problem of NMT. We evaluate our approaches on two low-resource language pairs: English-Vietnamese and Japanese-Vietnamese. In our experiments, we have achieved significant improvements of up to roughly +1.0 BLEU points in both language pairs.
Anthology ID:
D19-5228
Volume:
Proceedings of the 6th Workshop on Asian Translation
Month:
November
Year:
2019
Address:
Hong Kong, China
Editors:
Toshiaki Nakazawa, Chenchen Ding, Raj Dabre, Anoop Kunchukuttan, Nobushige Doi, Yusuke Oda, Ondřej Bojar, Shantipriya Parida, Isao Goto, Hidaya Mino
Venue:
WAT
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
207–214
Language:
URL:
https://aclanthology.org/D19-5228
DOI:
10.18653/v1/D19-5228
Bibkey:
Cite (ACL):
Thi-Vinh Ngo, Thanh-Le Ha, Phuong-Thai Nguyen, and Le-Minh Nguyen. 2019. Overcoming the Rare Word Problem for low-resource language pairs in Neural Machine Translation. In Proceedings of the 6th Workshop on Asian Translation, pages 207–214, Hong Kong, China. Association for Computational Linguistics.
Cite (Informal):
Overcoming the Rare Word Problem for low-resource language pairs in Neural Machine Translation (Ngo et al., WAT 2019)
Copy Citation:
PDF:
https://aclanthology.org/D19-5228.pdf