Cross-Lingual Word Embedding Refinement by 1 Norm Optimisation

Xutan Peng, Chenghua Lin, Mark Stevenson


Abstract
Cross-Lingual Word Embeddings (CLWEs) encode words from two or more languages in a shared high-dimensional space in which vectors representing words with similar meaning (regardless of language) are closely located. Existing methods for building high-quality CLWEs learn mappings that minimise the ℓ2 norm loss function. However, this optimisation objective has been demonstrated to be sensitive to outliers. Based on the more robust Manhattan norm (aka. ℓ1 norm) goodness-of-fit criterion, this paper proposes a simple post-processing step to improve CLWEs. An advantage of this approach is that it is fully agnostic to the training process of the original CLWEs and can therefore be applied widely. Extensive experiments are performed involving ten diverse languages and embeddings trained on different corpora. Evaluation results based on bilingual lexicon induction and cross-lingual transfer for natural language inference tasks show that the ℓ1 refinement substantially outperforms four state-of-the-art baselines in both supervised and unsupervised settings. It is therefore recommended that this strategy be adopted as a standard for CLWE methods.
Anthology ID:
2021.naacl-main.214
Volume:
Proceedings of the 2021 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies
Month:
June
Year:
2021
Address:
Online
Venue:
NAACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
2690–2701
Language:
URL:
https://aclanthology.org/2021.naacl-main.214
DOI:
10.18653/v1/2021.naacl-main.214
Bibkey:
Cite (ACL):
Xutan Peng, Chenghua Lin, and Mark Stevenson. 2021. Cross-Lingual Word Embedding Refinement by ℓ1 Norm Optimisation Norm Optimisation. In Proceedings of the 2021 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies, pages 2690–2701, Online. Association for Computational Linguistics.
Cite (Informal):
Cross-Lingual Word Embedding Refinement by ℓ1 Norm Optimisation Norm Optimisation (Peng et al., NAACL 2021)
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PDF:
https://preview.aclanthology.org/emnlp-22-attachments/2021.naacl-main.214.pdf
Video:
 https://preview.aclanthology.org/emnlp-22-attachments/2021.naacl-main.214.mp4
Code
 Pzoom522/L1-Refinement