Learning principled bilingual mappings of word embeddings while preserving monolingual invariance
Written for the Research library (claude-opus-5-5) from the paper text. Original — aclanthology.org/D16-1250.pdf
Summary
The paper addresses cross-lingual word embedding mapping: learning a linear transformation that maps independently trained source-language vectors into a target-language space, using a bilingual dictionary as supervision. Artetxe, Labaka and Agirre start from the least-squares objective of Mikolov et al. (2013b). They then add three constraints: an orthogonal mapping, length normalization, and dimension-wise mean centering. Orthogonality keeps dot products unchanged, so the source space stays intact for monolingual tasks. The resulting framework yields an exact, SVD-based closed-form solution instead of gradient descent. It also reframes earlier methods. Xing et al. (2015) amounts to an orthogonal mapping on unit-length vectors. Faruqui and Dyer's CCA approach is close to the full model but also forces dimensions to be uncorrelated with equal variance. The authors evaluate English–Italian translation induction and the English word analogy task. The full configuration achieves the best translation accuracy while leaving analogy performance almost unchanged. This shows that orthogonality, more than normalization, drives the improvements.
Key points
- Data: The Dinu et al. (2015) English–Italian dataset provides 300-dimensional word2vec CBOW embeddings. English vectors come from ukWaC + Wikipedia + BNC (2.8B words) and Italian vectors from itWaC (1.6B words). It includes a Europarl-derived dictionary with 5,000 training pairs and 1,500 test pairs.
- Translation induction (EN-IT accuracy):
- Mikolov et al. (2013b): 34.93%
- Xing et al. (2015): 36.87%
- Faruqui and Dyer (2014), CCA with 180 dimensions: 37.80%
- Proposed method (orthogonal + length normalization + mean centering): 39.27%
- Monolingual analogy (Mikolov et al. 2013a questions, 30,000-word vocabulary threshold): The original embeddings score 76.66%. The proposed method loses only 0.07 points, compared with 2.86 for Mikolov et al. and 7.02 for CCA.
- Exact solution: The optimal orthogonal mapping is W = VUᵀ, obtained from the SVD of ZᵀX. Its cost grows linearly with vocabulary size.
- Code: The open-source Python/NumPy implementation is released as vecmap (github.com/artetxem/vecmap).
Cited by
- Adversarial Multitask Learning for Joint Multi-Feature and Multi-Dialect Morphological Modeling
- Learning bilingual word embeddings with (almost) no bilingual data
- Unsupervised Neural Machine Translation
- A robust self-learning method for fully unsupervised cross-lingual mappings of word embeddings
- Loss in Translation: Learning Bilingual Word Mapping with a Retrieval Criterion
- Offline bilingual word vectors, orthogonal transformations and the inverted softmax
Cite
@inproceedings{artetxe2016learning,
title = {{Learning principled bilingual mappings of word embeddings while preserving monolingual invariance}},
author = {Artetxe, Mikel and Labaka, Gorka and Agirre, Eneko},
booktitle = {Proceedings of the 2016 Conference on Empirical Methods in Natural Language Processing},
year = {2016},
doi = {10.18653/v1/d16-1250},
url = {https://doi.org/10.18653/v1/d16-1250}
}References
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