WECHSEL: Effective initialization of subword embeddings for cross-lingual transfer of monolingual language models
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Abstract (arXiv)
Large pretrained language models (LMs) have become the central building block of many NLP applications. Training these models requires ever more computational resources and most of the existing models are trained on English text only. It is exceedingly expensive to train these models in other languages. To alleviate this problem, we introduce a novel method -- called WECHSEL -- to efficiently and effectively transfer pretrained LMs to new languages. WECHSEL can be applied to any model which uses subword-based tokenization and learns an embedding for each subword. The tokenizer of the source model (in English) is replaced with a tokenizer in the target language and token embeddings are initialized such that they are semantically similar to the English tokens by utilizing multilingual static word embeddings covering English and the target language. We use WECHSEL to transfer the English RoBERTa and GPT-2 models to four languages (French, German, Chinese and Swahili). We also study the benefits of our method on very low-resource languages. WECHSEL improves over proposed methods for cross-lingual parameter transfer and outperforms models of comparable size trained from scratch with up to 64x less training effort. Our method makes training large language models for new languages more accessible and less damaging to the environment. We make our code and models publicly available.
Key facts. Cited by 89 papers in the map (data through 14 Oct 2026). Builds on 36 of its 63 references that are in the map. First posted on arXiv 13 Dec 2021.
Builds on
36 of 63 references.
References · 36
- 2017Attention Is All You Needcited by 60,361
- 2018BERT: Pre-training of Deep Bidirectional Transformers for Language Understandingcited by 40,399
- 2020Language Models are Few-Shot Learnerscited by 32,419
- 2019RoBERTa: A Robustly Optimized BERT Pretraining Approachcited by 13,372
- 2019Unsupervised Cross-lingual Representation Learning at Scalecited by 3,935
- 2021Switch Transformers: Scaling to Trillion Parameter Models with Simple and Efficient Sparsitycited by 3,073
- 2019XLNet: Generalized Autoregressive Pretraining for Language Understandingcited by 2,811
- 2020mT5: A massively multilingual pre-trained text-to-text transformercited by 1,818
- 2016Enriching Word Vectors with Subword Informationcited by 1,583
- 2016Man is to Computer Programmer as Woman is to Homemaker? Debiasing Word Embeddingscited by 1,312
- 2019Energy and Policy Considerations for Deep Learning in NLPcited by 1,254
- 2018XNLI: Evaluating Cross-lingual Sentence Representationscited by 915
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- 2019SpanBERT: Improving Pre-training by Representing and Predicting Spanscited by 834
- 2019How multilingual is Multilingual BERT?cited by 645
- 2019On the Cross-lingual Transferability of Monolingual Representationscited by 578
- 2017Word Translation Without Parallel Datacited by 487
- 2019CamemBERT: a Tasty French Language Modelcited by 368
- 2020AraBERT: Transformer-based Model for Arabic Language Understandingcited by 362
- 2020How Good is Your Tokenizer? On the Monolingual Performance of Multilingual Language Modelscited by 318
- 2020Are All Languages Created Equal in Multilingual BERT?cited by 207
- 2016Transfer Learning for Low-Resource Neural Machine Translationcited by 188
- 2018Adversarial Removal of Demographic Attributes from Text Datacited by 170
- 2018A robust self-learning method for fully unsupervised cross-lingual mappings of word embeddingscited by 146
- 2020German's Next Language Modelcited by 144
- 2020Pre-training via Paraphrasingcited by 92
- 2018Loss in Translation: Learning Bilingual Word Mapping with a Retrieval Criterioncited by 70
- 2021Few-Shot Question Answering by Pretraining Span Selectioncited by 62
- 2017Transfer Learning across Low-Resource, Related Languages for Neural Machine Translationcited by 58
- 2020As Good as New. How to Successfully Recycle English GPT-2 to Make Models for Other Languagescited by 54
- 2020What the [MASK]? Making Sense of Language-Specific BERT Modelscited by 44
- 2020From English To Foreign Languages: Transferring Pre-trained Language Modelscited by 37
- 2021Societal Biases in Retrieved Contents: Measurement Framework and Adversarial Mitigation for BERT Rankerscited by 35
- 2020Do Neural Ranking Models Intensify Gender Bias?cited by 29
- 2016Learning Crosslingual Word Embeddings without Bilingual Corporacited by 12
- 2019Regularization Advantages of Multilingual Neural Language Models for Low Resource Domainscited by 1
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