XLM-V: Overcoming the Vocabulary Bottleneck in Multilingual Masked Language Models
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Abstract (arXiv)
Large multilingual language models typically rely on a single vocabulary shared across 100+ languages. As these models have increased in parameter count and depth, vocabulary size has remained largely unchanged. This textitvocabulary bottleneck limits the representational capabilities of multilingual models like XLM-R. In this paper, we introduce a new approach for scaling to very large multilingual vocabularies by de-emphasizing token sharing between languages with little lexical overlap and assigning vocabulary capacity to achieve sufficient coverage for each individual language. Tokenizations using our vocabulary are typically more semantically meaningful and shorter compared to XLM-R. Leveraging this improved vocabulary, we train XLM-V, a multilingual language model with a one million token vocabulary. XLM-V outperforms XLM-R on every task we tested on ranging from natural language inference (XNLI), question answering (MLQA, XQuAD, TyDiQA), to named entity recognition (WikiAnn). XLM-V is particularly effective on low-resource language tasks and outperforms XLM-R by 11.2% and 5.8% absolute on MasakhaNER and Americas NLI, respectively.
Key facts. Cited by 88 papers in the map (data through 7 Oct 2026). Builds on 28 of its 37 references that are in the map. First posted on arXiv 25 Jan 2023.
Builds on
28 of 37 references.
References · 28
- 2018BERT: Pre-training of Deep Bidirectional Transformers for Language Understandingcited by 40,204
- 2014Adam: A Method for Stochastic Optimizationcited by 36,960
- 2016SQuAD: 100,000+ Questions for Machine Comprehension of Textcited by 4,115
- 2019Unsupervised Cross-lingual Representation Learning at Scalecited by 3,907
- 2018SentencePiece: A simple and language independent subword tokenizer and detokenizer for Neural Text Processingcited by 1,973
- 2022BLOOM: A 176B-Parameter Open-Access Multilingual Language Modelcited by 1,968
- 2020mT5: A massively multilingual pre-trained text-to-text transformercited by 1,813
- 2019fairseq: A Fast, Extensible Toolkit for Sequence Modelingcited by 1,486
- 2019Cross-lingual Language Model Pretrainingcited by 1,088
- 2020Multilingual Denoising Pre-training for Neural Machine Translationcited by 1,028
- 2018XNLI: Evaluating Cross-lingual Sentence Representationscited by 913
- 2020XTREME: A Massively Multilingual Multi-task Benchmark for Evaluating Cross-lingual Generalizationcited by 738
16 more
- 2019On the Cross-lingual Transferability of Monolingual Representationscited by 575
- 2021The FLORES-101 Evaluation Benchmark for Low-Resource and Multilingual Machine Translationcited by 556
- 2021ByT5: Towards a token-free future with pre-trained byte-to-byte modelscited by 504
- 2020TyDi QA: A Benchmark for Information-Seeking Question Answering in Typologically Diverse Languagescited by 486
- 2019MLQA: Evaluating Cross-lingual Extractive Question Answeringcited by 339
- 2020How Good is Your Tokenizer? On the Monolingual Performance of Multilingual Language Modelscited by 313
- 2021CANINE: Pre-training an Efficient Tokenization-Free Encoder for Language Representationcited by 229
- 2018Adaptive Input Representations for Neural Language Modelingcited by 226
- 2015Conditional Computation in Neural Networks for faster modelscited by 166
- 2021MasakhaNER: Named Entity Recognition for African Languagescited by 155
- 2021Larger-Scale Transformers for Multilingual Masked Language Modelingcited by 86
- 2016Efficient softmax approximation for GPUscited by 67
- 2020Improving Multilingual Models with Language-Clustered Vocabulariescited by 53
- 2021AmericasNLI: Evaluating Zero-shot Natural Language Understanding of Pretrained Multilingual Models in Truly Low-resource Languagescited by 50
- 2019Improving Pre-Trained Multilingual Models with Vocabulary Expansioncited by 27
- 2021Allocating Large Vocabulary Capacity for Cross-lingual Language Model Pre-trainingcited by 22
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Citing papers per year: 2023: 20; 2024: 32; 2025: 25; 2026: 11.
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