Unsupervised Cross-lingual Representation Learning at Scale (XLM-RoBERTa)

https://arxiv.org/pdf/1911.02116.pdf

Introduction

XLM-R (XLM-RoBERTa) is a generic cross lingual sentence encoder that obtains state-of-the-art results on many cross-lingual understanding (XLU) benchmarks. It is trained on 2.5T of filtered CommonCrawl data in 100 languages (list below).

Language	Language	Language	Language	Language
Afrikaans	Albanian	Amharic	Arabic	Armenian
Assamese	Azerbaijani	Basque	Belarusian	Bengali
Bengali Romanize	Bosnian	Breton	Bulgarian	Burmese
Burmese zawgyi font	Catalan	Chinese (Simplified)	Chinese (Traditional)	Croatian
Czech	Danish	Dutch	English	Esperanto
Estonian	Filipino	Finnish	French	Galician
Georgian	German	Greek	Gujarati	Hausa
Hebrew	Hindi	Hindi Romanize	Hungarian	Icelandic
Indonesian	Irish	Italian	Japanese	Javanese
Kannada	Kazakh	Khmer	Korean	Kurdish (Kurmanji)
Kyrgyz	Lao	Latin	Latvian	Lithuanian
Macedonian	Malagasy	Malay	Malayalam	Marathi
Mongolian	Nepali	Norwegian	Oriya	Oromo
Pashto	Persian	Polish	Portuguese	Punjabi
Romanian	Russian	Sanskrit	Scottish Gaelic	Serbian
Sindhi	Sinhala	Slovak	Slovenian	Somali
Spanish	Sundanese	Swahili	Swedish	Tamil
Tamil Romanize	Telugu	Telugu Romanize	Thai	Turkish
Ukrainian	Urdu	Urdu Romanize	Uyghur	Uzbek
Vietnamese	Welsh	Western Frisian	Xhosa	Yiddish

Pre-trained models

Model	Description	#params	vocab size	Download
`xlmr.base`	XLM-R using the BERT-base architecture	250M	250k	xlm.base.tar.gz
`xlmr.large`	XLM-R using the BERT-large architecture	560M	250k	xlm.large.tar.gz

(Note: Above are final model checkpoints. If you were using previously released v0 version, we recommend using above. They have same architecture and dictionary.)

Results

XNLI (Conneau et al., 2018)

Model	average	en	fr	es	de	el	bg	ru	tr	ar	vi	th	zh	hi	sw	ur
`roberta.large.mnli` (TRANSLATE-TEST)	77.8	91.3	82.9	84.3	81.2	81.7	83.1	78.3	76.8	76.6	74.2	74.1	77.5	70.9	66.7	66.8
`xlmr.large` (TRANSLATE-TRAIN-ALL)	83.6	89.1	85.1	86.6	85.7	85.3	85.9	83.5	83.2	83.1	83.7	81.5	83.7	81.6	78.0	78.1

MLQA (Lewis et al., 2018)

Model	average	en	es	de	ar	hi	vi	zh
`BERT-large`	-	80.2/67.4	-	-	-	-	-	-
`mBERT`	57.7 / 41.6	77.7 / 65.2	64.3 / 46.6	57.9 / 44.3	45.7 / 29.8	43.8 / 29.7	57.1 / 38.6	57.5 / 37.3
`xlmr.large`	70.7 / 52.7	80.6 / 67.8	74.1 / 56.0	68.5 / 53.6	63.1 / 43.5	69.2 / 51.6	71.3 / 50.9	68.0 / 45.4

Example usage

Load XLM-R from torch.hub (PyTorch >= 1.1):

import torch
xlmr = torch.hub.load('pytorch/fairseq', 'xlmr.large')
xlmr.eval()  # disable dropout (or leave in train mode to finetune)

Load XLM-R (for PyTorch 1.0 or custom models):

# Download xlmr.large model
wget https://dl.fbaipublicfiles.com/fairseq/models/xlmr.large.tar.gz
tar -xzvf xlmr.large.tar.gz

# Load the model in fairseq
from fairseq.models.roberta import XLMRModel
xlmr = XLMRModel.from_pretrained('/path/to/xlmr.large', checkpoint_file='model.pt')
xlmr.eval()  # disable dropout (or leave in train mode to finetune)

Apply sentence-piece-model (SPM) encoding to input text:

en_tokens = xlmr.encode('Hello world!')
assert en_tokens.tolist() == [0, 35378,  8999, 38, 2]
xlmr.decode(en_tokens)  # 'Hello world!'

zh_tokens = xlmr.encode('你好，世界')
assert zh_tokens.tolist() == [0, 6, 124084, 4, 3221, 2]
xlmr.decode(zh_tokens)  # '你好，世界'

hi_tokens = xlmr.encode('नमस्ते दुनिया')
assert hi_tokens.tolist() == [0, 68700, 97883, 29405, 2]
xlmr.decode(hi_tokens)  # 'नमस्ते दुनिया'

ar_tokens = xlmr.encode('مرحبا بالعالم')
assert ar_tokens.tolist() == [0, 665, 193478, 258, 1705, 77796, 2]
xlmr.decode(ar_tokens) # 'مرحبا بالعالم'

fr_tokens = xlmr.encode('Bonjour le monde')
assert fr_tokens.tolist() == [0, 84602, 95, 11146, 2]
xlmr.decode(fr_tokens) # 'Bonjour le monde'

Extract features from XLM-R:

# Extract the last layer's features
last_layer_features = xlmr.extract_features(zh_tokens)
assert last_layer_features.size() == torch.Size([1, 6, 1024])

# Extract all layer's features (layer 0 is the embedding layer)
all_layers = xlmr.extract_features(zh_tokens, return_all_hiddens=True)
assert len(all_layers) == 25
assert torch.all(all_layers[-1] == last_layer_features)

Citation

@article{conneau2019unsupervised,
  title={Unsupervised Cross-lingual Representation Learning at Scale},
  author={Conneau, Alexis and Khandelwal, Kartikay and Goyal, Naman and Chaudhary, Vishrav and Wenzek, Guillaume and Guzm{\'a}n, Francisco and Grave, Edouard and Ott, Myle and Zettlemoyer, Luke and Stoyanov, Veselin},
  journal={arXiv preprint arXiv:1911.02116},
  year={2019}
}