diff --git a/README.md b/README.md new file mode 100644 index 0000000..9c05e78 --- /dev/null +++ b/README.md @@ -0,0 +1,126 @@ +--- +language: en +license: apache-2.0 +datasets: +- bookcorpus +- wikipedia +--- + +# BERT large model (uncased) whole word masking finetuned on SQuAD + +Pretrained model on English language using a masked language modeling (MLM) objective. It was introduced in +[this paper](https://arxiv.org/abs/1810.04805) and first released in +[this repository](https://github.com/google-research/bert). This model is uncased: it does not make a difference +between english and English. + +Differently to other BERT models, this model was trained with a new technique: Whole Word Masking. In this case, all of the tokens corresponding to a word are masked at once. The overall masking rate remains the same. + +The training is identical -- each masked WordPiece token is predicted independently. + +After pre-training, this model was fine-tuned on the SQuAD dataset with one of our fine-tuning scripts. See below for more information regarding this fine-tuning. + +Disclaimer: The team releasing BERT did not write a model card for this model so this model card has been written by +the Hugging Face team. + +## Model description + +BERT is a transformers model pretrained on a large corpus of English data in a self-supervised fashion. This means it +was pretrained on the raw texts only, with no humans labelling them in any way (which is why it can use lots of +publicly available data) with an automatic process to generate inputs and labels from those texts. More precisely, it +was pretrained with two objectives: + +- Masked language modeling (MLM): taking a sentence, the model randomly masks 15% of the words in the input then run + the entire masked sentence through the model and has to predict the masked words. This is different from traditional + recurrent neural networks (RNNs) that usually see the words one after the other, or from autoregressive models like + GPT which internally mask the future tokens. It allows the model to learn a bidirectional representation of the + sentence. +- Next sentence prediction (NSP): the models concatenates two masked sentences as inputs during pretraining. Sometimes + they correspond to sentences that were next to each other in the original text, sometimes not. The model then has to + predict if the two sentences were following each other or not. + +This way, the model learns an inner representation of the English language that can then be used to extract features +useful for downstream tasks: if you have a dataset of labeled sentences for instance, you can train a standard +classifier using the features produced by the BERT model as inputs. + +## Intended uses & limitations +This model should be used as a question-answering model. You may use it in a question answering pipeline, or use it to output raw results given a query and a context. You may see other use cases in the [task summary](https://huggingface.co/transformers/task_summary.html#extractive-question-answering) of the transformers documentation.## Training data + +The BERT model was pretrained on [BookCorpus](https://yknzhu.wixsite.com/mbweb), a dataset consisting of 11,038 +unpublished books and [English Wikipedia](https://en.wikipedia.org/wiki/English_Wikipedia) (excluding lists, tables and +headers). + +## Training procedure + +### Preprocessing + +The texts are lowercased and tokenized using WordPiece and a vocabulary size of 30,000. The inputs of the model are +then of the form: + +``` +[CLS] Sentence A [SEP] Sentence B [SEP] +``` + +With probability 0.5, sentence A and sentence B correspond to two consecutive sentences in the original corpus and in +the other cases, it's another random sentence in the corpus. Note that what is considered a sentence here is a +consecutive span of text usually longer than a single sentence. The only constrain is that the result with the two +"sentences" has a combined length of less than 512 tokens. + +The details of the masking procedure for each sentence are the following: +- 15% of the tokens are masked. +- In 80% of the cases, the masked tokens are replaced by `[MASK]`. +- In 10% of the cases, the masked tokens are replaced by a random token (different) from the one they replace. +- In the 10% remaining cases, the masked tokens are left as is. + +### Pretraining + +The model was trained on 4 cloud TPUs in Pod configuration (16 TPU chips total) for one million steps with a batch size +of 256. The sequence length was limited to 128 tokens for 90% of the steps and 512 for the remaining 10%. The optimizer +used is Adam with a learning rate of 1e-4, \\(\beta_{1} = 0.9\\) and \\(\beta_{2} = 0.999\\), a weight decay of 0.01, +learning rate warmup for 10,000 steps and linear decay of the learning rate after. +### Fine-tuningAfter pre-training, this model was fine-tuned on the SQuAD dataset with one of our fine-tuning scripts. In order to reproduce the training, you may use the following command: +``` +python -m torch.distributed.launch --nproc_per_node=8 ./examples/question-answering/run_qa.py \ + --model_name_or_path bert-large-uncased-whole-word-masking \ + --dataset_name squad \ + --do_train \ + --do_eval \ + --learning_rate 3e-5 \ + --num_train_epochs 2 \ + --max_seq_length 384 \ + --doc_stride 128 \ + --output_dir ./examples/models/wwm_uncased_finetuned_squad/ \ + --per_device_eval_batch_size=3 \ + --per_device_train_batch_size=3 \ +``` + +## Evaluation results + +The results obtained are the following: + +``` +f1 = 93.15 +exact_match = 86.91 +``` + + +### BibTeX entry and citation info + +```bibtex +@article{DBLP:journals/corr/abs-1810-04805, + author = {Jacob Devlin and + Ming{-}Wei Chang and + Kenton Lee and + Kristina Toutanova}, + title = {{BERT:} Pre-training of Deep Bidirectional Transformers for Language + Understanding}, + journal = {CoRR}, + volume = {abs/1810.04805}, + year = {2018}, + url = {http://arxiv.org/abs/1810.04805}, + archivePrefix = {arXiv}, + eprint = {1810.04805}, + timestamp = {Tue, 30 Oct 2018 20:39:56 +0100}, + biburl = {https://dblp.org/rec/journals/corr/abs-1810-04805.bib}, + bibsource = {dblp computer science bibliography, https://dblp.org} +} +``` \ No newline at end of file