Peer reviewed
BERT: Pre-training of Deep Bidirectional Transformers
BERT pre-trains an encoder by masking random tokens and predicting them from both left and right context, unlike the left-to-right models of the GPT line, plus a next-sentence-prediction objective. The resulting representations condition each token on the full surrounding sentence, and a single added output layer fine-tunes the model for classification, tagging, or span-based question answering. It set new results on GLUE and SQuAD and became the standard encoder for understanding-oriented NLP tasks.