Book Image

Getting Started with Google BERT

By : Sudharsan Ravichandiran
Book Image

Getting Started with Google BERT

By: Sudharsan Ravichandiran

Overview of this book

BERT (bidirectional encoder representations from transformer) has revolutionized the world of natural language processing (NLP) with promising results. This book is an introductory guide that will help you get to grips with Google's BERT architecture. With a detailed explanation of the transformer architecture, this book will help you understand how the transformer’s encoder and decoder work. You’ll explore the BERT architecture by learning how the BERT model is pre-trained and how to use pre-trained BERT for downstream tasks by fine-tuning it for NLP tasks such as sentiment analysis and text summarization with the Hugging Face transformers library. As you advance, you’ll learn about different variants of BERT such as ALBERT, RoBERTa, and ELECTRA, and look at SpanBERT, which is used for NLP tasks like question answering. You'll also cover simpler and faster BERT variants based on knowledge distillation such as DistilBERT and TinyBERT. The book takes you through MBERT, XLM, and XLM-R in detail and then introduces you to sentence-BERT, which is used for obtaining sentence representation. Finally, you'll discover domain-specific BERT models such as BioBERT and ClinicalBERT, and discover an interesting variant called VideoBERT. By the end of this BERT book, you’ll be well-versed with using BERT and its variants for performing practical NLP tasks.
Table of Contents (15 chapters)
1
Section 1 - Starting Off with BERT
5
Section 2 - Exploring BERT Variants
8
Section 3 - Applications of BERT

Chapter 3, Getting Hands-On with BERT

  1. We can use the pre-trained model in the following two ways:
  • As a feature extractor by extracting embeddings
  • By fine-tuning the pre-trained BERT model on downstream tasks such as text classification, question-answering, and more
  1. The [PAD] token is used to match the token length.
  2. To make our model understand that the [PAD] token is added only to match the tokens length and that it is not part of the actual tokens, we use an attention mask. We set the attention mask value to 1 in all positions and 0 for the position where we have the [PAD] token.
  3. Fine-tuning implies that we are not training BERT from scratch; instead, we are using the already-trained BERT and updating its weights according to our task.
  4. For each token , we compute the dot product between the representation of the token and the start vector . Next, we apply the softmax function to the dot product and obtain the probability: . Next, we compute the starting index by selecting...