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

Understanding the encoder of the transformer

The transformer consists of a stack of number of encoders. The output of one encoder is sent as input to the encoder above it. As shown in the following figure, we have a stack of number of encoders. Each encoder sends its output to the encoder above it. The final encoder returns the representation of the given source sentence as output. We feed the source sentence as input to the encoder and get the representation of the source sentence as output:

Figure 1.2 – A stack of N number of encoders

Note that in the transformer paper Attention Is All You Need, the authors have used , meaning that they stacked up six encoders one above the another. However, we can try out different values of . For simplicity and better understanding, let's keep :

Figure 1.3 – A stack of encoders

Okay, the question is how exactly does the encoder work? How is it generating the representation for the given source sentence (input sentence)...