Book Image

Transformers for Natural Language Processing

By : Denis Rothman
Book Image

Transformers for Natural Language Processing

By: Denis Rothman

Overview of this book

The transformer architecture has proved to be revolutionary in outperforming the classical RNN and CNN models in use today. With an apply-as-you-learn approach, Transformers for Natural Language Processing investigates in vast detail the deep learning for machine translations, speech-to-text, text-to-speech, language modeling, question answering, and many more NLP domains with transformers. The book takes you through NLP with Python and examines various eminent models and datasets within the transformer architecture created by pioneers such as Google, Facebook, Microsoft, OpenAI, and Hugging Face. The book trains you in three stages. The first stage introduces you to transformer architectures, starting with the original transformer, before moving on to RoBERTa, BERT, and DistilBERT models. You will discover training methods for smaller transformers that can outperform GPT-3 in some cases. In the second stage, you will apply transformers for Natural Language Understanding (NLU) and Natural Language Generation (NLG). Finally, the third stage will help you grasp advanced language understanding techniques such as optimizing social network datasets and fake news identification. By the end of this NLP book, you will understand transformers from a cognitive science perspective and be proficient in applying pretrained transformer models by tech giants to various datasets.
Table of Contents (16 chapters)
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What this book covers

Part I: Introduction to Transformer Architectures

Chapter 1, Getting Started with the Model Architecture of the Transformer, goes through the background of NLP to understand how RNN, LSTM, and CNN architectures were abandoned and how the Transformer architecture opened a new era. We will go through the Transformer's architecture through the unique "Attention Is All You Need" approach invented by the Google Research and Google Brain authors. We will describe the theory of transformers. We will get our hands dirty in Python to see how the multi-attention head sub-layers work. By the end of this chapter, you will have understood the original architecture of the Transformer. You will be ready to explore the multiple variants and usages of the Transformer in the following chapters.

Chapter 2, Fine-Tuning BERT Models, builds on the architecture of the original Transformer. Bidirectional Encoder Representations from Transformers (BERT) takes transformers into a vast new way of perceiving the world of NLP. Instead of analyzing a past sequence to predict a future sequence, BERT attends to the whole sequence! We will first go through the key innovations of BERT's architecture and then fine-tune a BERT model by going through each step in a Google Colaboratory notebook. Like humans, BERT can learn tasks and perform other new ones without having to learn the topic from scratch.

Chapter 3, Pretraining a RoBERTa Model from Scratch, builds a RoBERTa transformer model from scratch using the Hugging Face PyTorch modules. The transformer will be both BERT-like and DistilBERT-like. First, we will train a tokenizer from scratch on a customized dataset. The trained transformer will then run on a downstream masked language modeling task.

We will experiment with masked language modeling on an Immanuel Kant dataset to explore conceptual NLP representations.

Part II: Applying Transformers for Natural Language Understanding and Generation

Chapter 4, Downstream NLP Tasks with Transformers, reveals the magic of transformer models with downstream NLP tasks. A pretrained transformer model can be fine-tuned to solve a range of NLP tasks such as BoolQ, CB, MultiRC, RTE, WiC, and more, dominating the GLUE and SuperGLUE leaderboards. We will go through the evaluation process of transformers, the tasks, datasets, and metrics. We will then run some of the downstream tasks with Hugging Face's pipeline of transformers.

Chapter 5, Machine Translation with the Transformer, defines machine translation to understand how to go from human baselines to machine transduction methods. We will then preprocess a WMT French-English dataset from the European Parliament. Machine translation requires precise evaluation methods, and in this chapter, we explore the BLEU scoring method. Finally, we will implement a Transformer machine translation model with Trax.

Chapter 6, Text Generation with OpenAI GPT-2 and GPT-3 Models, explores many aspects of OpenAI's GPT-2 transformers. We will first examine GPT-2 and GPT-3 from a project management perspective by looking into alternative solutions such as the Reformer and PET. Then we will explore the novel architecture of OpenAI's GPT-2 and GPT-3 transformer models and run a GPT-2 345M parameter model and interact with it to generate text. We will then train a GPT-2 117M parameter model on a custom dataset and produce customized text completion.

Chapter 7, Applying Transformers to Legal and Financial Documents for AI Text Summarization, goes through the concepts and architecture of the T5 transformer model. We will initialize a T5 model from Hugging Face to summarize documents. Finally, we will task the T5 model to summarize various documents, including a sample from the Bill of Rights, exploring the successes and limitations of transfer learning approaches applied to transformers.

Chapter 8, Matching Tokenizers and Datasets, analyzes the limits of tokenizers and looks at some of the methods applied to improve the data encoding process's quality. We will first build a Python program to investigate why some words are omitted or misinterpreted by word2vector tokenizers. Following this, we find the limits of pretrained tokenizers with a tokenizer-agonistic method. Finally, we will improve a T5 summary by applying some of the ideas that show that there is still much room left to improve the methodology of the tokenization process.

Chapter 9, Semantic Role Labeling with BERT-Based Transformers, explores how transformers learn to understand a text's content. Semantic Role Labeling (SRL) is a challenging exercise for a human. Transformers can produce surprising results. We will implement a BERT-based transformer model designed by the Allen Institute for AI in a Google Colab notebook. We will also use their online resources to visualize SRL outputs.

Part III: Advanced Language Understanding Techniques

Chapter 10, Let Your Data Do the Talking: Story, Questions, and Answers, shows how a transformer can learn how to reason. A transformer must be able to understand a text, a story, and also display reasoning skills. We will see how question answering can be enhanced by adding NER and SRL to the process. We will build the blueprint for a question generator that can be used to train transformers or as a stand-alone solution.

Chapter 11, Detecting Customer Emotions to Make Predictions, shows how transformers have improved sentiment analysis. We will analyze complex sentences using the Stanford Sentiment Treebank, challenging several transformer models to understand not only the structure of a sequence but also its logical form. We will see how to use transformers to make predictions that trigger different actions depending on the sentiment analysis output.

Chapter 12, Analyzing Fake News with Transformers, delves into the hot topic of fake news and how transformers can help us understand the different perspectives of the online content we see each day. Every day, billions of messages, posts, and articles are published on the web through social media, websites, and every form of real-time communication available. Using several techniques from the previous chapters, we will analyze debates on climate change and gun control and the Tweets from a former president. We will go through the moral and ethical problem of determining what can be considered fake news beyond reasonable doubt and what news remains subjective.