Book Image

Advanced Deep Learning with TensorFlow 2 and Keras - Second Edition

By : Rowel Atienza
Book Image

Advanced Deep Learning with TensorFlow 2 and Keras - Second Edition

By: Rowel Atienza

Overview of this book

Advanced Deep Learning with TensorFlow 2 and Keras, Second Edition is a completely updated edition of the bestselling guide to the advanced deep learning techniques available today. Revised for TensorFlow 2.x, this edition introduces you to the practical side of deep learning with new chapters on unsupervised learning using mutual information, object detection (SSD), and semantic segmentation (FCN and PSPNet), further allowing you to create your own cutting-edge AI projects. Using Keras as an open-source deep learning library, the book features hands-on projects that show you how to create more effective AI with the most up-to-date techniques. Starting with an overview of multi-layer perceptrons (MLPs), convolutional neural networks (CNNs), and recurrent neural networks (RNNs), the book then introduces more cutting-edge techniques as you explore deep neural network architectures, including ResNet and DenseNet, and how to create autoencoders. You will then learn about GANs, and how they can unlock new levels of AI performance. Next, you’ll discover how a variational autoencoder (VAE) is implemented, and how GANs and VAEs have the generative power to synthesize data that can be extremely convincing to humans. You'll also learn to implement DRL such as Deep Q-Learning and Policy Gradient Methods, which are critical to many modern results in AI.
Table of Contents (16 chapters)
14
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15
Index

Policy Gradient Methods

In this chapter, we're going to introduce algorithms that directly optimize the policy network in reinforcement learning. These algorithms are collectively referred to as policy gradient methods. Since the policy network is directly optimized during training, the policy gradient methods belong to the family of on-policy reinforcement learning algorithms. Like value-based methods, which we discussed in Chapter 9, Deep Reinforcement Learning, policy gradient methods can also be implemented as deep reinforcement learning algorithms.

A fundamental motivation in studying the policy gradient methods is addressing the limitations of Q-learning. We'll recall that Q-learning is about selecting the action that maximizes the value of the state. With the Q function, we're able to determine the policy that enables the agent to decide on which action to take for a given state. The chosen action is simply the one that gives the agent the maximum...