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

1. Policy gradient theorem

As discussed in Chapter 9, Deep Reinforcement Learning, the agent is situated in an environment that is in state st, an element of state space, . The state space may be discrete or continuous. The agent takes an action from the action space by obeying the policy, . may be discrete or continuous. As a result of executing the action , the agent receives a reward rt+1 and the environment transitions to a new state, st+1. The new state is dependent only on the current state and action. The goal of the agent is to learn an optimal policy that maximizes the return from all states:

(Equation 9.1.1)

The return, Rt, is defined as the discounted cumulative reward from time t until the end of the episode or when the terminal state is reached:

(Equation 9.1.2)

From Equation 9.1.2, the return can also be interpreted as a value of a given state by following the policy . It can be observed from Equation 9.1.1 that future rewards ...