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

5. Temporal-difference learning

Q-learning is a special case of a more generalized TD learning, . More specifically, it is a special case of one-step TD learning, TD(0):

(Equation 9.5.1)

Where is the learning rate. Note that when , Equation 9.5.1 is similar to the Bellman equation. For simplicity, we also refer to Equation 9.5.1 as Q-learning, or generalized Q-learning.

Previously, we referred to Q-learning as an off-policy RL algorithm since it learns the Q value function without directly using the policy that it is trying to optimize. An example of an on-policy one-step TD-learning algorithm is SARSA, which is similar to Equation 9.5.1:

(Equation 9.5.2)

The main difference is the use of the policy that is being optimized to determine . The terms , , , , and (thus the name SARSA) must be known to update the Q value function every iteration. Both Q-learning and SARSA use existing estimates in the Q value iteration, a process known as bootstrapping...