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

3. REINFORCE with baseline method

The REINFORCE algorithm can be generalized by subtracting a baseline from the return, . The baseline function, , can be any function as long as it does not depend on . The baseline does not alter the expectation of the performance gradient:

(Equation 10.3.1)

Equation 10.3.1 implies that since is not a function of . While the introduction of a baseline does not change the expectation, it reduces the variance of the gradient updates. The reduction in variance generally accelerates learning.

In most cases, we use the value function, as the baseline. If the return is overestimated, the scaling factor is proportionally reduced by the value function, resulting in a lower variance. The value function is also parameterized, , and is jointly trained with the policy network. In continuous action spaces, the state value can be a linear function of state features:

(Equation 10.3.2)

Algorithm 10.3.1 summarizes the REINFORCE...