Book Image

Deep Reinforcement Learning Hands-On

By : Maxim Lapan
Book Image

Deep Reinforcement Learning Hands-On

By: Maxim Lapan

Overview of this book

Deep Reinforcement Learning Hands-On is a comprehensive guide to the very latest DL tools and their limitations. You will evaluate methods including Cross-entropy and policy gradients, before applying them to real-world environments. Take on both the Atari set of virtual games and family favorites such as Connect4. The book provides an introduction to the basics of RL, giving you the know-how to code intelligent learning agents to take on a formidable array of practical tasks. Discover how to implement Q-learning on 'grid world' environments, teach your agent to buy and trade stocks, and find out how natural language models are driving the boom in chatbots.
Table of Contents (23 chapters)
Deep Reinforcement Learning Hands-On
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Practical cross-entropy

The cross-entropy method description is split into two unequal parts: practical and theoretical. The practical part is intuitive in its nature, while the theoretical explanation of why cross-entropy works, and what's happening is more sophisticated.

You may remember that the central, trickiest thing in RL is the agent, which is trying to accumulate as much total reward as possible by communicating with the environment. In practice, we follow a common ML approach and replace all of the complications of the agent with some kind of nonlinear trainable function, which maps the agent's input (observations from the environment) to some output. The details of the output that this function produces may depend on a particular method or a family of methods, as described in the previous section (such as value-based versus policy-based methods). As our cross-entropy method is policy-based, our nonlinear function (neural network) produces policy, which basically says for every...