Book Image

Deep Reinforcement Learning Hands-On - Second Edition

By : Maxim Lapan
5 (2)
Book Image

Deep Reinforcement Learning Hands-On - Second Edition

5 (2)
By: Maxim Lapan

Overview of this book

Deep Reinforcement Learning Hands-On, Second Edition is an updated and expanded version of the bestselling guide to the very latest reinforcement learning (RL) tools and techniques. It provides you with an introduction to the fundamentals of RL, along with the hands-on ability to code intelligent learning agents to perform a range of practical tasks. With six new chapters devoted to a variety of up-to-the-minute developments in RL, including discrete optimization (solving the Rubik's Cube), multi-agent methods, Microsoft's TextWorld environment, advanced exploration techniques, and more, you will come away from this book with a deep understanding of the latest innovations in this emerging field. In addition, you will gain actionable insights into such topic areas as deep Q-networks, policy gradient methods, continuous control problems, and highly scalable, non-gradient methods. You will also discover how to build a real hardware robot trained with RL for less than $100 and solve the Pong environment in just 30 minutes of training using step-by-step code optimization. In short, Deep Reinforcement Learning Hands-On, Second Edition, is your companion to navigating the exciting complexities of RL as it helps you attain experience and knowledge through real-world examples.
Table of Contents (28 chapters)
26
Other Books You May Enjoy
27
Index

Actor-critic

The next step in reducing the variance is making our baseline state-dependent (which is a good idea, as different states could have very different baselines). Indeed, to decide on the suitability of a particular action in some state, we use the discounted total reward of the action. However, the total reward itself could be represented as a value of the state plus the advantage of the action: Q(s, a) = V(s) + A(s, a). You saw this in Chapter 8, DQN Extensions, when we discussed DQN modifications, particularly dueling DQN.

So, why can't we use V(s) as a baseline? In that case, the scale of our gradient will be just advantage, A(s, a), showing how this taken action is better in respect to the average state's value. In fact, we can do this, and it is a very good idea for improving the policy gradient method. The only problem here is that we don't know the value, V(s), of the state that we need to subtract from the discounted total reward, Q(s, a). To solve...