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Hands-On Q-Learning with Python

You're reading from   Hands-On Q-Learning with Python Practical Q-learning with OpenAI Gym, Keras, and TensorFlow

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Product type Paperback
Published in Apr 2019
Publisher Packt
ISBN-13 9781789345803
Length 212 pages
Edition 1st Edition
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Author (1):
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Nazia Habib Nazia Habib
Author Profile Icon Nazia Habib
Nazia Habib
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Table of Contents (14) Chapters Close

Preface 1. Section 1: Q-Learning: A Roadmap
2. Brushing Up on Reinforcement Learning Concepts FREE CHAPTER 3. Getting Started with the Q-Learning Algorithm 4. Setting Up Your First Environment with OpenAI Gym 5. Teaching a Smartcab to Drive Using Q-Learning 6. Section 2: Building and Optimizing Q-Learning Agents
7. Building Q-Networks with TensorFlow 8. Digging Deeper into Deep Q-Networks with Keras and TensorFlow 9. Section 3: Advanced Q-Learning Challenges with Keras, TensorFlow, and OpenAI Gym
10. Decoupling Exploration and Exploitation in Multi-Armed Bandits 11. Further Q-Learning Research and Future Projects 12. Assessments 13. Other Books You May Enjoy

The learning parameters – alpha, gamma, and epsilon

Here's an updated version of the Bellman equation:

Compare it to the version we used in the last section:

In the new version, we've added in an alpha term, which means we need to include the current Q-value of the state-action pair and discount it by the alpha value.

The first equation is telling us that the new Q-value (the right side of the equation) of our state-action pair is equal to the old Q-value plus the current reward and the discounted future reward, minus the old Q-value multiplied by the alpha term. Because the alpha value is relatively small, more of the current Q-value is incorporated into the new Q-value. In both versions of the equation, because the gamma value is also relatively small, current rewards are valued more highly than future rewards.

Notice that, if the alpha value is 1, the first...

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