DEEP REINFORCEMENT LEARNING:AN OVERVIEW Yuxi Li (
[email protected]) ABSTRACT We give an overview of recent exciting achievements of deep reinforcement learn- ing (RL). We discuss six core elements, six important mechanisms, and twelve applications. We start with background of machine learning, deep learning and reinforcement learning. Next we discuss core RL elements, including value func- tion, in particular, Deep Q-Network (DQN), policy, reward, model, planning, and exploration. After that, we discuss important mechanisms for RL, including atten- tion and memory, in particular, differentiable neural computer (DNC), unsuper- vised learning, transfer learning, semi-supervised learning, hierarchical RL, and learning to learn. Then we discuss various applications of RL, including games, in particular, AlphaGo, robotics, natural language processing, including dialogue systems (a.k.a. chatbots), machine translation, and text generation, computer vi- sion, neural architecture design, business management, finance, healthcare, Indus- try 4.0, smart grid, intelligent transportation systems, and computer systems. We mention topics not reviewed yet. After listing a collection of RL resources, we present a brief summary, and close with discussions. arXiv:1701.07274v3 [cs.LG] 15 Jul 2017 1 CONTENTS 1 Introduction5 2 Background6 2.1 Machine Learning . .7 2.2 Deep Learning . .8 2.3 Reinforcement Learning . .9 2.3.1 Problem Setup . .9 2.3.2 Value Function . .9 2.3.3 Temporal Difference Learning . .9 2.3.4 Multi-step Bootstrapping . 10 2.3.5 Function Approximation . 11 2.3.6 Policy Optimization . 12 2.3.7 Deep Reinforcement Learning . 12 2.3.8 RL Parlance . 13 2.3.9 Brief Summary .