打磨7年，李航新书《机器学习方法（第2版）》发布，有了强化学习，赠书20本

Core Viewpoint - The article discusses the release of the second edition of "Machine Learning Methods" by Li Hang, which expands on traditional machine learning to include deep learning and reinforcement learning, addressing the growing interest in these areas within the AI community [4][5][22]. Summary by Sections Overview of the Book - The new edition of "Machine Learning Methods" includes significant updates and additions, particularly in reinforcement learning, which has been gaining attention in AI applications [4][5]. - The book is structured into four main parts: supervised learning, unsupervised learning, deep learning, and reinforcement learning, providing a comprehensive framework for readers [5][22]. Supervised Learning - The first part covers key supervised learning methods such as linear regression, perceptron, support vector machines, maximum entropy models, logistic regression, boosting methods, hidden Markov models, and conditional random fields [7]. Unsupervised Learning - The second part focuses on unsupervised learning techniques, including clustering, singular value decomposition, principal component analysis, Markov chain Monte Carlo methods, EM algorithm, latent semantic analysis, and latent Dirichlet allocation [8]. Deep Learning - The third part introduces major deep learning methods, such as feedforward neural networks, convolutional neural networks, recurrent neural networks, Transformers, diffusion models, and generative adversarial networks [9]. Reinforcement Learning - The fourth part details reinforcement learning methods, including Markov decision processes, multi-armed bandit problems, proximal policy optimization, and deep Q networks [10]. - The book aims to provide a systematic introduction to reinforcement learning, which has been less covered in previous textbooks [4][10]. Learning Approach - Each chapter presents one or two machine learning methods, explaining models, strategies, and algorithms in a clear manner, supported by mathematical derivations to enhance understanding [12][19]. - The book is designed for university students and professionals, assuming a background in calculus, linear algebra, probability statistics, and computer science [22]. Author Background - Li Hang, the author, is a recognized expert in the field, with a background in natural language processing, information retrieval, machine learning, and data mining [24].