This open access book answers some of the hard questions in the field of machine learning and data mining. What if one of the most challenging problems in machine learning—clustering in high‑dimensional, complex data—could be solved not with deep learning but through simple space partitioning in linear time. It introduces a groundbreaking family of isolation‑based algorithms, from the widely adopted Isolation Forest to the more recent Isolation Kernel (IK) and Isolation Distributional Kernel (IDK), along with many new methods derived from them. Together, these approaches enable effective anomaly detection, clustering, classification, and similarity search across vector databases and complex data types such as time series, trajectories, and graphs.

Designed for machine learning and data mining researchers, data scientists, and professionals working with large or structured datasets, the book demonstrates how isolation partitions—created by isolating each point to extract distributional information from small samples—can outperform sophisticated learning‑based techniques, including deep learning, in both speed and accuracy. It presents a compelling case that clustering, traditionally considered NP‑hard, can be solved optimally in linear time through isolation‑inspired thinking, without the limitations of k‑means, Spectral Clustering, or Deep Clustering.

Beyond algorithmic innovation, the book emphasizes intuitive insights and lessons learned over eighteen years of research. It shows why understanding a problem deeply is often the key to simpler, better solutions, challenging the assumption that "deep learning is the answer." With minimal prerequisites, it invites a broad range of readers to explore how isolation‑inspired methods can redefine problem formulation and solution efficiency in machine learning.

Kai Ming Ting is a Full Professor at the National Key Laboratory for Novel Software Technology & School of Artificial Intelligence, Nanjing University. He is most renowned as the primary architect and principal driver of isolation-based methods. His seminal contributions (in collaboration with many colleagues) include the inventions of Isolation Forest, Isolation Kernel (IK) and Isolation Distributional Kernel (IDK). Isolation Forest is a widely adopted anomaly detection algorithm, which has more than 10,000 citations at scholar.google.com, and over 100,000 patents have utilized or cited Isolation Forest as recorded by patents.google.com. These isolation-based methods have transformed data mining and machine learning by enabling fast, effective solutions to tasks such as anomaly detection, clustering, and retrieval in vector databases as well as complex data types including time series, trajectories, graphs, and spatial transcriptomics and Automatic Modulation Classification. Notably, isolation-based methods often outperform deep learning models while running efficiently on CPUs. Furthermore, his research has empowered discoveries across scientific disciplines and diverse applications, reported in Nature and Science families of journals by other researchers.