This book constitutes the thoroughly refereed post conference papers of the Third International Conference on Blockchain and Trustworthy Systems, Blocksys 2021, held in Guangzhou, China, in August 2021.*The 38 full papers and the 12 short papers were carefully reviewed and selected from 98 submissions. The papers are organized in topical sections: Contents Blockchain and Data Mining; Performance Optimization of Blockchain; Blockchain Security and Privacy; Theories and Algorithms for Blockchain; Blockchain and Internet of Things; Blockchain and Smart Contracts; Blockchain Services and Applications; Trustworthy System Development.*

The Metaverse seamlessly integrates the real world with the virtual world and allows avatars to engage in a broad range of activities including entertainment, social networking, and trading. In this book, we dive into the Metaverse by discussing how blockchains connect various Metaverse components, digital currencies, and blockchain-empowered applications in the virtual world. On the other hand, Web3 has also attracted considerable attention due to its uniquely decentralized characteristics. The digital economy, currently undergoing a rapid development, is a critical driver to highly efficient societies. It is imperative that we investigate how to use Web3 technologies to address the critical concerns encountered during the development of the digital economy by fully exploring Web3. In this book, we also share insights into the Web3-based ecosystem in the Metaverse; topics of interest include decentralized finance, digital assets, the asset-trading market, etc. Unlike most works on the subject, this book mainly concentrates on insights and discussions regarding blockchain, the Metaverse and Web3. In other words, it focuses on using blockchain technologies to enable an ecosystem for both the Metaverse and Web3. Topics addressed include blockchain fundamentals, smart contracts, value circulation in the Metaverse, the connection between the Metaverse and Web3, the establishment of the Metaverse on the basis of blockchain technologies, decentralized autonomous organization, decentralized storage, digital economy, Web3-based economic systems for the Metaverse, etc. This book will be a valuable resource for students, researchers, engineers, and policymakers working in various areas related to blockchain, the Metaverse and Web3. We hope that it will also inspire readers from academia and industry alike, and ultimately help them create a truly open, fair, and rational ecosystem for the Metaverse and Web3.

Unifying Themes in Complex Systems is a well-established series of carefully edited conference proceedings that serve to document and archive the progress made regarding cross-fertilization in this field. The International Conference on Complex Systems (ICCS) creates a unique atmosphere for scientists from all fields, engineers, physicians, executives, and a host of other professionals, allowing them to explore common themes and applications of complex systems science. With this new volume, Unifying Themes in Complex Systems continues to establish common ground between the wide-ranging domains of complex systems science.

This book focuses on using artificial intelligence (AI) to improve blockchain ecosystems. Gathering the latest advances resulting from AI in blockchain data analytics, it also presents big data research on blockchain systems. Despite blockchain's merits of decentralisation, immutability, non-repudiation and traceability, the development of blockchain technology has faced a number of challenges, such as the difficulty of data analytics on encrypted blockchain data, poor scalability, software vulnerabilities, and the scarcity of appropriate incentive mechanisms. Combining AI with blockchain has the potential to overcome the limitations, and machine learning-based approaches may help to analyse blockchain data and to identify misbehaviours in blockchain. In addition, deep reinforcement learning methods can be used to improve the reliability of blockchain systems. This book focuses in the use of AI to improve blockchain systems and promote blockchain intelligence. It describes data extraction, exploration and analytics on representative blockchain systems such as Bitcoin and Ethereum. It also includes data analytics on smart contracts, misbehaviour detection on blockchain data, and market analysis of blockchain-based cryptocurrencies. As such, this book provides researchers and practitioners alike with valuable insights into big data analysis of blockchain data, AI-enabled blockchain systems, and applications driven by blockchain intelligence.