Blockchain introduces decentralized trust in peer-to-peer networks, advancing security and democratizing systems. Yet, a unified definition for decentralization remains elusive. Our Systematization of Knowledge (SoK) seeks to bridge this gap, emphasizing quantification and methodological coherence. We've formulated a taxonomy defining blockchain decentralization across five facets: consensus, network, governance, wealth, and transaction. Despite the prevalent focus on consensus decentralization, our novel index, based on Shannon entropy, provides comprehensive insights. Moreover, we delve into alternative metrics like the Gini and Nakamoto Coefficients and the Herfindahl-Hirschman Index (HHI), supplemented by an open-source Python tool on GitHub.In terms of methodology, blockchain research has often bypassed stringent scientific methods. By employing descriptive, predictive, and causal methods, our study showcases the potential of structured research in blockchain. Descriptively, we observe a trend of converging decentralization levels over time. Examining DeFi platforms reveals exchange and lending applications as more decentralized than their payment and derivatives counterparts. Predictively, there's a notable correlation between Ether's returns and transaction decentralization in Ether-backed stablecoins. Causally, Ethereum's transition to the EIP-1559 transaction fee model has a profound impact on DeFi transaction decentralization. To conclude, our work outlines directions for blockchain research, emphasizing the delicate balance among decentralization facets, fostering long-term decentralization, and the ties between decentralization, security, privacy, and efficiency. We end by spotlighting challenges in grasping blockchain decentralization intricacies.

翻译：论文摘要：区块链在点对点网络中引入了去中心化信任机制，推动了系统安全性与民主化进程。然而，去中心化至今仍缺乏统一的定义。本知识系统化研究（SoK）旨在弥合这一差距，重点聚焦量化方法与方法论一致性。我们构建了涵盖共识、网络、治理、财富与交易五个维度的区块链去中心化分类体系。尽管当前研究多聚焦于共识去中心化，但基于香农熵构建的新型指数提供了更全面的洞察。此外，我们深入探讨了基尼系数、中本聪系数及赫芬达尔-赫希曼指数（HHI）等替代性指标，并配套发布了GitHub开源Python工具。在方法论层面，区块链研究常缺乏严谨的科学方法。通过采用描述性、预测性与因果性方法，本研究展示了结构化研究的潜力：描述性分析揭示了去中心化水平随时间趋于收敛的趋势；对DeFi平台的考察表明，交易所与借贷类应用比支付与衍生品应用更具去中心化特征；预测性分析显示，以太坊支持的稳定币中，其回报率与交易去中心化程度存在显著相关性；因果性分析则表明，以太坊向EIP-1559交易费用模型的转型对DeFi交易去中心化产生了深远影响。最后，我们为区块链研究指明了方向，强调去中心化各维度间的微妙平衡、长期去中心化的培育，以及去中心化与安全性、隐私性、效率性之间的内在关联，并剖析了理解区块链去中心化复杂性的挑战。