In recent years, significant research efforts have focused on improving blockchain throughput and confirmation speeds without compromising security. While decreasing the time it takes for a transaction to be included in the blockchain ledger enhances user experience, a fundamental delay still remains between when a transaction is issued by a user and when its inclusion is confirmed in the blockchain ledger. This delay limits user experience gains through the confirmation uncertainty it brings for users. This inherent delay in conventional blockchain protocols has led to the emergence of preconfirmation protocols -- protocols that provide users with early guarantees of eventual transaction confirmation. This article presents a Systematization of Knowledge (SoK) on preconfirmations. We present the core terms and definitions needed to understand preconfirmations, outline a general framework for preconfirmation protocols, and explore the economics and risks of preconfirmations. Finally, we survey and apply our framework to several implementations of real-world preconfirmation protocols, bridging the gap between theory and practice.

翻译：近年来，大量研究工作聚焦于在不牺牲安全性的前提下提升区块链的吞吐量与确认速度。虽然缩短交易被纳入区块链账本的时间能够改善用户体验，但用户发起交易到其在账本中被确认之间仍存在根本性延迟。这种延迟带来的确认不确定性限制了用户体验的提升。传统区块链协议中固有的这一延迟催生了预确认协议——即向用户提供最终交易确认早期保证的协议。本文提出了关于预确认的系统化知识（SoK）。我们阐述了理解预确认所需的核心术语与定义，勾勒了预确认协议的一般框架，并探讨了预确认的经济性与风险。最后，我们对多个实际预确认协议的实现进行了调研，并将我们的框架应用于这些案例，以此弥合理论与实践之间的鸿沟。