Practical Byzantine Fault Tolerance

The document discusses Byzantine Fault Tolerance (BFT) in decentralized systems, outlining the characteristics of Byzantine faults, the replicated state machine problem, and the challenges in maintaining consistent state among processes. It presents a high-level algorithm for request processing, describes a view change mechanism to handle faulty nodes, and introduces the query/update (Q/U) protocol that aims to facilitate fault-scalability and improve the efficiency of operations in the context of Byzantine faults. The document also delves into various strategies for concurrency control, repair mechanisms, and optimizations to enhance system performance while tolerating faults.