Quorum Intersection

Quorum intersection is a design requirement for consensus protocols ensuring that any two sets of nodes authorized to make a decision overlap. This overlap guarantees that there is at least one honest node that can prevent conflicting decisions from being finalized.

If a system allows two different quorums to reach different conclusions simultaneously, the ledger would split, causing a fork. By strictly enforcing quorum intersection, protocols maintain the integrity and consistency of the chain.

This is a mathematical guarantee that is foundational to the security of Byzantine Fault Tolerant systems. It dictates the minimum number of nodes required to reach a decision relative to the total network size.

Understanding this concept is vital for analyzing the safety properties of a blockchain. It ensures that the network acts as a single, unified entity.

If quorum intersection is compromised, the entire security model of the decentralized system collapses. It is a core principle in the design of secure, distributed consensus mechanisms.