Honest minority assumption
The assumption that only a minority of blockchain participants are honest and follow the rules of the protocol. If a certain majority of participants are dishonest, attacks can be made that are within the rules of the protocol but cause negative effects.
Honest minority assumptions can come in multiple forms, such as a 1-of-N assumption where only a single honest participant is required to be honest for the blockchain to hold a guarantee. For example, optimistic rollup users and nodes require a 1-of-N assumption for safety as at least one honest full node is required to monitor the rollup and submit fraud proofs in the event of fraud.