Consensus ·A set of n nodes{1,2,…,n} Input of node i:some value vi Output of node i:some value outi Requirement:all nodes have identical output value. Termination:each node eventually outputs some value. Agreement:all nodes output identical value Validity:final output value is some node's initial value Applications in distributed computing: 北京 Electing a leader among nodes Replicating data into nodes Taking a commit decision 成都 上海Consensus • A set of 𝑛 nodes 1,2, ⋯ , 𝑛 Input of node 𝑖: some value 𝑣𝑖 Output of node 𝑖: some value 𝑜𝑢𝑡𝑖 Requirement: all nodes have identical output value. • Termination: each node eventually outputs some value. Agreement: all nodes output identical value. Validity: final output value is some node’s initial value. 北京 成都 上海 Applications in distributed computing: • Electing a leader among nodes • Replicating data into nodes • Taking a commit decision • …