Proof of correctness of Ressel's adOPTed algorithm

ll rig One of the central issues that groupware syst must address is how to maintain a consistent s when state is replicated across several sites. Com approaches to this problem often involve mutual clusion schemes, in which at most one participant m modify some aspect of the state at any given tim Such approaches suffer from several problems: dis uted mutual exclusion via locking algorithms is aw ward to implement; also, locking introduces dela into the system if two participants want to modify t same piece of state at once. Ellis and Gibbs [6] proposed the dOPT algorith for maintaining consistency. Unlike locking-bas approaches, dOPT transforms updates as they transmitted among sites. The transformed upda when applied, create the illusion that each particip executed the same sequence of operations, with same results. Under dOPT, no locking is requir dOPT was later proved incorrect.