Rollback based on vector time

Causality, as made concrete by Lamport\´s "happened before" relation, is the central underlying basis in the design of optimistic protocols for checkpoint and recovery. After the recovery of a formerly failed process, all events and messages which causally follow the events and messages discarded by restoration of a state checkpoint must be discarded also. The isomorphism between causality and vector time is well-known. That isomorphism is exploited here in order to develop and verify a simple and effective protocol which explicitly uses the causal partial order, through the use of vector time, in order to rollback a computation in response to a process failure