Background: Logical Time
Happens before (?)
- a?b if
- a and b occur at the same process, and a occurs before b
- a is the event of sending a message, and b is the event of receiving the same message
- there is some event c such that a ?c and c ?b
- a?b ? t(a) < t(b)
- L. Lamport, “Time, Clocks, and the Ordering of Events in a Distributed System,” Comm. of the ACM 21,7 (July 1978)