Logical time in distributed software systems

This paper presents a survey of implementation of logical time in asynchronous distributed systems. We provide an argument that justifies the use of logical time as a mechanism for detecting causal relationships between events. Further, we formally introduce the notion of a logical time system (a logical clock) and proceed to discuss the properties of the scalar, vector, and matrix clocks. Finally, we consider the modifications of the vector clock that reduce the average communication overhead while retaining the property of isomorphism.