Happened Before is the Wrong Model for Potential Causality.

Ashis Tarafdar and Vijay K. Garg.

Abstract

The happened before model has been widely used to model distributed computations. In particular, it has been used to model the logical time and the potential causality aspects of a distributed computation. Though it is a good model for logical time, we argue that it is not a good model for potential causality. We introduce a better model for potential causality that extends happened before to allow independent local events to be partially ordered. This potential causality model has marked advantages over the happened before model in applications areas such as debugging and recovery.