On formulating simultaneity for studying parallelism and synchronization

When studying parallel computation and synchronization one is faced with the problem of modeling the simultaneous execution of processes. Although there has been a multitude of formal means for representing such problems [2, 6, 9, 10, 13, 14, 15], invariably, when all the other complexities of the models have been stripped away, the parallelism or synchronization is studied via sequences of events. In all of these studies simultaneity of events is not studied directly. Rather, it is represented by the interleaving of the separate events into sequences, and by studying properties of the set of all such sequences.