Process interaction models are an integral component of parallel computing theory and practice, defining the means by which concurrent processes interact; where "interaction" means not only the exchange of data but also synchronization between processes. In the search for a general purpose model to program parallel computers and reason about the partial orders of data in such systems, it is desirable to provide portability, an expressiveness that does not distract the programmer from the task in hand and efficiency independent of the memory architecture of the machine. This book discusses...