Communicating and Mobile Systems: the Pi-Calculus

Rating:
Summary: Optimal as a starter in pi-calculus
Review: How can we describe communicating mobile systems? How can we state that a communicating system "behaves as", and therefore "can be replaced with", another one? This short book (about 150 pages plus bibliography, TOC and index) gives an answer to these questions. The books is in two parts: The first presents CCS, the simpler formalism from which pi-calculus originated, which does not model information exchange between communicating systems. From hence the more complex pi-calculus is presented. The aim is presenting the theory of equivalences between communicating processes, based on bisimulation. First a language for processes is introduced, with its formal syntax and its semantics, then a theory of behavioral equivalence is developed via the bisimilarity concept, and observation equivalence between processes is introduced as a particular flavour of bisimilarity. Finally is proved how a process can be freely replaced by an equivalent one in any context without affecting the overall behavior.
If you are a student or researcher in the field of formal methods for describing and reasoning on communicating systems the book is definitely a must: It introduces quickly many key concepts of pi-calculus, bisimulation and observational semantics. It is also well written, ideal for students. Its plus is the strong link between CCS and pi-calculus, and the fact that, coming after a long experience with the zillions of variants of the pi-calculus, this presents a very clean and self-contained variant. This is also its downside: Some concepts are not introduced, like early and late variants of strong bisimulations. Also, two semantics are presented, labelled transition systems and reduction systems, but without explaining why, nor a bisimulation is given for the reduction system. As a result, it seems that reduction semantics is there just as an exercise, but that we do not really need it. It would have been nicer if the topics were presented with a historical perspective.
More aware readers would prefer other books, like Sangiorgi and Walker. Remember that the book's purpose is presenting a theory of equivalence between communicating systems, not presenting complex applications of this theory (the examples just serve the purpose to enlighten the concepts).

Rating:
Summary: good overview of pi, but a bit thick on formalism at times
Review: This is a very good overview of pi-calculus, It starts off well with a review of automata theory and then extends it to communication and concurrency. It focuses more on the principles than on practical aspects of using it for real systems. It uses good examples throughout, and with the formalistic presentation it requires careful attention of the reader. It is hard read at times but worth it. However, this is not for a casual reader but for the really motivated.