On The Comparative Semantics In Process Calculi

With the rapid development of computer technology and network communication,concurrent and distributed systems that feature concurrency, distribution, real time,heterogeneity and interoperability have become the main direction of current computertechnology. The phenomenon of concurrency challenges computer scientists by itsintrinsic complexity. Di?ered from that of sequentiality, its study is just beginning.Since Milner put forth CCS, many concurrent computation models have been studied.Among these models, process algebra, such as CCS, are widely studied because of itsconcise concepts and rich available mathematical tools.Theπ-calculus, is a calculus of communicating systems in which one can naturallyexpress process with have changing structure. Not only may the component agentsof a system be arbitrarily linked, but a communication between neighbors may carryinformation which changes the linkage. The calculus is an extension of the processalgebra CCS, following work by Engberg and Nielsen who added mobility to CCSwhile preserving its algebraic properties. Theπ-calculus gains simplicity by removingall distinction between variables and constants; communication links are identified bynames, and computation is represented purely as the communication of names acrosslinks.In theoretical computer science, a bisimulation is a binary relation between statetransition system, associating systems which behave in the same way in the sense thatone system simulates the other and vice-versa. Intuitively two systems are bisimilarif they match each other's moves. In this sense, each of the systems cannot be distin-guished from the other by an observer.In this paper, we study various bisimulation relations in theπ-calculus and the spi-calculus. The relationships, such as the strict inclusion and the coincidence, betweenthe bisimulations are presented. We also provide counter-examples to show those strictinclusions. And we also study the impact of applying the testing approach to a calculus of processes with a dynamically changing structure.