Absolute versus relative time in process algebras

Timed process algebras are useful tools for the specification and verificat ion of real-time systems. We study the relationships between two of these a lgebras, CIPA ( closed interval process Algebra) and TCCS ( temporal CCS), which deal with temporal aspects of concurrent systems by following very di fferent interpretations: durational actions versus durationless actions, ab solute time versus relative time, timed functional behavior versus time and functional behavior, local clocks versus global clocks. We show that these different choices are not irreconcilable by presenting simple mappings fro m CIPA to TCCS which preserve the behavioral equivalences over the Two time d calculi. These results hold whenever basic actions are interpreted as eit her eager or lazy, whenever the starting time of action execution is observ ed rather than their completion time, a study on the size of the labelled t ransition systems describing the transitional semantics of CIPA processes a nd those describing the transitional semantics of their translated versions is also presented. (C) 2000 Academic Press.