Focus points and convergent process operators: A proof strategy for protocol verification
Jan Friso Groote, Jan Springintveld
; Department of Philosophy, Utrecht University; CWI
; Heidelberglaan 8, 3584 CS Utrecht, The Netherlands; P.O. Box 94079, 1090 GB Amsterdam, The Netherlands
We present a strategy for finding algebraic correctness proofs for communication systems. It is described in the setting of µCRL , which is, roughly, ACP [2, 3] extended with a formal treatment of the interaction between data and processes. The strategy has already been applied successfully in  and , but was not explicitly identified as such. Moreover, the protocols that were verified in these papers were rather complex, so that the general picture was obscured by the amount of details. In this paper, the proof strategy is materialised in the form of definitions and theorems. These results reduce a large part of protocol verification to a number of trivial facts concerning data parameters occurring in implementation and specification. This greatly simplifies protocol verifications and makes our approach amenable to mechanical assistance � experiments in this direction seem promising. The strategy is illustrated by several small examples and one larger example, the Concurrent Alternating Bit Protocol (CABP). Although simple, this protocol contains a large amount of internal parallelism, so that all relevant issues make their appearance.