© 2001 by Oxford University Press
Original Article |
Which Branching-Time Properties are Effectively Linear?
1 Computer Science Department, The Technion, Haifa 32000, Israel. E-mail: orna{at}cs.technion.ac.il 2 Bell Laboratories, Murray Hill, NJ 07974, USA. E-mail: k{at}research.bell-labs.com
We characterize three successively more restrictive classes of effectively linear CTL* formulas, with and without fairness: the equi-linear formulas, which do not distinguish among models with the same language, the sub-linear formulas, which are preserved under model language inclusion and the strong linear formulas, which are characterized by a given
-regular language. Moreover, strong linearity characterizes those CTL* formulas equivalent to LTL formulas. This taxonomy helps to clarify the expressive distinctions between CTL*, LTL and
-regular languages. It has also practical implications. Verification tools based on language inclusion can handle any CTL* formula which is equi-linear, for purposes of model checking, and sub-linear for purposes of abstraction. Furthermore, minimization techniques that preserve the subset of CTL* which consists of only effectively linear formulas, result in smaller structures than bisimulation minimization.
Keywords: Temporal logic; linear temporal logic; branching temporal logic; fairness; characterization
Received 29 March 1999.