par Chockler, Hana;Guha, Shibashis 
;Kupferman, Orna
Référence Lecture notes in computer science, 10951 LNCS, page (438-455)
Publication Publié, 2018
;Kupferman, OrnaRéférence Lecture notes in computer science, 10951 LNCS, page (438-455)
Publication Publié, 2018
Article révisé par les pairs
| Résumé : | Vacuity is a leading sanity check in model-checking, applied when the system is found to satisfy the specification. The check detects situations where the specification passes in a trivial way, say when a specification that requires every request to be followed by a grant is satisfied in a system with no requests. Such situations typically reveal problems in the modelling of the system or the specification, and indeed vacuity detection is a part of most industrial model-checking tools. Existing research and tools for vacuity concern discrete-time systems and specification formalisms. We introduce real-time vacuity, which aims to detect problems with real-time modelling. Real-time logics are used for the specification and verification of systems with a continuous-time behavior. We study vacuity for the branching real-time logic TCTL, and focus on vacuity with respect to the time constraints in the specification. Specifically, the logic TCTL includes the temporal operator UJ, which specifies real-time eventualities in real-time systems: the parameter is an interval with integral boundaries that bounds the time in which the eventuality should hold. We define several tightenings for the UJ operator. These tightenings require the eventuality to hold within a strict subset of J. We prove that vacuity detection for TCTL is PSPACE-complete, thus it does not increase the complexity of model-checking of TCTL. Our contribution involves an extension, termed TCTL +, of TCTL, which allows the interval J not to be continuous, and for which model checking stays in PSPACE. Finally, we describe a method for ranking vacuity results according to their significance. |
