TCTL Inevitability Analysis of Dense-Time Systems

Abstract

Inevitability properties in branching temporal logics are of the syntax ∀♦φ, where φ is an arbitrary (timed) CTL formula. In the sense that "good things will happen", they are parallel to the "liveness" properties in linear temporal logics. Such inevitability properties in dense-time logics can be analyzed with greatest fixpoint calculation. We present algorithms to model-check inevitability properties both with and without requirement of non-Zeno computations. We discuss a technique for early decision on greatest fixpoints in the temporal logics. Our algorithms come with a d-parameter for the measurement of time-progress. We have experimented with various issues, which may affect the performance of TCTL inevitability analysis. Specifically, we report the performance of our implementation w.r.t. various d-parameter values and with or without the non-Zeno computation requirement in the evaluation of greatest fixpoints. We have also experimented with safe abstration techniques for model-checking TCTL inevitability properties. Analysis on the experiment data helps clarify how various techniques can be used to improve verification of inevitability properties.

Efficient verification of distributed real-time systems with broadcasting behaviors

“…We have implemented the ideas in our model-checker/simulator (Wang 2005;Wang et al 2006), RED version 8.0, for timed automata. It has been implemented with BDD-like diagram, CRD (Clock-Restriction Diagram) (Wang 2004b).…”

Testing Deadlock-Freeness in Real-Time Systems: A Formal Approach

“…Various interpretations of deadlock are extensively studied in the literature [8,7,27,16,28]. There are two different forms of Timelock [8], Zeno Timelock and Time Action Lock.…”

“…Various types of deadlock in Real-time systems are studied in the literature [16,8,7,27,28]. In particular, a Time Lock [27] is a state at which time is prevented from passing beyond a certain point, and Time Action Lock [8] is a Time Lock state at which no action can occur.…”

Symbolic parametric safety analysis of linear hybrid systems with BDD-like data-structures

“…In [11], CDD only served as a recording device in that reachable state-space representations were analyzed using DBM [13] and then converted for recording to CDD. In [25], [27], [26], a full set of verification algorithms (including forward/backward reachability analysis, normalization, and full TCTL model-checking procedures) for CRD were reported.…”

“…RED 5.3 supports full TCTL model-checking/simulation with graphical user-interface. Techniques for coverage estimation of dense-time state-spaces and fast greatest fixpoint evaluation have been reported [27], [28]. In addition, we have also compared with HyTech 2.4.5 [15] and TReX 1.3 [1], [3] against several benchmarks.…”