Reducing Validity in Epistemic ATL to Validity in Epistemic CTL

We propose a validity preserving translation from a subset of epistemic Alternating-time Temporal Logic (ATL) to epistemic Computation Tree Logic (CTL). The considered subset of epistemic ATL is known to have the finite model property and decidable model-checking. This entails the decidability of validity but the implied algorithm is unfeasible. Reducing the validity problem to that in a corresponding system of CTL makes the techniques for automated deduction for that logic available for the handling of the apparently more complex system of ATL.Comment: In Proceedings SR 2013, arXiv:1303.007

Specification and verification of reconfiguration protocols in grid component systems

In this work we present an approach for the formal specification and verification of the reconfiguration protocols in Grid component systems. We consider Fractal, a modular and extensible component model. As a specification tool we invoke a specific temporal language, separated clausal normal form, which has been shown to be capable of expressing any ECTL+ expression thus, we are able to express the complex fairness properties of a component system. The structure of the normal enables us to directly apply the deductive verification technique, temporal resolution defined in the framework of branching-time temporal logic

Dynamic reconfiguration of GCM components

We detail in this report past research and current/future developments in formal specification of Grid component systems by temporal logic and consequent resolution technique, for an automated dynamic reconfiguration of components. It is analysed the specification procedure of GCM (Grid Component Model) components and infrastructure in respect to their state behaviour, and the verification process in a dynamic and reconfigurable distributed system. Furthermore it is demonstrated how an automata based method is used to achieve the specification, as well as how the enrichment of the temporal specification language of Computation Tree Logic CTL with the ability to capture norms, allows to formally define the concept of reconfiguration

On the Expressive Power of the Normal Form for Branching-Time Temporal logics

With the emerging applications that involve complex distributed systems branching-time specifications are specifically important as they reflect dynamic and non-deterministic nature of such applications. We describe the expressive power of a simple yet powerful branching-time specification framework – branching-time normal form, which has been developed as part of clausal resolution for branching-time temporal logics. We show the encoding of B¨uchi Tree Automata in the language of the normal form, thus representing, syntactically, tree automata in a high-level way. Thus we can treat BNF as a normal form for the latter. These results enable us (1) to translate given problem specifications into the normal form and apply as a verification method a deductive reasoning technique – the clausal temporal resolution; (2) to apply one of the core components of the resolution method - the loop searching to extract, syntactically, hidden invariants in a wide range of complex temporal specifications

Satisfiability Games for Branching-Time Logics

The satisfiability problem for branching-time temporal logics like CTL*, CTL and CTL+ has important applications in program specification and verification. Their computational complexities are known: CTL* and CTL+ are complete for doubly exponential time, CTL is complete for single exponential time. Some decision procedures for these logics are known; they use tree automata, tableaux or axiom systems. In this paper we present a uniform game-theoretic framework for the satisfiability problem of these branching-time temporal logics. We define satisfiability games for the full branching-time temporal logic CTL* using a high-level definition of winning condition that captures the essence of well-foundedness of least fixpoint unfoldings. These winning conditions form formal languages of \omega-words. We analyse which kinds of deterministic {\omega}-automata are needed in which case in order to recognise these languages. We then obtain a reduction to the problem of solving parity or B\"uchi games. The worst-case complexity of the obtained algorithms matches the known lower bounds for these logics. This approach provides a uniform, yet complexity-theoretically optimal treatment of satisfiability for branching-time temporal logics. It separates the use of temporal logic machinery from the use of automata thus preserving a syntactical relationship between the input formula and the object that represents satisfiability, i.e. a winning strategy in a parity or B\"uchi game. The games presented here work on a Fischer-Ladner closure of the input formula only. Last but not least, the games presented here come with an attempt at providing tool support for the satisfiability problem of complex branching-time logics like CTL* and CTL+