Infinite-state graph transformation systems under adverse conditions

We present an approach for modeling adverse conditions by graph transformation systems. To this end, we introduce joint graph transformation systems which involve a system, an interfering environment, and an automaton modeling their interaction. For joint graph transformation systems, we present notions of correctness under adverse conditions. Some instances of correctness are expressible in LTL (linear temporal logic), or in CTL (computation tree logic), respectively. In these cases, verification of joint graph transformation systems is reduced to temporal model checking. To handle infinite state spaces, we incorporate the concept of well-structuredness. We discuss ideas for the verification of joint graph transformation systems using results based on well-structuredness.

Quantitative Verification of Stochastic Regular Expressions

In this article, we introduce a probabilistic verification algorithm for stochastic regular expressions over a probabilistic extension of the Action based Computation Tree Logic (ACTL*). The main results include a novel model checking algorithm and a semantics on the probabilistic action logic for stochastic regular expressions (SREs). Specific to our model checking algorithm is that SREs are defined via local probabilistic functions. Such functions are beneficial since they enable to verify properties locally for sub-components. This ability provides a flexibility to reuse the local results for the global verification of the system; hence, the framework can be used for iterative verification. We demonstrate how to model a system with an SRE and how to verify it with the probabilistic action based logic and present a preliminary performance evaluation with respect to the execution time of the reachability algorithm.

On Sufficient and Necessary Conditions in Bounded CTL: A Forgetting Approach

Computation Tree Logic (CTL) is one of the central formalisms in formal verification. As a specification language, it is used to express a property that the system at hand is expected to satisfy. From both the verification and the system design points of view, some information content of such property might become irrelevant for the system due to various reasons, e.g., it might become obsolete by time, or perhaps infeasible due to practical difficulties. Then, the problem arises on how to subtract such piece of information without altering the relevant system behaviour or violating the existing specifications over a given signature. Moreover, in such a scenario, two crucial notions are informative: the strongest necessary condition (SNC) and the weakest sufficient condition (WSC) of a given property. To address such a scenario in a principled way, we introduce a forgetting-based approach in CTL and show that it can be used to compute SNC and WSC of a property under a given model and over a given signature. We study its theoretical properties and also show that our notion of forgetting satisfies existing essential postulates of knowledge forgetting. Furthermore, we analyse the computational complexity of some basic reasoning tasks for the fragment CTLAF in particular.

A Social Multi-Agent Cooperation System Based on Planning and Distributed Task Allocation

Planning and distributed task allocation are considered challenging problems. To address them, autonomous agents called planning agents situated in a multi-agent system should cooperate to achieve planning and complete distributed tasks. We propose a solution for distributed task allocation where agents dynamically allocate the tasks while they are building the plans. We model and verify some properties using computation tree logic (CTL) with the model checker its-ctl. Lastly, simulations are performed to verify the effectiveness of our proposed solution. The result proves that it is very efficient as it requires little message exchange and computational time. A benchmark production system is used as a running example to explain our contribution.

Computation Tree Logic Formula Model Checking Using DNA Computing

Computation tree logic model checking is a formal verification technology that can ensure the correctness of systems. The vast storage density of deoxyribonucleic acid (DNA) molecules and the massive parallelism of DNA computing offer new methods for computation tree logic model checking. In this study, we propose a computation tree logic model checking method based on DNA computing. First, a system to-be-checked and a computation tree logic formula are encoded by single-stranded DNA molecules. Second, these singlestranded DNA molecules are mixed to spontaneously hybridize and form partial or complete double-stranded molecules. Finally, a series of molecular manipulations are applied to detect the double-stranded molecules so that the result whether the system satisfies the computation tree logic formula is obtained. Biological simulations confirm the validity of the new method.