1,721,023 research outputs found
A Model Checking Approach for Verifying COWS Specifications
Full text linkWe introduce a logical verification framework for checking functional properties of service-oriented applications formally specified using the service specification language COWS. The properties are described by means of SocL, a logic specifically designed to capture peculiar aspects of services. Service behaviours are abstracted in terms of Doubly Labelled Transition Systems, which are used as the interpretation domain for SocL formulae. We also illustrate the SocL model checker at work on a bank service scenario specified in COWS
Application of Correctness preserving Transformations for Deriving Architectural Descriptions of Interactive Systems from User Interface Specifications
No full textFormally verifying fault tolerant system designs
No full textThis paper presents an approach for the specification and the verification of the correctness of fault tolerant system designs achieved by the application of fault tolerant techniques. The approach is based on process algebras, equivalence theory and temporal logic. The behaviour of the system in the absence of faults is formally specified and faults are assumed as random events which interfere with the system by modifying its behaviour. The fault tolerant technique is formalized by a context that specifies how replicas of the system cooperate to deal with faults. The system design is proved to behave correctly under a given fault hypothesis by proving the observational equivalence between the system design specification and the fault-free system specification. Additionally, model checking of a temporal logic formula which gives an abstract notion of correct behaviour can be applied to verify the correctness of the design. The opportunities given by the expression of the fault hypothesis using temporal logic are discussed. The actual usability of the approach in real case studies is supported by the availability of automatic tools for equivalence checking and for proving the temporal logic properties by model checking
Validating the Design of Dependable Systems
No full textThis paper reports an approach for the specification and verification of the correctness of dependable system designs achieved by the application of fault tolerant techniques based on equivalence relations and model checking techniques. The behaviour of the system in absence of faults is formally specified and faults are assumed as random events which interfere with the system by modifying its behaviour: The fault tolerant technique is formalized by a context, which specifies how replicas of the system cooperate to deal with faults. The system design is proved to satisfy the correctness property under a given fault hypothesis, by proving the observational equivalence between the system design specification and the fault-free system specification. Additionally, model checking of a temporal logic formula which gives an abstract notion of correct behaviour can be applied to verify the correctness of the design
A Framework to Evaluate 5G Networks for Smart and Fail-Safe Communications in ERTMS/ETCS
No full textETCS is an European system for high speed trains control and protection within ERTMS, the European standard for rail traffic management system. ERTMS/ETCS implementations use GSM-R for communications. As GSM-R is becoming obsolete, the adoption of more advanced technologies is investigated for next generation trains. New communication systems for railway infrastructures are expected to overcome the limitations of GSM-R, providing enhanced performance and reliability, as well as safety and security functionality to meet the requirements of the future signalling systems, control and users’ applications. While 4G technologies (LTE and LTE-A) are currently tested in a few field trials, railway operators should consider that fifth generation (5G) mobile communications technologies will soon be available. One of the foundational aspects of the 5G architecture is control-plane programmability, achieved through the SDN paradigm. Being aware that in a railway scenario this opportunity can be exploited to dynamically reconfigure the network behavior to better match the communication flows produced by moving trains, we aim at defining a framework, integrating formal modeling and analysis tools and techniques into a network emulator, to evaluate the impact on ERTMS/ETCS safety and security deriving from the adoption of an SDN model in the communication infrastructure. In this paper we describe a first step towards this objective, by presenting a first proof-of-concept implementation of the framework and its use to reproduce a simple railway infrastructure. In our current implementation, Finite State Machines are used to model communication protocols between ERTMS/ETCS entities and to automatically produce code and Promela models. Generated code is directly used to control the network behavior while the Promela model allows to generate and verify a network configuration by model checking
Formal Verification of Safety Requirements on Complex Systems
No full textIn this paper we present a logical characterization, by means of ACTL formulae, of safety requirements to be formally verified over safety critical complex systems. In this class of systems the formal verification of requirements is often hardened by state explosion problems. To deal with this problem, the characterization we propose allows the satisfiability of a safety requirement over a complex system to be derived by its satisfiability over those component subsystems that are directly involved in the given requirement. The proposed methodology has been successfully used for the formal verification of safety requirements of a particular system, that is a railway computer based signalling control system
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