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Model-checking strategy-controlled rewriting systems

Strategies are a widespread but ambiguous concept in Computer Science. In the domain of reduction and rewriting systems, strategies are studied as recipes to restrict and control reduction steps and rule applications, which are intimately local, in a derivation-global sense. This idea has been exploited by various tools and rewriting-based specification languages where strategies are an additional specification layer. Systems so described need to be analyzed too. This article discusses model checking of systems controlled by strategies and presents a working strategy-aware model checker built on top of the Maude specification language, based on rewriting logic, and its strategy language.Pendiente de publicación en «International Conference on Formal Structures for Computation and Deduction» (FSCD) 2019. Se envía la versión aceptada. La versión definitiva estará lista a finales de abril.

Extending Fairness Expressibility of ECTL+: A Tree-Style One-Pass Tableau Approach

25th International Symposium on Temporal Representation and Reasoning (TIME 2018)Warsaw, Poland 15-17 October 2018.

An extension of TRIANGLE testbed with model-based testing (Trabajo ya publicado)

Traditional testing methods for mobile apps focus on detecting execution errors. However, the evolution of mobile networks towards 5G will require additional support for app developers to ensure also the performance and user-experience. Manual testing in a number of scenarios is not enough to satisfy the expectations of the apps final users. This paper presents the testing framework developed in the TRIANGLE project1 that integrates a complete mobile network testbed and a model-based testing approach, which is based on model checking, to automatically evaluate the apps performance in different network scenarios.

Context-based Model Checking using SMT-solvers (Trabajo en progreso)

In this paper we propose a new idea for the implementation of symbolic model checking. Our pro- posal takes advantage of two technologies. First, SMT-solvers as efficient auxiliary tools to perform a large proportion of the computational task. Second, the context-based tableau that is especially well suited for providing certificates of proved properties, as well as counterexamples of disproved properties. We mainly introduce the algorithm to be implemented, along with illustrative examples.

Constrained Dynamic Partial Order Reduction (Trabajo ya publicado)

The cornerstone of dynamic partial order reduction (DPOR) is the notion of independence that is used to decide whether each pair of concurrent events p and t are in a race and thus both p·t and t·p must be explored. We present constrained dynamic partial order reduction (CDPOR), an extension of the DPOR framework which is able to avoid redundant explorations based on the notion of conditional independence —the execution of p and t commutes only when certain independence constraints (ICs) are satisfied. ICs can be declared by the programmer, but importantly, we present a novel SMT-based approach to automatically synthesize ICs in a static pre-analysis. A unique feature of our approach is that we have succeeded to exploit ICs within the state-of-the-art DPOR algorithm, achieving exponential reductions over existing implementations.

Towards a formal framework for analyzing stream processing systems in Maude (Trabajo en progreso)

With the rise of Big Data technologies, distributed stream processing systems (SPS) have gained popularity in the last years. Among these systems Spark Streaming stands out as a particularly attractive option, with a growing adoption in the industry, so we will consider in particular some features of SPS in Spark Streaming. Maude is a high-performance logical framework where other systems can be easily specified and executed. In this paper we show how a Maude specification of Spark Streaming would allow developers to analyze and prove properties on their programs.

A characterisation of reliability tools for Software Defined Networks (Trabajo original)

Software Defined Network (SDN) is a new paradigm in networking that introduces great flexibility, allowing the dynamic configuration of parts of the network through centralised programming. SDN has been successfully applied in field networks, and is now being applied to wireless and mobile networks, generating Software Defined Mobile/Wireless networks (SDWNs). SDN can be also combined with Network Function Virtualization (NFV) producing a software network in which the specific hardware is replaced by general purpose computing equipment running SDN and NFV software solutions. This highly programmable and flexible network introduces many challenges from the point of view of reliability (or robustness), and operators need to ensure the same level of confidence as in previous, less flexible deployments. This paper provides a first study of the current tools used to analyse the reliability of SDNs before deployment and/or during the exploitation of the network. Most of these tools offer some kind of automatic verification, supported by algorithms based on formal methods, but they do not differentiate between fixed and mobile/wireless networks. In the paper we provide a number of classifications of the tools to make this selection easier for potential users, and we also identify promising research areas where more effort needs to be made.

Analyzing Hybrid Systems with JPF

Hybrid systems are characterized by combining discrete and continuous behaviors. Verification of hybrid systems is, in general, a difficult task due to the potential complexity of the continuous dynamics. Currently, there are different formalisms and tools which are able to analyze specific types of hybrid systems, model checking being one of the most used approaches. In this paper, we propose an extension of the discrete model checker Java Path Finder in order to analyze hybrid systems. We apply a general methodology which has been successfully used to extend SPIN. This methodology is non-intrusive, and uses external libraries, such as Parma Polyhedra Library, to abstract the continuous behavior of the hybrid system independent to the underlying model checker.

Testing Temporal Logic on Infinite Java Traces

This paper summarizes an approach for testing reactive and concurrent Java programs which combines model checking and runtime monitoring. We use a model checker for two purposes. On the one hand, it analyzes multiple program executions by generating test input parameters. On the other hand, it checks each program execution against a linear temporal logic (LTL) property. The paper presents two methods to abstract the Java states that allow efficient testing of LTL. One of this methods supports the detection of cycles to test LTL on potentially infinite Java execution traces. Runtime monitoring is used to generate the Java execution traces to be considered as input of the model checker. Our current implementation in the tool TJT uses Spin as the model checker and the Java Debug Interface (JDI) for runtime monitoring. TJT is presented as a plug-in for Eclipse and it has been successfully applied to complex public Java programs.

Timed Automata and Model Checking to Verify Business Processes

Currently, the use of Software Engineering methods has been shown to be useful in improving business modelling techniques as a result of their application to Business Process (BP)­modelling initiatives. Nowadays when the business process needs to be supported by Information Technology, the Unified Modeling Language (UML) is widely used for modelling. This paper presents the use of Timed Automata (TA) and Model Checking (MC) by their application to an example of a BP enterprise­project related to the Customer Relationship Management (CRM) business. The Uppaal tool is used in this work. With this proposal, the analysts and designers are supported in the development of the BP­task model associated with a BP design by using UML as the main modelling language. The application of the proposal is aimed at ensuring the correctness of the BP­task model with respect to the initial property specification derived from the business rules.