582 research outputs found

    Synthesis and Stochastic Assessment of Cost-Optimal Schedules

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    We present a novel approach to synthesize good schedules for a class of scheduling problems that is slightly more general than the scheduling problem FJm,a|gpr,r_j,d_j|early/tardy. The idea is to prime the schedule synthesizer with stochastic information more meaningful than performance factors with the objective to minimize the expected cost caused by storage or delay. The priming information is obtained by stochastic simulation of the system environment. The generated schedules are assessed again by simulation. The approach is demonstrated by means of a non-trivial scheduling problem from lacquer production. The experimental results show that our approach achieves in all considered scenarios better results than the extended processing times approach

    TURTLE: Four Weddings and a Tutorial

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    The paper discusses an educational case study of protocol modelling in TURTLE, a real-time UML profile supported by the open source toolkit TTool. The method associated with TURTLE is step by step illustrated with the connection set up and handover procedures defined for the Future Air navigation Systems. The paper covers the following methodological stages: requirement modeling, use-case driven and scenario based analysis, object-oriented design and rapid prototyping in Java. Emphasis is laid on the formal verification of analysis and design diagrams

    Making formal verification amenable to real-time UML practitioners

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    TTool, a real-time UML toolkit, offers user-friendly interfaces to formal verification techniques such as reachability analysis, observer-based analysis and automatic generation of traceability matrices. Those techniques are surveyed in the paper

    On Consistency of Operational Transformation Approach

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    The Operational Transformation (OT) approach, used in many collaborative editors, allows a group of users to concurrently update replicas of a shared object and exchange their updates in any order. The basic idea of this approach is to transform any received update operation before its execution on a replica of the object. This transformation aims to ensure the convergence of the different replicas of the object, even though the operations are executed in different orders. However, designing transformation functions for achieving convergence is a critical and challenging issue. Indeed, the transformation functions proposed in the literature are all revealed incorrect. In this paper, we investigate the existence of transformation functions for a shared string altered by insert and delete operations. From the theoretical point of view, two properties - named TP1 and TP2 - are necessary and sufficient to ensure convergence. Using controller synthesis technique, we show that there are some transformation functions which satisfy only TP1 for the basic signatures of insert and delete operations. As a matter of fact, it is impossible to meet both properties TP1 and TP2 with these simple signatures.Comment: In Proceedings Infinity 2012, arXiv:1302.310

    Timed Automata Semantics for Analyzing Creol

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    We give a real-time semantics for the concurrent, object-oriented modeling language Creol, by mapping Creol processes to a network of timed automata. We can use our semantics to verify real time properties of Creol objects, in particular to see whether processes can be scheduled correctly and meet their end-to-end deadlines. Real-time Creol can be useful for analyzing, for instance, abstract models of multi-core embedded systems. We show how analysis can be done in Uppaal.Comment: In Proceedings FOCLASA 2010, arXiv:1007.499

    Symbolic Model-Checking using ITS-tools

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    International audienceWe present the symbolic model-checking toolset ITS-tools. The model-checking back-end engine is based on hierarchical set decision diagrams (SDD) and supports reachability, CTL and LTL model-checking, using both classical and original algorithms. As front-end input language, we promote a Guarded Action Language (GAL), a simple yet expressive language for concurrency. Transformations from popular formalisms into GAL are provided enabling fully symbolic model-checking of third party (Uppaal, Spin, Divine...) specifications. The tool design allows to easily build your own transformation, leveraging tools from the meta-modeling community. The ITS-tools additionally come with a user friendly GUI embedded in Eclipse

    LTL Parameter Synthesis of Parametric Timed Automata

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    The parameter synthesis problem for parametric timed automata is undecidable in general even for very simple reachability properties. In this paper we introduce restrictions on parameter valuations under which the parameter synthesis problem is decidable for LTL properties. The investigated bounded integer parameter synthesis problem could be solved using an explicit enumeration of all possible parameter valuations. We propose an alternative symbolic zone-based method for this problem which results in a faster computation. Our technique extends the ideas of the automata-based approach to LTL model checking of timed automata. To justify the usefulness of our approach, we provide experimental evaluation and compare our method with explicit enumeration technique.Comment: 23 pages, extended versio
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