Jacob Illum Rasmussen

Aalborg University, Aalborg, Region North Jutland, Denmark

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Publications (19)0.77 Total impact

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    ABSTRACT: We propose a modeling framework for performing schedulability analysis by using Uppaal real-time model-checker [2]. The framework is inspired by a case study where schedulability analysis of a satellite system is performed. The framework assumes a single CPU hardware where a fixed priority preemptive scheduler is used in a combination with two resource sharing protocols and in addition voluntary task suspension is considered. The contributions include the modeling framework, its application on an industrial case study and a comparison of results with classical response time analysis. Keywordsschedulability analysis-timed automata-stop-watch automata-model-checking-verification
    11/2010: pages 175-190;
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    ABSTRACT: In this paper we present two frameworks that have been implemented to link traditional model-checking techniques to the domain of control. The techniques are based on solving a timed game and using the resulting solution (a strategy) as a controller. The obtained discrete controller must fit within its continuous environment, which is modelled and taken care of in our frameworks. Our first technique does it by using Matlab to discretise the problem and then Uppaal-tiga to solve the obtained timed game. This is implemented as a toolbox. The second technique relies on the user defining a timed game model in Uppaal-tiga. Then the strategy is automatically imported in Simulink as an S-function for simulation and validation purposes. We demonstrate the effectiveness of these frameworks in different case-studies.
    Formal Methods for Components and Objects - 9th International Symposium, FMCO 2010, Graz, Austria, November 29 - December 1, 2010. Revised Papers; 01/2010
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    Leveraging Applications of Formal Methods, Verification, and Validation - 4th International Symposium on Leveraging Applications, ISoLA 2010, Heraklion, Crete, Greece, October 18-21, 2010, Proceedings, Part II; 01/2010
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    ABSTRACT: This paper details a collaboration between Aalborg University and Novo Nordiskin developing an automatic model-based test generation tool for system testing of the graphical user interface of a medical device on an embedded platform. The tool takes as input an UML Statemachine model and generates a test suite satisfying some testing criterion, such as edge or state coverage, and converts the individual test case into a scripting language that can be automatically executed against the target. The tool has significantly reduced the time required for test construction and generation, and reduced the number of test scripts while increasing the coverage.
    FM 2009: Formal Methods, Second World Congress, Eindhoven, The Netherlands, November 2-6, 2009. Proceedings; 01/2009
  • 01/2009;
  • 01/2008;
  • Kim Guldstrand Larsen, Jacob Illum Rasmussen
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    ABSTRACT: In this paper, we prove the decidability of the minimal and maximal reachability problems for multi-priced timed automata, an extension of timed automata with multiple cost variables evolving according to given rates for each location. More precisely, we consider the problems of synthesizing the minimal and maximal costs of reaching a given target location. These problems generalize conditional optimal reachability, i.e., the problem of minimizing one primary cost under individual upper bound constraints on the remaining, secondary, costs, and the problem of maximizing the primary cost under individual lower bound constraints on the secondary costs. Furthermore, under the liveness constraint that all traces eventually reach the goal location, we can synthesize all costs combinations that can reach the goal.The decidability of the minimal reachability problem is proven by constructing a zone-based algorithm that always terminates while synthesizing the optimal cost tuples. For the corresponding maximization problem, we construct two zone-based algorithms, one with and one without the above liveness constraint. All algorithms are presented in the setting of two cost variables and then lifted to an arbitrary number of cost variables.
    Theoretical Computer Science 01/2008; · 0.49 Impact Factor
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    Jacob Illum Rasmussen, Gerd Behrmann, Kim Guldstrand Larsen
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    ABSTRACT: In this paper, we describe a new flexible framework for state space exploration based on cooperating agents. The idea is to let various agents with different search patterns explore the state space individually and communicate information about fruitful subpaths of the search tree to each other. That way very complex global search behavior is achieved with very simple local behavior. As an example agent behavior, we propose a novel anytime randomized search strategy called frustration search. The effectiveness of the framework is illustrated in the setting of priced timed automata on a number of case studies.
    Tools and Algorithms for the Construction and Analysis of Systems, 13th International Conference, TACAS 2007, Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2007 Braga, Portugal, March 24 - April 1, 2007, Proceedings; 01/2007
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    ABSTRACT: We present a complete tool chain for automatic controller synthesis using Uppaal Tiga and Simulink. The tool chain is explored using an industrial case study for climate control in a pig stable. The problem is modeled as a game, and we use Uppaal Tiga to automatically synthesize safe strategies that are transformed for input to Simulink, which is used to run simulations on the controller and generate code that can be executed in an actual pig stable provided by industrial partner Skov A/S. The model allows for guiding the synthesis process and generate different strategies that are compared through simulations.
    Formal Modeling and Analysis of Timed Systems, 5th International Conference, FORMATS 2007, Salzburg, Austria, October 3-5, 2007, Proceedings; 01/2007
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    J. I. Rasmussen, K. G. Larsen, K. Subramani
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    ABSTRACT: In this paper, we describe an approach for solving the general class of energy-optimal task graph scheduling problems using priced timed automata. We provide an efficient zone-based algorithm for minimum-cost reachability. Furthermore, we show how the simple structure of the linear programs encountered during symbolic minimum-cost reachability analysis of priced timed automata can be exploited in order to substantially improve the performance of the current algorithm. The idea is rooted in duality of linear programs and we show that each encountered linear program can be reduced to the dual problem of an instance of the min-cost flow problem. Experimental results using Uppaal show a 70–80 percent performance gain. We provide priced timed automata models for the scheduling problems and provide experimental results illustrating the potential competitiveness of our approach compared to existing approaches such as mixed integer linear programming.
    Formal Methods in System Design 06/2006; 29(1):97-114. · 0.28 Impact Factor
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    ABSTRACT: We consider timed games extended with cost information, and prove computability of the optimal cost and of "-optimal memoryless strategies in timed games with one clock. In contrast, this problem has recently been proved undecidable for timed games with three clocks.
    FSTTCS 2006: Foundations of Software Technology and Theoretical Computer Science, 26th International Conference, Kolkata, India, December 13-15, 2006, Proceedings; 01/2006
  • K. G. Larsen, J. I. Rasmussen
    01/2005;
  • Kim Guldstrand Larsen, Jacob Illum Rasmussen
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    ABSTRACT: In this paper, we prove decidability of the optimal conditional reachability problem for multi-priced timed automata, an extension of timed automata with multiple cost variables evolving according to given rates for each location. More precisely, we consider the problem of determining the minimal cost of reaching a given target state, with respect to some primary cost variable, while respecting upper bound constraints on the remaining (secondary) cost variables. Decidability is proven by constructing a zone-based algorithm that always terminates while synthesizing the optimal cost with a single secondary cost variable. The approach is then lifted to any number of secondary cost variables.
    Foundations of Software Science and Computational Structures, 8th International Conference, FOSSACS 2005, Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2005, Edinburgh, UK, April 4-8, 2005, Proceedings; 01/2005
  • Gerd Behrmann, Kim Guldstrand Larsen, Jacob Illum Rasmussen
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    ABSTRACT: This contribution reports on the considerable effort made recently towards extending and applying well-established timed automata technology to optimal scheduling and planning problems. The effort of the authors in this direction has to a large extent been carried out as part of the European projects VHS [20] and AMETIST [16] and are available in the recently released UPPAAL CORA [12], a variant of the real-time verification tool UPPAAL [18, 5] specialized for cost-optimal reachability for the extended model of so-called priced timed automata.
    SIGMETRICS Performance Evaluation Review. 01/2005; 32:34-40.
  • Gerd Behrmann, Kim Guldstrand Larsen, Jacob Illum Rasmussen
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    ABSTRACT: In this paper, we deal with the problem of parameter synthesis for a subset of parameterised TCTL over timed automata. The problem was proved decidable by V. Bruyere et al. in [10] for general parameterised TCTL using a translation to Presburger arithmetic and also considered by F. Wang in [13] using a parametric region construction. In contrast, we provide two efficient zone based algorithms for a useful subset of parameterised TCTL. The subset has obvious applications to worst case execution time (WCET) analysis. In [11] WCET is performed via model checking, but their approach uses a binary search strategy over several invocations of the model checker. In contrast, both our algorithms synthesise the bound directly. We provide experimental results based on a prototype implementation in Uppaal for two case studies: The first concerns response time analysis of a well known train gate scenario. The second is an execution time analysis of task graph problems where tasks have uncertain execution times.
    Formal Modeling and Analysis of Timed Systems, Third International Conference, FORMATS 2005, Uppsala, Sweden, September 26-28, 2005, Proceedings; 01/2005
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    Gerd Behrmann, Kim Guldstrand Larsen, Jacob Illum Rasmussen
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    ABSTRACT: This contribution reports on the considerable effort made re- cently towards extending and applying well-established timed automata technology to optimal scheduling and planning problems. The effort of the authors in this direction has to a large extent been carried out as part of the European projects Vhs (22) and Ametist (17) and are available in the recently released Uppaal Cora (12), a variant of the real-time verification tool Uppaal (20,5) specialized for cost-optimal reachability for the extended model of priced timed automata.
    Formal Methods for Components and Objects, Third International Symposium, FMCO 2004, Leiden, The Netherlands, November 2 - 5, 2004, Revised Lectures; 01/2004
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    Jacob Illum Rasmussen, Kim Guldstrand Larsen, K. Subramani
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    ABSTRACT: In this paper, we show how the simple structure of the linear programs encountered during symbolic minimum-cost reachability analysis of priced timed automata can be exploited in order to substantially improve the performance of the current algorithm. The idea is rooted in duality of linear programs and we show that each encountered linear program can be reduced to the dual problem of an instance of the min-cost flow problem. Thus, we only need to solve instances of the much simpler min-cost flow problem during minimum-cost reachability analysis. Experimental results using Uppaal show a 70-80 percent performance gain. As a main application area, we show how to solve energy-optimal task graph scheduling problems using the framework of priced timed automata.
    Tools and Algorithms for the Construction and Analysis of Systems, 10th International Conference, TACAS 2004, Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2004, Barcelona, Spain, March 29 - April 2, 2004, Proceedings; 01/2004
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    ABSTRACT: In this paper, we consider priced (or weighted) timed au-tomata, and prove various decidability results when the au-tomaton has only one clock: we prove that model check-ing of WCTL is decidable and that optimal costs in priced timed games are computable. In contrast, it has recently been proved that these problems are undecidable for this model as soon as the system has three clocks.
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    Georgeta Igna, Jacob Illum Rasmussen, Kim G Larsen, Frits W Vaandrager
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    ABSTRACT: Design space exploration is a common approach to improve the performance of distributed embedded systems. Some characteristics like hardware capacity can easily be explored by changing some parameters in the model and re-running the experiments. However, searching for improvements of scheduling rules is not that straightforward. It is difficult to find generic and simple scheduling rules which ensure a high performance of the system for all its possible applications. Usually, one rule is more favorable for one category of applications but disadvantaging others. We describe an approach to explore the design space of a soft realtime embedded system using timed automata model checking. The system studied consists of the system architecture of an Océ printer and the concurrent programmed paths which data can take on it. We consider the system in an overloaded state (memory full, many files in the system) and search for improvements of the existing scheduling rules. We also indicate the pros and cons of this analysis technique for our case study.