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  • 1.
    Atif, Yacine
    et al.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Al-Falahi, Kanna
    College of Information Technology, United Arab Emirates University, Al-Ain, United Arab Emirates.
    Wangchuk, Tshering
    Royal Institute of Management, Thimphu, Bhutan.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    A fuzzy logic approach to influence maximization in social networks2020In: Journal of Ambient Intelligence and Humanized Computing, ISSN 1868-5137, E-ISSN 1868-5145, Vol. 11, no 6, p. 2435-2451Article in journal (Refereed)
    Abstract [en]

    Within a community, social relationships are paramount to profile individuals’ conduct. For instance, an individual within a social network might be compelled to embrace a behaviour that his/her companion has recently adopted. Such social attitude is labelled social influence, which assesses the extent by which an individual’s social neighbourhood adopt that individual’s behaviour. We suggest an original approach to influence maximization using a fuzzy-logic based model, which combines influence-weights associated with historical logs of the social network users, and their favourable location in the network. Our approach uses a two-phases process to maximise influence diffusion. First, we harness the complexity of the problem by partitioning the network into significantly-enriched community-structures, which we then use as modules to locate the most influential nodes across the entire network. These key users are determined relatively to a fuzzy-logic based technique that identifies the most influential users, out of which the seed-set candidates to diffuse a behaviour or an innovation are extracted following the allocated budget for the influence campaign. This way to deal with influence propagation in social networks, is different from previous models, which do not compare structural and behavioural attributes among members of the network. The performance results show the validity of the proposed partitioning-approach of a social network into communities, and its contribution to “activate” a higher number of nodes overall. Our experimental study involves both empirical and real contemporary social-networks, whereby a smaller seed set of key users, is shown to scale influence to the high-end compared to some renowned techniques, which employ a larger seed set of key users and yet they influence less nodes in the social network.

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  • 2.
    Atif, Yacine
    et al.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Ding, Jianguo
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Jeusfeld, Manfred
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Yuning, Jiang
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Brax, Christoffer
    CombiTech AB, Skövde, Sweden.
    Gustavsson, Per M.
    CombiTech AB, Skövde, Sweden.
    Cyber-Threat Intelligence Architecture for Smart-Grid Critical Infrastructures Protection2017Conference paper (Refereed)
    Abstract [en]

    Critical infrastructures (CIs) are becoming increasingly sophisticated with embedded cyber-physical systems (CPSs) that provide managerial automation and autonomic controls. Yet these advances expose CI components to new cyber-threats, leading to a chain of dysfunctionalities with catastrophic socio-economical implications. We propose a comprehensive architectural model to support the development of incident management tools that provide situation-awareness and cyber-threats intelligence for CI protection, with a special focus on smart-grid CI. The goal is to unleash forensic data from CPS-based CIs to perform some predictive analytics. In doing so, we use some AI (Artificial Intelligence) paradigms for both data collection, threat detection, and cascade-effects prediction. 

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  • 3.
    Atif, Yacine
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Jiang, Yuning
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Jeusfeld, Manfred A.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Ding, Jianguo
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Brax, Christoffer
    Combitech.
    Haglund, Daniel
    Combitech.
    Lindström, Björn
    Combitech.
    Cyber-threat analysis for Cyber-Physical Systems: Technical report for Package 4, Activity 3 of ELVIRA project2018Report (Other academic)
    Abstract [en]

    Smart grid employs ICT infrastructure and network connectivity to optimize efficiency and deliver new functionalities. This evolu- tion is associated with an increased risk for cybersecurity threats that may hamper smart grid operations. Power utility providers need tools for assessing risk of prevailing cyberthreats over ICT infrastructures. The need for frameworks to guide the develop- ment of these tools is essential to define and reveal vulnerability analysis indicators. We propose a data-driven approach for design- ing testbeds to evaluate the vulnerability of cyberphysical systems against cyberthreats. The proposed framework uses data reported from multiple components of cyberphysical system architecture layers, including physical, control, and cyber layers. At the phys- ical layer, we consider component inventory and related physi- cal flows. At the control level, we consider control data, such as SCADA data flows in industrial and critical infrastructure control systems. Finally, at the cyber layer level, we consider existing secu- rity and monitoring data from cyber-incident event management tools, which are increasingly embedded into the control fabrics of cyberphysical systems.

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  • 4.
    Atif, Yacine
    et al.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Jiang, Yuning
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Ding, Jianguo
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Jeusfeld, Manfred
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Andler, Sten
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Nero, Eva
    Combitech, Sweden.
    Brax, Christoffer
    Combitech, Sweden.
    Haglund, Daniel
    Combitech, Sweden.
    Multi-agent Systems for Power Grid Monitoring: Technical report for Package 4.1 of ELVIRA project2018Report (Other academic)
    Abstract [en]

    This document reports a technical description of ELVIRA project results obtained as part of Work- package 4.1 entitled “Multi-agent systems for power Grid monitoring”. ELVIRA project is a collaboration between researchers in School of IT at University of Skövde and Combitech Technical Consulting Company in Sweden, with the aim to design, develop and test a testbed simulator for critical infrastructures cybersecurity. This report outlines intelligent approaches that continuously analyze data flows generated by Supervisory Control And Data Acquisition (SCADA) systems, which monitor contemporary power grid infrastructures. However, cybersecurity threats and security mechanisms cannot be analyzed and tested on actual systems, and thus testbed simulators are necessary to assess vulnerabilities and evaluate the infrastructure resilience against cyberattacks. This report suggests an agent-based model to simulate SCADA- like cyber-components behaviour when facing cyber-infection in order to experiment and test intelligent mitigation mechanisms. 

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  • 5.
    Ding, Jianguo
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Atif, Yacine
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Jeusfeld, Manfred
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    CPS-based Threat Modeling for Critical Infrastructure Protection2017In: Performance Evaluation Review, ISSN 0163-5999, E-ISSN 1557-9484, Vol. 45, no 2, p. 129-132Article in journal (Refereed)
    Abstract [en]

    Cyber-Physical Systems (CPSs) are augmenting traditionalCritical Infrastructures (CIs) with data-rich operations. Thisintegration creates complex interdependencies that exposeCIs and their components to new threats. A systematicapproach to threat modeling is necessary to assess CIs’ vulnerabilityto cyber, physical, or social attacks. We suggest anew threat modeling approach to systematically synthesizeknowledge about the safety management of complex CIs andsituational awareness that helps understanding the nature ofa threat and its potential cascading-effects implications.

  • 6.
    Ding, Jianguo
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Mathiason, Gunnar
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Towards Threat Modeling for CPS-based Critical Infrastructure Protection2015In: Proceedings of the International Emergency Management Society (TIEMS), 22nd TIEMS Annual Conference: Evolving threats and vulnerability landscape: new challenges for the emergency management / [ed] Snjezana Knezic & Meen Poudyal Chhetri, Brussels: TIEMS, The International Emergency Management Society , 2015, Vol. 22Conference paper (Refereed)
    Abstract [en]

    With the evolution of modern Critical Infrastructures (CI), more Cyber-Physical systems are integrated into the traditional CIs. This makes the CIs a multidimensional complex system, which is characterized by integrating cyber-physical systems into CI sectors (e.g., transportation, energy or food & agriculture). This integration creates complex interdependencies and dynamics among the system and its components. We suggest using a model with a multi-dimensional operational specification to allow detection of operational threats. Embedded (and distributed) information systems are critical parts of the CI where disruption can lead to serious consequences. Embedded information system protection is therefore crucial. As there are many different stakeholders of a CI, comprehensive protection must be viewed as a cross-sector activity to identify and monitor the critical elements, evaluate and determine the threat, and eliminate potential vulnerabilities in the CI. A systematic approach to threat modeling is necessary to support the CI threat and vulnerability assessment. We suggest a Threat Graph Model (TGM) to systematically model the complex CIs. Such modeling is expected to help the understanding of the nature of a threat and its impact on throughout the system. In order to handle threat cascading, the model must capture local vulnerabilities as well as how a threat might propagate to other components. The model can be used for improving the resilience of the CI by encouraging a design that enhances the system's ability to predict threats and mitigate their damages. This paper surveys and investigates the various threats and current approaches to threat modeling of CI. We suggest integrating both a vulnerability model and an attack model, and we incorporate the interdependencies within CI cross CI sectors. Finally, we present a multi-dimensional threat modeling approach for critical infrastructure protection.

  • 7.
    Eriksson, Anders
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre. Saab Aeronautics, Linköping, Sweden.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    UML Associations: Reducing the gap in test coverage between model and code2016In: Proceedings of the 4th International Conference on Model-Driven Engineering and Software Development / [ed] Slimane Hammoudi, Luis Ferreira Pires, Bran Selic & Philippe Desfray, SciTePress, 2016, Vol. 1, p. 589-599Conference paper (Refereed)
    Abstract [en]

    This paper addresses the overall problem of estimating the quality of a test suite when testing is performed at aplatform-independent level, using executable UML models. The problem is that the test suite is often requiredto fulfill structural code coverage criteria. In the avionics domain it is usually required that the tests achieve100% coverage according to logic-based coverage criteria. Such criteria are less effective when applied toexecutable UML models than when they are applied to code because the action code found in such modelscontains conditions in navigation and loops that are not explicit and therefore not captured by logic-basedcoverage criteria. We present two new coverage criteria for executable UML models, and we use an industrialapplication from the avionics domain to show that these two criteria should be combined with a logic-basedcriterion when testing the executable UML model. As long as the coverage is less than 100% at the modellevel, there is no point in running the tests at the code level since all functionality of the model is not yet tested,and this is necessary to achieve 100% coverage at the code level.

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  • 8.
    Eriksson, Anders
    et al.
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Lindström, Birgitta
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Andler, Sten F.
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Offutt, Jeff
    Software Engineering, George Mason University, Fairfax, VA 22030-4444, United States.
    Model transformation impact on test artifacts: An empirical study2012In: Proceedings of the Workshop on Model-Driven Engineering, Verification and Validation, MoDeVVa 2012, Association for Computing Machinery (ACM), 2012, p. 5-10Conference paper (Refereed)
    Abstract [en]

    Development environments that support Model-Driven Development often focus on model-level functional testing, enabling verification of design models against their specifications. However, developers of safety-critical software systems are also required to show that tests cover the structure of the implementation. Unfortunately, the implementation structure can diverge from the model depending on choices such as the model compiler or target language. Therefore, structural coverage at the model level may not guarantee coverage of the implementation. We present results from an industrial experiment that demonstrates the model-compiler effect on test artifacts in xtUML models when these models are transformed into C++. Test artifacts, i.e., predicates and clauses, are used to satisfy the structural code coverage criterion, in this case MCDC, which is required by the US Federal Aviation Administration. The results of the experiment show not only that the implementation contains more test artifacts than the model, but also that the test artifacts can be deterministically enumerated during translation. The analysis identifies two major sources for these additional test artifacts. © 2012 ACM.

  • 9.
    Eriksson, Anders
    et al.
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre. Saab Aeronautics, Linköping, Sweden.
    Lindström, Birgitta
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Offutt, Jeff
    Software Engineering, George Mason University, Fairfax, VA 22030-4444, United States.
    Transformation rules for platform independent testing: An empirical study2013In: Proceedings of the Sixth IEEE International Conference on Software Testing, Verification and Validation, ICST 2013, IEEE conference proceedings, 2013, p. 202-211Conference paper (Refereed)
    Abstract [en]

    Most Model-Driven Development projects focus on model-level functional testing. However, our recent study found an average of 67% additional logic-based test requirements from the code compared to the design model. The fact that full coverage at the design model level does not guarantee full coverage at the code level indicates that there are semantic behaviors in the model that model-based tests might miss, e.g., conditional behaviors that are not explicitly expressed as predicates and therefore not tested by logic-based coverage criteria. Avionics standards require that the structure of safety critical software is covered according to logic-based coverage criteria, including MCDC for the highest safety level. However, the standards also require that each test must be derived from the requirements. This combination makes designing tests hard, time-consuming and expensive to design. This paper defines a new model that uses transformation rules to help testers define tests at the platform independent model level. The transformation rules have been applied to six large avionic applications. The results show that the new model reduced the difference between model and code with respect to the number of additional test requirements from an average of67% to 0% in most cases and less than 1% for all applications. © 2013 IEEE.

  • 10.
    González-Hernández, Loreto
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Offutt, Jeff
    George Mason University, USA.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Potena, Pasqualina
    RISE SICS, Västerås.
    Bohlin, Markus
    RISE SICS, Västerås.
    Using Mutant Stubbornness to Create Minimal and Prioritized Test Sets2018In: 2018 IEEE International Conference on Software Quality, Reliability and Security (QRS), IEEE Computer Society, 2018, p. 446-457Conference paper (Refereed)
    Abstract [en]

    In testing, engineers want to run the most useful tests early (prioritization). When tests are run hundreds or thousands of times, minimizing a test set can result in significant savings (minimization). This paper proposes a new analysis technique to address both the minimal test set and the test case prioritization problems. This paper precisely defines the concept of mutant stubbornness, which is the basis for our analysis technique. We empirically compare our technique with other test case minimization and prioritization techniques in terms of the size of the minimized test sets and how quickly mutants are killed. We used seven C language subjects from the Siemens Repository, specifically the test sets and the killing matrices from a previous study. We used 30 different orders for each set and ran every technique 100 times over each set. Results show that our analysis technique performed significantly better than prior techniques for creating minimal test sets and was able to establish new bounds for all cases. Also, our analysis technique killed mutants as fast or faster than prior techniques. These results indicate that our mutant stubbornness technique constructs test sets that are both minimal in size, and prioritized effectively, as well or better than other techniques.

  • 11.
    Grindal, Mats
    et al.
    University of Skövde, School of Humanities and Informatics.
    Lindström, Birgitta
    University of Skövde, School of Humanities and Informatics.
    Offutt, Jeff
    University of Skövde, School of Humanities and Informatics.
    Andler, Sten F
    University of Skövde, School of Humanities and Informatics.
    An Evaluation of Combination Strategies for Test Case Selection2003Report (Other academic)
    Abstract [en]

    In this report we present the results from a comparative evaluation of five combination strategies. Combination strategies are test case selection methods that combine interesting values of the input parameters of a test object to form test cases. One of the investigated combination strategies, namely the Each Choice strategy, satisfies 1-wise coverage, i.e., each interesting value of each parameter is represented at least once in the test suite. Two of the strategies, the Orthogonal Arrays and Heuristic Pair-Wise strategies both satisfy pair-wise coverage, i.e., every possible pair of interesting values of any two parameters are included in the test suite. The fourth combination strategy, the All Values strategy, generates all possible combinations of the interesting values of the input parameters. The fifth and last combination strategy, the Base Choice combination strategy, satisfies 1-wise coverage but in addition makes use of some semantic information to construct the test cases.

    Except for the All Values strategy, which is only used as a reference point with respect to the number of test cases, the combination strategies are evaluated and compared with respect to number of test cases, number of faults found, test suite failure density, and achieved decision coverage in an experiment comprising five programs, similar to Unix commands, seeded with 131 faults. As expected, the Each Choice strategy finds the smallest number of faults among the evaluated combination strategies. Surprisingly, the Base Choice strategy performs as well, in terms of detecting faults, as the pair-wise combination strategies, despite fewer test cases. Since the programs and faults in our experiment may not be representative of actual testing problems in an industrial setting, we cannot draw any general conclusions regarding the number of faults detected by the evaluated combination strategies. However, our analysis shows some properties of the combination strategies that appear significant in spite of the programs and faults not being representative. The two most important results are that the Each Choice strategy is unpredictable in terms of which faults will be detected, i.e., most faults found are found by chance, and that the Base Choice and the pair-wise combination strategies to some extent target different types of faults.

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    FULLTEXT01
  • 12.
    Grindal, Mats
    et al.
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Lindström, Birgitta
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Offutt, Jeff
    George Mason Univ, Dept Informat & Software Engn, Fairfax, VA 22030 USA.
    Andler, Sten F.
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    An Evaluation of Combination Strategies for Test Case Selection2006In: Empirical Software Engineering, ISSN 1382-3256, E-ISSN 1573-7616, Vol. 11, no 4, p. 583-611Article in journal (Refereed)
    Abstract [en]

    This paper presents results from a comparative evaluation of five combination strategies. Combination strategies are test case selection methods that combine “interesting” values of the input parameters of a test subject to form test cases. This research comparatively evaluated five combination strategies; the All Combination strategy (AC), the Each Choice strategy (EC), the Base Choice strategy (BC), Orthogonal Arrays (OA) and the algorithm from the Automatic Efficient Test Generator (AETG). AC satisfies n-wise coverage, EC and BC satisfy 1-wise coverage, and OA and AETG satisfy pair-wise coverage. The All Combinations strategy was used as a “gold standard” strategy; it subsumes the others but is usually too expensive for practical use. The others were used in an experiment that used five programs seeded with 128 faults. The combination strategies were evaluated with respect to the number of test cases, the number of faults found, failure size, and number of decisions covered. The strategy that requires the least number of tests, Each Choice, found the smallest number of faults. Although the Base Choice strategy requires fewer test cases than Orthogonal Arrays and AETG, it found as many faults. Analysis also shows some properties of the combination strategies that appear significant. The two most important results are that the Each Choice strategy is unpredictable in terms of which faults will be revealed, possibly indicating that faults are found by chance, and that the Base Choice and the pair-wise combination strategies to some extent target different types of faults.

  • 13.
    Hassan, Mohammad Mahdi
    et al.
    Karlstad University, Sweden.
    Afzal, Wasif
    Mälardalen University, Sweden.
    Blom, Martin
    Karlstad University, Sweden.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Andler, Sten F.
    University of Skövde, The Informatics Research Centre. University of Skövde, School of Informatics.
    Eldh, Sigrid
    Ericsson AB, Sweden.
    Testability and Software Robustness: A Systematic Literature Review2015In: Proceedings 41st Euromicro Conference on Software Engineering and Advanced Applications SEAA 2015, IEEE Computer Society, 2015, p. 341-348Conference paper (Refereed)
  • 14.
    Hassan, Mohammad Mahdi
    et al.
    Karlstad University, Sweden.
    Afzal, Wasif
    Mälardalen University, Sweden.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Shah, Syed Muhammad Ali
    SICS, Sweden.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Blom, Martin
    Karlstad University, Sweden.
    Testability and Software Performance: A Systematic Mapping Study2016In: SAC '16: Proceedings of the 31st Annual ACM Symposium on Applied Computing April 2016, New York, NY: Association for Computing Machinery (ACM), 2016, p. 1566-1569Conference paper (Refereed)
    Abstract [en]

    In most of the research on software testability, functional correctness of the software has been the focus while the evidence regarding testability and non-functional properties such as performance is sporadic. The objective of this study is to present the current state-of-the-art related to issues of importance, types and domains of software under test, types of research, contribution types and design evaluation methods concerning testability and software performance. We find that observability, controllability and testing effort are the main testability issues while timeliness and response time (i.e., time constraints) are the main performance issues in focus. The primary studies in the area use diverse types of software under test within different domains, with realtime systems as being a dominant domain. The researchers have proposed many different methods in the area, however these methods lack implementation in practice.

  • 15.
    Jiang, Yuning
    et al.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Ding, Jianguo
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Atif, Yacine
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Jeusfeld, Manfred
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Andler, Sten
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Brax, Christoffer
    Combitech, Sweden.
    Haglund, Daniel
    Combitech, Sweden.
    Complex Dependencies Analysis: Technical Description of Complex Dependencies in Critical Infrastructures, i.e. Smart Grids. Work Package 2.1 of the ELVIRA Project2018Report (Other academic)
    Abstract [en]

    This document reports a technical description of ELVIRA project results obtained as part of Work-package 2.1 entitled “Complex Dependencies Analysis”. In this technical report, we review attempts in recent researches where connections are regarded as influencing factors to  IT systems monitoring critical infrastructure, based on which potential dependencies and resulting disturbances are identified and categorized. Each kind of dependence has been discussed based on our own entity based model. Among those dependencies, logical and functional connections have been analysed with more details on modelling and simulation techniques.

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    ELVIRA_2.1-HS-IIT-TR-18-003.Complex-Dependencies-Analysis
  • 16.
    Lindström, Birgitta
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Testability of Dynamic Real-Time Systems2009Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This dissertation concerns testability of event-triggered real-time systems. Real-time systems are known to be hard to test because they are required to function correct both with respect to what the system does and when it does it. An event-triggered real-time system is directly controlled by the events that occur in the environment, as opposed to a time-triggered system, which behavior with respect to when the system does something is constrained, and therefore more predictable. The focus in this dissertation is the behavior in the time domain and it is shown how testability is affected by some factors when the system is tested for timeliness. This dissertation presents a survey of research that focuses on software testability and testability of real-time systems. The survey motivates both the view of testability taken in this dissertation and the metric that is chosen to measure testability in an experiment. We define a method to generate sets of traces from a model by using a meta algorithm on top of a model checker. Defining such a method is a necessary step to perform the experiment. However, the trace sets generated by this method can also be used by test strategies that are based on orderings, for example execution orders. An experimental study is presented in detail. The experiment investigates how testability of an event-triggered real-time system is affected by some constraining properties of the execution environment. The experiment investigates the effect on testability from three different constraints regarding preemptions, observations and process instances. All of these constraints were claimed in previous work to be significant factors for the level of testability. Our results support the claim for the first two of the constraints while the third constraint shows no impact on the level of testability. Finally, this dissertation discusses the effect on the event-triggered semantics when the constraints are applied on the execution environment. The result from this discussion is that the first two constraints do not change the semantics while the third one does. This result indicates that a constraint on the number of process instances might be less useful for some event-triggered real-time systems.

     

     

  • 17.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Offutt, Jeff
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre. George Mason University, Fairfax VA, USA.
    Pettersson, Paul
    Mälardalen University, Västerås, Sweden.
    Sundmark, Daniel
    Swedish Institute of Computer Science, Kista, Sweden.
    Mutating Aspect-Oriented Models to Test Cross-Cutting Concerns2015In: 2015 IEEE 8th International Conference on Software Testing, Verification and Validation Workshops, ICSTW 2015 - Proceedings, IEEE conference proceedings, 2015, p. Article number 7107456-Conference paper (Refereed)
  • 18.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Humanities and Informatics.
    Grindal, Mats
    University of Skövde, School of Humanities and Informatics.
    Offutt, Jeff
    George Mason University, Fairfax, VA, USA.
    Using an Existing Suite of Test Objects: Experience from a Testing Experiment2004In: ACM SIGSOFT Software Engineering Notes: SECTION: Workshop on empirical research in software testing papers, 2004, Vol. 29, p. 1-3Conference paper (Other academic)
    Abstract [en]

    This workshop paper presents lessons learned from a recent experiment to compare several test strategies. The test strategies were compared in terms of the number of tests needed to satisfy them and in terms of faults found. The experimental design and conduct are discussed, and frank assessments of the decisions that were made are provided. The paper closes with a summary of the lessons that were learned.

  • 19.
    Lindström, Birgitta
    et al.
    University of Skövde, Department of Computer Science.
    Mellin, Jonas
    University of Skövde, Department of Computer Science.
    Andler, Sten F.
    University of Skövde, Department of Computer Science.
    Testability of dynamic real-time systems2002In: Proceedings of Eigth International Conference on Real-Time Computing Systems and Applications (RTCSA2002), 2002, p. 93-97Conference paper (Refereed)
  • 20.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Márki, András
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    On redundant mutants and strong mutation2015Report (Other academic)
    Abstract [en]

    This study evaluates a theory of subsumption relations among mutants created by the ROR mutation operator, thus making most of these mutants redundant. A redundant mutant can be skipped during mutation analysis without decreasing the quality of the resulting test suite. This theory is interesting since mutation testing is computationally expensive and the theory states that the set of ROR mutants can be reduced by 57%. The reduced set of ROR mutants has therefore, been used in several recent studies. However, we provide proof that this theory do not hold for strong mutation and that part of the theory is incorrect. The theory itself has to our knowledge, never before been evaluated empirically.

    By finding counter examples, we prove that a test suite, which is 100% adequate for the non-redundant ROR mutants might not be 100% adequate for the mutants, which are supposed to be redundant. The subsumption relations do not hold for strong mutation. We have also proved that more than one top-level mutant can be detected by the same test. This should not be possible according to the theory. Hence, this part of the theory is incorrect, independent of strong or weak mutation.

    Our findings are important since strong mutation is frequently used to evaluate test suites and testing criteria. Just as redundant mutants can give an overestimation of the mutation score for a test suite, using the reduced set can give an underestimation. Results reported from such studies should therefore, be accompanied by information on whether the reduced or complete set of ROR was used and if the researchers used strong or weak mutation.

  • 21.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Márki, András
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    On Strong Mutation and Subsuming Mutants2016In: Proceedings: 2016 IEEE International Conference on Software Testing, Verification and Validation Workshops, IEEE Computer Society, 2016, p. 112-121Conference paper (Refereed)
    Abstract [en]

    Mutation analysis is a powerful technique for software testing but it is also known to be computationally expensive.The main reason for the high computational cost is that many of themutants are redundant and thus, do not contribute to the quality of the test suite. One of the most promising approaches toavoid producing redundant mutants is to identify subsumption relations among mutants, preferably before these are generated.Such relations have for example, been identified at an operator level for mutants created by the ROR operator. This reduced set of non-redundant mutants hasbeen used in several recent studies and is also the default option in at least one mutation testing tool that supports strong mutation. This raises questions on whether the identified subsumption relations between the mutants hold in a context ofstrong mutation or variants of weak mutation that require some limited error propagation (firm mutation).

    We have conducted an experimental study to investigate the subsumption relations in the context of strong or firm mutation.We observed that it is possible to create a test suite that is 100\% adequate for the reduced set of mutants while not being 100\% adequate for the complete set. This shows that the subsumption relations do not hold for strong or firm mutation. We provide several examples on this behavior and discuss the root causes. Our findings are important since strong and firm mutation both are frequently used to evaluate test suites and testing criteria. The choice of whether to use a reduced set of mutants or an entire set should however, not be made without consideration of the context in which they are used (i.e., strong, firm or weak mutation) since the subsumption relations between ROR mutants do not hold for strong or firm mutation.Just as redundant mutants can give an overestimation of the mutation score for a test suite, using the reduced set of mutantscan give an underestimation if used together with strong or firm mutation. Results reported from such studies should therefore, be accompanied by information on whether the reduced or complete set of mutants was used and if the researchers used strong, firm or weak mutation.

  • 22.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Márki, András
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    On strong mutation and the theory of subsuming logic‐based mutants2019In: Software testing, verification & reliability, ISSN 0960-0833, E-ISSN 1099-1689, Vol. 29, no 1-2 Special Issue: SI, p. 1-23, article id e1667Article in journal (Refereed)
    Abstract [en]

    Redundant mutants might cause problems when benchmarking since testing techniques can get high scores without detecting any nonredundant mutants. However, removing nonredundant mutants might cause similar problems. Subsumed mutants are per definition also redundant since no additional tests are required to detect them once all other mutants are detected. We focus on relational operator replacement (ROR) and conditional operator replacement mutants. Subsumption relations between ROR mutants are defined by fault hierarchies. The fault hierarchies are proven for weak mutation but have since they were published been used with strong mutation. We prove that ROR fault hierarchies do not hold for strong mutation and show why. We also show that the probability for a random test to experience the problem can be more than 30% and that 50% of the mutants might be affected in a real software system. Finally, we show that there is a similar problem with the theory on sufficient conditional operator replacement.

  • 23.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Humanities and Informatics.
    Nilsson, Robert
    University of Skövde, School of Humanities and Informatics.
    Ericsson, AnnMarie
    University of Skövde, School of Humanities and Informatics.
    Grindal, Mats
    University of Skövde, School of Humanities and Informatics.
    Andler, Sten F.
    University of Skövde, School of Humanities and Informatics.
    Eftring, Bengt
    University of Skövde, School of Humanities and Informatics.
    Offutt, Jeff
    George Mason University, Fairfax, VA, USA.
    Six Issues in Testing Event-Triggered Real-Time Systems2007Report (Other academic)
    Abstract [en]

    Verification of real-time systems is a complex task, with problems coming from issues like concurrency. A previous paper suggested dealing with these problems by using a time-triggered design, which gives good support both for testing and formal analysis. However, a

    time-triggered solution is not always feasible and an event-triggered design is needed. Event-triggered systems are far more difficult to test than time-triggered systems.

    This paper revisits previously identified testing problems from a new perspective and identifies additional problems for event-triggered systems. The paper also presents an approach to deal with these problems. The TETReS project assumes a model-driven development

    process. We combine research within three different fields: (i) transformation of rule sets between timed automata specifications and ECA rules with maintained semantics, (ii) increasing testability in event-triggered system, and (iii) development of test case generation methods for event-triggered systems.

    Download full text (pdf)
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  • 24.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Offutt, Jeff
    George Mason University, Fairfax, VA, USA.
    Andler, Sten F.
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Testability of Dynamic Real-Time Systems: An Empirical Study of Constrained Execution Environment Implications2008In: Proceedings of the First International Conference on Software Testing, Verification and Validation: ICST 2008, Los Alamitos: IEEE Computer Society, 2008, p. 112-120Conference paper (Refereed)
    Abstract [en]

    Real-time systems must respond to events in a timely fashion; in hard real-time systems the penalty for a missed deadline is high. It is therefore necessary to design hard real-time systems so that the timing behavior of the tasks can be predicted. Static real-time systems have prior knowledge of the worst-case arrival patterns and resource usage. Therefore, a schedule can be calculated off-line and tasks can be guaranteed to have sufficient resources to complete (resource adequacy). Dynamic real-time systems, on the other hand, do not have such prior knowledge, and therefore must react to events when they occur. They also must adapt to changes in the urgencies of various tasks, and fairly allocate resources among the tasks. A disadvantage of static real-time systems is that a requirement on resource adequacy makes them expensive and often impractical. Dynamic realtime systems, on the other hand, have the disadvantage of being less predictable and therefore difficult to test. Hence, in dynamic systems, timeliness is hard to guarantee and reliability is often low. Using a constrained execution environment, we attempt to increase the testability of such systems. An initial step is to identify factors that affect testability. We present empirical results on how various factors in the execution environment impacts testability of real-time systems. The results show that some of the factors, previously identified as possibly impacting testability, do not have an impact, while others do.

  • 25.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Offutt, Jeff
    George Mason University, United States.
    Baral, Kesina
    George Mason University, United States.
    Márki, András
    University of Skövde, School of Informatics. University of Skövde, Informatics Research Environment.
    Message from the TestEd 2020 Chairs2020In: 2020 IEEE 13th International Conference on Software Testing, Verification and Validation Workshops: 23–27 March 2020 Porto, Portugal, IEEE, 2020, article id 9155714Conference paper (Other academic)
  • 26.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Offutt, Jeff
    George Mason University, USA.
    González-Hernández, Loreto
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Identifying Useful Mutants to Test Time Properties2018In: 2018 IEEE International Conference on Software Testing, Verification and Validation Workshops (ICSTW), IEEE Computer Society, 2018, p. 69-76Conference paper (Refereed)
    Abstract [en]

    Real-time systems have to be verified and tested for timely behavior as well as functional behavior. Thus, time is an extra dimension that adds to the complexity of software testing. A timed automata model with a model-checker can be used to generate timed test traces. To properly test the timely behavior, the set of test traces should challenge the different time constraints in the model. This paper describes and adapts mutation operators that target such time constraints in timed automata models. Time mutation operators apply a delta to the time constraints to help testers design tests that exceed the time constraints. We suggest that the size of this delta determines how easy the mutant is to kill and that the optimal delta varies by the program, mutation operator, and the individual mutant. To avoid trivial and equivalent time mutants, the delta should be set individually for each mutant. We discuss mutant subsumption and define the problem of finding dominator mutants in this new domain. In this position paper, we outline an iterative tuning process where a statistical model-checker, UPPAAL SMC, is used to: (i) create a tuned set of dominator time mutants, and (ii) generate test traces that kill the mutants.

  • 27.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Offutt, Jeff
    George Mason University, Fairfax VA, USA.
    Sundmark, Daniel
    Swedish Institute of Computer Science, Kista, Sweden.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Pettersson, Paul
    Mälardalen University, Västerås, Sweden.
    Using mutation to design tests for aspect-oriented models2017In: Information and Software Technology, ISSN 0950-5849, E-ISSN 1873-6025, Vol. 81, p. 112-130Article in journal (Refereed)
    Abstract [en]

    Abstract Context: Testing for properties such as robustness or security is complicated because their concerns are often repeated in many locations and muddled with the normal code. Such “cross-cutting concerns” include things like interrupt events, exception handling, and security protocols. Aspect-oriented (AO) modeling allows developers to model the cross-cutting behavior independently of the normal behavior, thus supporting model-based testing of cross-cutting concerns. However, mutation operators defined for AO programs (source code) are usually not applicable to AO models (AOMs) and operators defined for models do not target the AO features. Objective: We present a method to design abstract tests at the aspect-oriented model level. We define mutation operators for aspect-oriented models and evaluate the generated mutants for an example system. Method: AOMs are mutated with novel operators that specifically target the AO modeling features. Test traces killing these mutant models are then generated. The generated and selected traces are abstract tests that can be transformed to concrete black-box tests and run on the implementation level, to evaluate the behavior of the woven cross-cutting concerns (combined aspect and base models). Results: This paper is a significant extension of our paper at Mutation 2015. We present a complete fault model, additional mutation operators, and a thorough analysis of the mutants generated for an example system. Conclusions: The analysis shows that some mutants are stillborn (syntactically illegal) but none is equivalent (exhibiting the same behavior as the original model). Additionally, our AOM-specific mutation operators can be combined with pre-existing operators to mutate code or models without any overlap.

  • 28.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Humanities and Informatics.
    Pettersson, Paul
    Uppsala University.
    Model-Checking with Insufficient Memory Resources2006Report (Other academic)
    Abstract [en]

    Resource limitations is a major problem in model checking. Space and time requirements of model-checking algorithms grow exponentially with respect to the number of variables and parallel automata of the analyzed model. We present a method that is the result of experiences from a case study. It has enabled us to analyze models with much bigger state-spaces than what was possible without our method. The basic idea is to build partitions of the state-space of an analyzed system by iterative invocations of a model-checker. In each iteration the partitions are extended to represent a larger part of the state space, and if needed the partitions are further partitioned. Thereby the analysis problem is divided into a set of subproblems that can be analyzed independently of each other. We present how the method, implemented as a meta algorithm on-top of the Uppaal tool, has been applied in the case study.

  • 29.
    Lindström, Birgitta
    et al.
    University of Skövde, School of Humanities and Informatics. University of Skövde, The Informatics Research Centre.
    Pettersson, Paul
    Mälardalen University, Västeras, Sweden.
    Offutt, Jeff
    George Mason University, Fairfax, VA, United States.
    Generating Trace-Sets for Model-Based Testing2007In: Proceedings 18th IEEE International Symposiumon Software Reliability Engineering: ISSRE 2007 / [ed] Lisa O’Conner, IEEE, 2007, p. 171-180Conference paper (Refereed)
    Abstract [en]

    Model-checkers are powerful tools that can find individual traces through models to satisfy desired properties. These traces provide solutions to a number of problems. Instead of individual traces, software testing needs sets of traces that satisfy coverage criteria. Finding a trace set in a large model is difficult because model checkers generate single traces and use a lot of memory. Space and time requirements of modelchecking algorithms grow exponentially with respect to the number of variables and parallel automata of the model being analyzed. We present a method that generates a set of traces by iteratively invoking a model checker. The method mitigates the memory consumption problem by dynamically building partitions along the traces. This method was applied to a testability case study, and it generated the complete trace set, while ordinary model-checking could only generate 26%.

  • 30.
    Lisper, Björn
    et al.
    Mälardalen University, Sweden.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Potena, Pasqualina
    SICS Swedish ICT Västerås AB, Sweden.
    Saadatmand, Mehrdad
    SICS Swedish ICT Västerås AB, Sweden.
    Bohlin, Markus
    SICS Swedish ICT Västerås AB, Sweden.
    Targeted Mutation: Efficient Mutation Analysis for Testing Non-Functional Properties2017In: Proceedings: 10th IEEE International Conference on Software Testing, Verification and Validation: Workshops: ICSTW 2017, IEEE Computer Society, 2017, p. 65-68Conference paper (Refereed)
  • 31.
    Márki, András
    et al.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Mutation tools for Java2017In: SAC '17 Proceedings of the Symposium on Applied Computing, Association for Computing Machinery (ACM), 2017, p. 1364-1371Conference paper (Refereed)
  • 32.
    Offutt, Jeff
    et al.
    Software Engineering, George Mason University, Fairfax, USA.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Baral, Kesina
    Software Engineering, George Mason University, Fairfax, USA.
    Teaching an International Distributed Discussion-Based Course2019In: Proceedings of the 2019 International Conference on Frontiers in Education: Computer Science & Computer Engineering (FECS'19) / [ed] Hamid R. Arabnia, Leonidas Deligiannidis, Fernando G. Tinetti, Quoc-Nam Tran, CSREA, Computer Science Research, Education, and Applications Press , 2019, p. 149-154Conference paper (Refereed)
    Abstract [en]

    Small discussion-based courses pose several challenges. Low enrollments make the course difficult to justify and can restrict active discussions. Impromptu discussions are hard to encourage. Students come to class tired, not well prepared, reluctant to speak out, or not able to verbalize abstract thoughts fast enough to fully engage. Sometimes a few students dominate the discussions while other students stay silent. This paper describes a novel teaching model that was created to allow one professor to teach the same course at multiple universities. As the course design emerged, the asynchronous online distributed nature of the course turned out to not only solve the initial problem, but also other challenges of discussion-based courses. Instructors and students found this model led to more engagement, increased learning, and higher performance.

  • 33.
    Saadatmand, Mehrdad
    et al.
    RISE Research Institutes of Sweden, RISE SICS Västerås.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Aichernig, Bernhard K.
    Graz University of Technology, Institute for Software Technology, Austria.
    Special issue on testing extra-functional properties2020In: Software testing, verification & reliability, ISSN 0960-0833, E-ISSN 1099-1689, Vol. 30, no 1, article id e1726Article in journal (Other academic)
  • 34.
    Shah, Syed Muhammad Ali
    et al.
    Swedish Institute of Computer Science.
    Sundmark, Daniel
    Swedish Institute of Computer Science / Mälardalen University, Sw eden.
    Lindström, Birgitta
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Andler, Sten F.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Robustness Testing of Embedded Software Systems: An Industrial Interview Study2016In: IEEE Access, E-ISSN 2169-3536, Vol. 4, p. 1859-1871, article id 7438745Article in journal (Refereed)
    Abstract [en]

    Embedded software is at the core of current and future telecommunication, automotive, multimedia, and industrial automation systems. The success of practically any industrial application depends on the embedded software system’s dependability, and one method to verify the dependability of a system is testing its robustness. The motivation behind this study is to provide a knowledge base of the state of the practice in robustness testing of embedded software systems and to compare this to the state of the art. We have gathered information on the state of the practice in robustness testing from seven different industrial domains (telecommunication, automotive, multimedia, critical infrastructure, aerospace, consumer products, and banking) by conducting thirteen semi-structured interviews. We investigate different aspects of robustness testing, such as the general view of robustness, relation to requirements engineering and design, test execution, failures, and tools. We highlight knowledge from the state of the practice of robustness testing of embedded software systems. We found different robustness testing practices that have not been previously described. Our study shows that the state of the practice, when it comes to robustness testing, differs between organizations and is quite different from the state of the art described in the scientific literature. For example, methods commonly described in the literature (e.g., the fuzzy approach) are not used in the organizations we studied. Instead, the interviewees described several ad-hoc approaches that take specific scenarios into account (e.g., power failure or overload). Other differences we found concern classification of robustness failures, the hypothesized root causes of robustness failures, and the types of tools used for robustness testing. The study is a first step in capturing the state of the practice of robustness testing of embedded software systems. The results can be used by both researchers and- practitioners. Researchers can use our findings to understand the gap between the state of the art and the state of the practice and develop their studies to fill this gap. Practitioners can also learn from this knowledge base regarding how they can improve their practice and acquire other practices.

1 - 34 of 34
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