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  • 51.
    An, Jie
    et al.
    Tongji Univ, Sch Software Engn, Shanghai, Peoples R China.
    Zhan, Naijun
    Chinese Acad Sci, Inst Software, State Key Lab Comp Sci, Beijing, Peoples R China;Uni CAS, Beijing, Peoples R China.
    Li, Xiaoshan
    Univ Macau, Fac Sci & Technol, Macau, Peoples R China.
    Zhang, Miaomiao
    Tongji Univ, Sch Software Engn, Shanghai, Peoples R China.
    Wang, Yi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Uppsala Univ, Dept Informat Technol, Uppsala, Sweden.
    Model Checking Bounded Continuous-time Extended Linear Duration Invariants2018In: HSCC 2018: Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (HSCC), ASSOC COMPUTING MACHINERY , 2018, p. 81-90Conference paper (Refereed)
    Abstract [en]

    Extended Linear Duration Invariants (ELDI), an important subset of Duration Calculus, extends well-studied Linear Duration Invariants with logical connectives and the chop modality. It is known that the model checking problem of ELDI is undecidable with both the standard continuous-time and discrete-time semantics [12, 13], but it turns out to be decidable if only bounded execution fragments of timed automata are concerned in the context of the discrete-time semantics [36]. In this paper, we prove that this problem is still decidable in the continuous-time semantics, although it is well-known that model-checking Duration Calculus with the continuous-time semantics is much more complicated than the one with the discrete-time semantics. This is achieved by reduction to the validity of Quantified Linear Real Arithmetic (QLRA). Some examples are provided to illustrate the efficiency of our approach.

  • 52.
    Araujo, Hugo
    et al.
    Univ Fed Pernambuco, Recife, PE, Brazil.
    Carvalho, Gustavo
    Univ Fed Pernambuco, Recife, PE, Brazil.
    Mohaqeqi, Morteza
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Mousavi, Mohammad Reza
    Halmstad Univ, Halmstad, Sweden;Univ Leicester, Leicester, Leics, England.
    Sampaio, Augusto
    Univ Fed Pernambuco, Recife, PE, Brazil.
    Sound conformance testing for cyber-physical systems: Theory and implementation2018In: Science of Computer Programming, ISSN 0167-6423, E-ISSN 1872-7964, Vol. 162, p. 35-54Article in journal (Refereed)
    Abstract [en]

    Conformance testing is a formal and structured approach to verifying system correctness. We propose a conformance testing algorithm for cyber-physical systems, based on the notion of hybrid conformance by Abbas and Fainekos. We show how the dynamics of system specification and the sampling rate play an essential role in making sound verdicts. We specify and prove error bounds that lead to sound test-suites for a given specification and a given sampling rate. We use reachability analysis to find such bounds and implement the proposed approach using the CORA toolbox in Matlab. We apply the implemented approach on a case study from the automotive domain.

  • 53.
    Aronis, Stavros
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Lång, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Sagonas, Konstantinos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Optimal dynamic partial order reduction with observers2018In: Tools and Algorithms for the Construction and Analysis of Systems: Part II, Springer, 2018, Vol. 10806, p. 229-248Conference paper (Refereed)
    Abstract [en]

    Dynamic partial order reduction (DPOR) algorithms are used in stateless model checking (SMC) to combat the combinatorial explosion in the number of schedulings that need to be explored to guarantee soundness. The most effective of them, the Optimal DPOR algorithm, is optimal in the sense that it explores only one scheduling per Mazurkiewicz trace. In this paper, we enhance DPOR with the notion of observability, which makes dependencies between operations conditional on the existence of future operations, called observers. Observers naturally lead to a lazy construction of dependencies. This requires significant changes in the core of POR algorithms (and Optimal DPOR in particular), but also makes the resulting algorithm, Optimal DPOR with Observers, super-optimal in the sense that it explores exponentially less schedulings than Mazurkiewicz traces in some cases. We argue that observers come naturally in many concurrency models, and demonstrate the performance benefits that Optimal DPOR with Observers achieves in both an SMC tool for shared memory concurrency and a tool for concurrency via message passing, using both synthetic and actual programs as benchmarks.

  • 54.
    Asan, Noor Badariah
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hassan, Emadeldeen
    Perez, Mauricio D.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Joseph, Laya
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Berggren, Martin
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Augustine, Robin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Fat-intrabody communication at 5.8 GHz including impacts of dynamics body movementsManuscript (preprint) (Other academic)
  • 55.
    Asan, Noor Badariah
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Univ Tekn Malaysia Melaka, Fac Elect & Comp Engn, Durian Tunggal 76100, Malaysia.
    Hassan, Emadeldeen
    Umea Univ, Dept Comp Sci, S-90187 Umea, Sweden;Menoufia Univ, Dept Elect & Elect Commun, Menoufia 32952, Egypt.
    Perez, Mauricio David
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Shah, Syaiful Redzwan Mohd
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Velander, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Blokhuis, Taco J.
    Maastricht Univ, Dept Surg, Med Ctr, NL-6229 HX Maastricht, Netherlands.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. ¨.
    Augustine, Robin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Assessment of Blood Vessel Effect on Fat-Intrabody Communication Using Numerical and Ex-Vivo Models at 2.45 GHZ2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 89886-89900Article in journal (Refereed)
    Abstract [en]

    The potential offered by the intra-body communication (IBC) over the past few years has resulted in a spike of interest for the topic, specifically for medical applications. Fat-IBC is subsequently a novel alternative technique that utilizes fat tissue as a communication channel. This work aimed to identify such transmission medium and its performance in varying blood-vessel systems at 2.45 GHz, particularly in the context of the IBC and medical applications. It incorporated three-dimensional (3D) electromagnetic simulations and laboratory investigations that implemented models of blood vessels of varying orientations, sizes, and positions. Such investigations were undertaken by using ex-vivo porcine tissues and three blood-vessel system configurations. These configurations represent extreme cases of real-life scenarios that sufficiently elucidated their principal influence on the transmission. The blood-vessel models consisted of ex-vivo muscle tissues and copper rods. The results showed that the blood vessels crossing the channel vertically contributed to 5.1 dB and 17.1 dB signal losses for muscle and copper rods, respectively, which is the worst-case scenario in the context of fat-channel with perturbance. In contrast, blood vessels aligned-longitudinally in the channel have less effect and yielded 4.5 dB and 4.2 dB signal losses for muscle and copper rods, respectively. Meanwhile, the blood vessels crossing the channel horizontally displayed 3.4 dB and 1.9 dB signal losses for muscle and copper rods, respectively, which were the smallest losses among the configurations. The laboratory investigations were in agreement with the simulations. Thus, this work substantiated the fat-IBC signal transmission variability in the context of varying blood vessel configurations.

  • 56.
    Asan, Noor Badariah
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Velander, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Redzwan, Syaiful
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Perez, Mauricio D.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Hassan, Emadeldeen
    Blokhuis, Taco J.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Augustine, Robin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Effect of thickness inhomogeneity in fat tissue on in-body microwave propagation2018Conference paper (Refereed)
  • 57.
    Ashcroft, Michael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Fisher, Ali
    Univ Vienna, VORTEX, Vienna, Austria.
    Kaati, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Omer, Enghin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Prucha, Nico
    Kings Coll London, ICSR, London, England.
    Detecting jihadist messages on twitter2015In: Proc. 5th European Intelligence and Security Informatics Conference, IEEE Computer Society, 2015, p. 161-164Conference paper (Refereed)
    Abstract [en]

    Jihadist groups such as ISIS are spreading online propaganda using various forms of social media such as Twitter and YouTube. One of the most common approaches to stop these groups is to suspend accounts that spread propaganda when they are discovered. This approach requires that human analysts manually read and analyze an enormous amount of information on social media. In this work we make a first attempt to automatically detect messages released by jihadist groups on Twitter. We use a machine learning approach that classifies a tweet as containing material that is supporting jihadists groups or not. Even tough our results are preliminary and more tests needs to be carried out we believe that results indicate that an automated approach to aid analysts in their work with detecting radical content on social media is a promising way forward. It should be noted that an automatic approach to detect radical content should only be used as a support tool for human analysts in their work.

  • 58.
    Ashcroft, Michael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Johansson, Fredrik
    Swedish Def Res Agcy FOI, Stockholm, Sweden..
    Kaati, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Swedish Def Res Agcy FOI, Stockholm, Sweden..
    Shrestha, Amendra
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Multi-domain alias matching using machine learning2016In: Proc. 3rd European Network Intelligence Conference, IEEE, 2016, p. 77-84Conference paper (Refereed)
    Abstract [en]

    We describe a methodology for linking aliases belonging to the same individual based on a user's writing style (stylometric features extracted from the user generated content) and her time patterns (time-based features extracted from the publishing times of the user generated content). While most previous research on social media identity linkage relies on matching usernames, our methodology can also be used for users who actively try to choose dissimilar usernames when creating their aliases. In our experiments on a discussion forum dataset and a Twitter dataset, we evaluate the performance of three different classifiers. We use the best classifier (AdaBoost) to evaluate how well it works on different datasets using different features. Experiments show that combining stylometric and time based features yield good results on our synthetic datasets and a small-scale evaluation on real-world blog data confirm these results, yielding a precision over 95%. The use of emotion-related and Twitter-related features yield no significant impact on the results.

  • 59.
    Ashcroft, Michael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Kaati, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. FOI, Stockholm, Sweden.
    Meyer, Maxime
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A step towards detecting online grooming: Identifying adults pretending to be children2015In: Proc. 5th European Intelligence and Security Informatics Conference, IEEE Computer Society, 2015, p. 98-104Conference paper (Refereed)
    Abstract [en]

    Online grooming is a major problem in todays society where more and more time is spent online. To become friends and establish a relationship with their young victims in online communities, groomers often pretend to be children. In this paper we describe an approach that can be used to detect if an adult is pretending to be a child in a chat room conversation. The approach involves a two step process wherein authors are first classified as being children or adults, and then each child is being examined and false children distinguished from genuine children. Our results show that even if it is hard to separate ordinary adults from children in chat logs it is possible to distinguish real children from adults pretending to be children with a high accuracy. In this paper we will discuss the accuracy of the methods proposed, as well as the features that were important in their success. We believe that this work is an important step towards automated analysis of chat room conversation to detect and possible attempts of grooming. Our approach where we use text analysis to distinguish adults who are pretending to be children from actual children could be used to inform children about the true age of the person that they are communicating. This would be a step towards making the Internet more secure for young children and eliminate grooming.

  • 60.
    Ashcroft, Michael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Kaati, Lisa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Meyer, Maxime
    Are You Really a Child?: A Machine Learning Approach To Protect Children from Online Grooming2015In: Proc. National Symposium on Technology and Methodology for Security and Crisis Management: TAMSEC 2015, 2015Conference paper (Refereed)
    Abstract [en]

    Online grooming and sexual abuse of children is a major threat towards the security of todays society where more and more time is spent online. To become friends and establish a relationship with their young victims in online communities, groomers often pretend to be children. In this work we describe an approach that can be used to detect if an adult is pretending to be a child in a chat room conversation. Our results show that even if it is hard to separate ordinary adults from children in chat logs it is possible to distinguish real children from adults pretending to be children with a high accuracy.

  • 61. Ashjaei, Mohammad
    et al.
    Clegg, Kester
    Corneo, Lorenzo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Hawkins, Richard
    Jaradat, Omar
    Gulisano, Vincenzo Massimiliano
    Nikolakopoulos, Yiannis
    Service Level Agreements for Safe and Configurable Production Environments2018In: 2018 IEEE 23rd International Conference on Emerging Technologies and Factory Automation (ETFA), IEEE, 2018, p. 1252-1255Conference paper (Refereed)
    Abstract [en]

    This paper focuses on Service Level Agreements (SLAs) for industrial applications that aim to port some of the control functionalities to the cloud. In such applications, industrial requirements should be reflected in SLAs. In this paper, we present an approach to integrate safety-related aspects of an industrial application to SLAs. We also present the approach in a use case. This is an initial attempt to enrich SLAs for industrial settings to consider safety aspects, which has not been investigated thoroughly before.

  • 62.
    Atig, Mohamed Faouzi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bensalem, SaddekBliudze, SimonMonsuez, Bruno
    Verification and Evaluation of Computer and Communication Systems2018Conference proceedings (editor) (Other academic)
  • 63.
    Atig, Mohamed Faouzi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bollig, Benedikt
    CNRS, LSV, Paris, France.;ENS Paris Saclay, Paris, France.
    Habermehl, Peter
    CNRS, IRIF, Paris, France.;Univ Paris Diderot, Paris, France..
    Emptiness of Ordered Multi-Pushdown Automata is 2ETIME-Complete2017In: International Journal of Foundations of Computer Science, ISSN 0129-0541, Vol. 28, no 8, p. 945-975Article in journal (Refereed)
    Abstract [en]

    We consider ordered multi-pushdown automata, a multi-stack extension of pushdown automata that comes with a constraint on stack operations: a pop can only be performed on the first non-empty stack (which implies that we assume a linear ordering on the collection of stacks). We show that the emptiness problem for multi-pushdown automata is 2ETIME-complete. Containment in 2ETIME is shown by translating an automaton into a grammar for which we can check if the generated language is empty. The lower bound is established by simulating the behavior of an alternating Turing machine working in exponential space. We also compare ordered multi-pushdown automata with the model of bounded-phase (visibly) multi-stack pushdown automata, which do not impose an ordering on stacks, but restrict the number of alternations of pop operations on different stacks.

  • 64.
    Atig, Mohamed Faouzi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bouajjani, Ahmed
    LIAFA, CNRS and University of Paris Diderot.
    Kumar, K. Narayan
    Chennai Mathematical Institute, Chennai, India.
    Saivasan, Prakash
    TU Braunschweig, Germany.
    Parity Games on Bounded Phase Multi-pushdown Systems2017In: Networked Systems: 5th International Conference, NETYS 2017, Marrakech, Morocco, May 17-19, 2017, Proceedings / [ed] Amr El Abbadi and Benoit Garbinato, Cham, 2017, Vol. 10299, p. 272-287Conference paper (Refereed)
    Abstract [en]

    In this paper we address the problem of solving parity games over the configuration graphs of bounded phase multi-pushdown systems. A non-elementary decision procedure was proposed for this problem by A. Seth. In this paper, we provide a simple and inductive construction to solve this problem. We also prove a non-elementary lower-bound, answering a question posed by A. Seth.

  • 65.
    Atig, Mohamed Faouzi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bouajjani, Ahmed
    LIAFA, CNRS and University of Paris Diderot.
    Kumar, K. Narayan
    Chennai Mathematical Institute, Chennai, India.
    Saivasan, Prakash
    TU Braunschweig, Germany.
    Verification of Asynchronous Programs with Nested Locks2017In: 37th IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science, FSTTCS 2017, December 11-15, 2017, Kanpur, India / [ed] Satya Lokam and R. Ramanujam, Dagstuhl, Germany, 2017, Vol. 93, p. 11:1-11:14Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider asynchronous programs consisting of multiple recursive threads running in parallel. Each of the threads is equipped with a multi-set. The threads can create tasks and post them onto the multi-sets or read a task from their own. In addition, they can synchronise through a finite set of locks. In this paper, we show that the reachability problem for such class of asynchronous programs is undecidable even under the nested locking policy. We then show that the reachability problem becomes decidable (Exp-space-complete) when the locks are not allowed to be held across tasks. Finally, we show that the problem is NP-complete when in addition to previous restrictions, threads always read tasks from the same state.

  • 66.
    Atig, Mohamed Faouzi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bouajjani, Ahmed
    Narayan Kumar, K.
    Saivasan, Prakash
    Verifying quantitative temporal properties of procedural programs2018In: 29th International Conference on Concurrency Theory, Dagstuhl, Germany: Leibniz-Zentrum für Informatik , 2018, p. 15:1-17Conference paper (Refereed)
  • 67.
    Atig, Mohamed Faouzi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Chistikov, Dmitry
    Max Planck Inst Software Syst MPI SWS, Kaiserslautern, Germany..
    Hofman, Piotr
    Univ Paris Saclay, CNRS, LSV, St Aubin, France.;Univ Paris Saclay, ENS Cachan, St Aubin, France..
    Kumar, K. Narayan
    Chennai Math Inst, Madras, Tamil Nadu, India..
    Saivasan, Prakash
    Chennai Math Inst, Madras, Tamil Nadu, India.;Univ Kaiserslautern, Kaiserslautern, Germany..
    Zetzsche, Georg
    Univ Paris Saclay, CNRS, LSV, St Aubin, France.;Univ Paris Saclay, ENS Cachan, St Aubin, France..
    The complexity of regular abstractions of one-counter languages2016In: Proceedings Of The 31St Annual ACM-IEEE Symposium On Logic In Computer Science (LICS 2016), 2016, p. 207-216Conference paper (Refereed)
    Abstract [en]

    We study the computational and descriptional complexity of the following transformation: Given a one-counter automaton (OCA) A, construct a nondeterministic finite automaton (NFA) B that recognizes an abstraction of the language L (A) : its (1) downward closure, (2) upward closure, or (3) Parikh image. For the Parikh image over a fixed alphabet and for the upward and downward closures, we find polynomial-time algorithms that compute such an NFA. For the Parikh image with the alphabet as part of the input, we find a quasi-polynomial time algorithm and prove a completeness result: we construct a sequence of OCA that admits a polynomial-time algorithm iff there is one for all OCA. For all three abstractions, it was previously unknown whether appropriate NFA of sub-exponential size exist.

  • 68.
    Atig, Mohamed Faouzi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kumar, K. Narayan
    Saivasan, Prakash
    Acceleration in Multi-PushDown Systems2016In: Tools and Algorithms for the Construction and Analysis of Systems, Springer, 2016, p. 698-714Conference paper (Refereed)
  • 69.
    Atig, Mohamed Faouzi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Meyer, Roland
    TU Braunschweig, Germany.
    Muskalla, Sebastian
    TU Braunschweig, Germany.
    Saivasan, Prakash
    TU Braunschweig, Germany.
    On the Upward/Downward Closures of Petri Nets∗2017In: 42nd International Symposium on Mathematical Foundations of Computer Science (MFCS 2017) / [ed] Kim G. Larsen and Hans L. Bodlaender and Jean-Francois Raskin, Dagstuhl, Germany, 2017, Vol. 83, p. 49:1-49:14Conference paper (Refereed)
    Abstract [en]

    We study the size and the complexity of computing finite state automata (FSA) representing and approximating the downward and the upward closure of Petri net languages with coverability as the acceptance condition. We show how to construct an FSA recognizing the upward closure of a Petri net language in doubly-exponential time, and therefore the size is at most doubly exponential. For downward closures, we prove that the size of the minimal automata can be non-primitive recursive. In the case of BPP nets, a well-known subclass of Petri nets, we show that an FSA accepting the downward/upward closure can be constructed in exponential time. Furthermore, we consider the problem of checking whether a simple regular language is included in the downward/upward closure of a Petri net/BPP net language. We show that this problem is EXPSPACE-complete (resp. NP-complete) in the case of Petri nets (resp. BPP nets). Finally, we show that it is decidable whether a Petri net language is upward/downward closed.

  • 70.
    Aziz Abdulla, Parosh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Aiswarya, C.
    Chennai Mathematical Institute .
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Data Multi-Pushdown Automata2017In: The 28th International Conference on Concurrency Theory, CONCUR 2017, September 5-8, 2017, Berlin, Germany / [ed] Roland Meyer and Uwe Nestmann, Dagstuhl, Germany, 2017, Vol. 85, p. 38:1-38:17Conference paper (Refereed)
    Abstract [en]

    We extend the classical model of multi-pushdown systems by considering systems that operate on a finite set of variables ranging over natural numbers. The conditions on variables are defined via gap-order constraints that allow to compare variables for equality, or to check that the gap between the values of two variables exceeds a given natural number. Furthermore, each message inside a stack is equipped with a data item representing its value. When a message is pushed to the stack, its value may be defined by a variable. When a message is popped, its value may be copied to a variable. Thus, we obtain a system that is infinite in multiple dimensions, namely we have a number of stacks that may contain an unbounded number of messages each of which is equipped with a natural number. It is well-known that the verification of any non-trivial property of multi-pushdown systems is undecidable, even for two stacks and for a finite data-domain. In this paper, we show the decidability of the reachability problem for the classes of data multi-pushdown system that admit a bounded split-width (or equivalently a bounded tree-width). As an immediate consequence, we obtain decidability for several subclasses of data multi-pushdown systems. These include systems with single stacks, restricted ordering policies on stack operations, bounded scope, bounded phase, and bounded context switches.

  • 71.
    Backeman, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    New techniques for handling quantifiers in Boolean and first-order logic2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The automation of reasoning has been an aim of research for a long time. Already in 17th century, the famous mathematician Leibniz invented a mechanical calculator capable of performing all four basic arithmetic operators. Although automatic reasoning can be done in different fields, many of the procedures for automated reasoning handles formulas of first-order logic. Examples of use cases includes hardware verification, program analysis and knowledge representation.

    One of the fundamental challenges in first-order logic is handling quantifiers and the equality predicate. On the one hand, SMT-solvers (Satisfiability Modulo Theories) are quite efficient at dealing with theory reasoning, on the other hand they have limited support for complete and efficient reasoning with quantifiers. Sequent, tableau and resolution calculi are methods which are used to construct proofs for first-order formulas and can use more efficient techniques to handle quantifiers. Unfortunately, in contrast to SMT, handling theories is more difficult.

    In this thesis we investigate methods to handle quantifiers by restricting search spaces to finite domains which can be explored in a systematic manner. We present this approach in two different contexts.

    First we introduce a function synthesis based on template-based quantifier elimination, which is applied to gene interaction computation. The function synthesis is shown to be capable of generating smaller representations of solutions than previous solvers, and by restricting the constructed functions to certain forms we can produce formulas which can more easily be interpreted by a biologist.

    Secondly we introduce the concept of Bounded Rigid E-Unification (BREU), a finite form of unification that can be used to define a complete and sound sequent calculus for first-order logic with equality. We show how to solve this bounded form of unification in an efficient manner, yielding a first-order theorem prover utilizing BREU that is competitive with other state-of-the-art tableau theorem provers.

    List of papers
    1. Theorem proving with bounded rigid E-unification
    Open this publication in new window or tab >>Theorem proving with bounded rigid E-unification
    2015 (English)In: Automated Deduction – CADE-25, Springer, 2015, p. 572-587Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Springer, 2015
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 ; 9195
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-268734 (URN)10.1007/978-3-319-21401-6_39 (DOI)000363947500039 ()978-3-319-21400-9 (ISBN)
    Conference
    25th International Conference on Automated Deduction; August 1–7, 2015, Berlin, Germany
    Funder
    Swedish Research Council, 2014-5484
    Available from: 2015-07-25 Created: 2015-12-09 Last updated: 2018-01-10Bibliographically approved
    2. Efficient algorithms for bounded rigid E-unification
    Open this publication in new window or tab >>Efficient algorithms for bounded rigid E-unification
    2015 (English)In: Automated Reasoning with Analytic Tableaux and Related Methods, Springer, 2015, p. 70-85Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Springer, 2015
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 ; 9323
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-268735 (URN)10.1007/978-3-319-24312-2_6 (DOI)000366125200009 ()978-3-319-24311-5 (ISBN)
    Conference
    TABLEAUX 2015, September 21–24, Wroclaw, Poland
    Funder
    Swedish Research Council, 2014-5484
    Available from: 2015-11-08 Created: 2015-12-09 Last updated: 2018-01-10Bibliographically approved
    3. Algebraic polynomial-based synthesis for abstract Boolean network analysis
    Open this publication in new window or tab >>Algebraic polynomial-based synthesis for abstract Boolean network analysis
    2016 (English)In: Satisfiability Modulo Theories: SMT 2016, RWTH Aachen University , 2016, p. 41-50Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    RWTH Aachen University, 2016
    Series
    CEUR Workshop Proceedings, ISSN 1613-0073 ; 1617
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-311587 (URN)
    Conference
    14th International Workshop on Satisfiability Modulo Theories
    Available from: 2016-07-02 Created: 2016-12-29 Last updated: 2018-01-13Bibliographically approved
  • 72.
    Backeman, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Dunn, Sara-Jane
    Yordanov, Boyan
    Wintersteiger, Christoph M.
    Algebraic polynomial-based synthesis for abstract Boolean network analysis2016In: Satisfiability Modulo Theories: SMT 2016, RWTH Aachen University , 2016, p. 41-50Conference paper (Refereed)
  • 73.
    Backeman, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Efficient algorithms for bounded rigid E-unification2015In: Automated Reasoning with Analytic Tableaux and Related Methods, Springer, 2015, p. 70-85Conference paper (Refereed)
  • 74.
    Backeman, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Free variables and theories: Revisiting rigid E-unification2015In: Frontiers of Combining Systems, Springer, 2015, p. 3-13Conference paper (Refereed)
  • 75.
    Backeman, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Theorem proving with bounded rigid E-unification2015In: Automated Deduction – CADE-25, Springer, 2015, p. 572-587Conference paper (Refereed)
  • 76.
    Backeman, Peter
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Zeljic, Aleksandar
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bit-Vector Interpolation and Quantifier Elimination by Lazy Reduction2018In: Formal Methods in Computer-Aided Design / [ed] Nikolaj Bjørner, Arie Gurfinkel, 2018, p. 50-59Conference paper (Refereed)
    Abstract [en]

    The inference of program invariants over machine arithmetic, commonly called bit-vector arithmetic, is an important problem in verification. Techniques that have been successful for unbounded arithmetic, in particular Craig interpolation, have turned out to be difficult to generalise to machine arithmetic: existing bit-vector interpolation approaches are based either on eager translation from bit-vectors to unbounded arithmetic, resulting in complicated constraints that are hard to solve and interpolate, or on bit-blasting to propositional logic, in the process losing all arithmetic structure. We present a new approach to bitvector interpolation, as well as bit-vector quantifier elimination (QE), that works by lazy translation of bit-vector constraints to unbounded arithmetic. Laziness enables us to fully utilise the information available during proof search (implied by decisions and propagation) in the encoding, and this way produce constraints that can be handled relatively easily by existing interpolation and QE procedures for Presburger arithmetic. The lazy encoding is complemented with a set of native proof rules for bit-vector equations and non-linear (polynomial) constraints, this way minimising the number of cases a solver has to consider

  • 77.
    Ballew, William
    et al.
    School of Computing Science and Digital, Media Robert Gordon University, Aberdeen, United Kingdom.
    McDermott, Roger
    School of Computing Science and Digital, Media Robert Gordon University, Aberdeen, United Kingdom.
    Zarb, Mark
    School of Computing Science and Digital, Media Robert Gordon University, Aberdeen, United Kingdom.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Clear, Tony
    School of Computing and Mathematical Sciences, AUT University, Auckland, New Zealand.
    Investigations into the Use of Learning Agreements to Enhance Stakeholder Engagement and Promote Self-Efficacy in Computing Education2018In: 2018 IEEE Frontiers in Education Conference (FIE), Piscataway, NJ: IEEE, 2018Conference paper (Refereed)
    Abstract [en]

    We examine controversial issues surrounding the locus of control in the implementation of learning agreements, plans or contracts, in the context of the U.K. university-level Graduate Apprenticeship scheme. We begin by giving an account of the stakeholders and their positions as well as their motivating principles as they strive to maintain their respective loci of control with regard to the negotiation of the learning agreement.  We then describe the idiomatic challenges to implementation of a learning agreement and subsequent plan in work-based learning environments with a range of employers from different sectors. An investigation into the manner in which learning agreement tenets are changed due to competing pressures on the various stakeholders leads to a discussion of challenges to successful prioritisation of the learning plan that occur as a result of mutually exclusive requirement sets. We discuss the challenges that may present themselves in which the requirements of one set of stakeholders appear to conflict with others and the questions that are raised as those involved seek to ensure suitable standards of academic quality in difficult cases. Finally, we discuss whether learning agreements are the most appropriate operational instruments for maintaining standards in these circumstances.

  • 78.
    Bauer, Pavol
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Lindén, Jonatan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Engblom, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Efficient inter-process synchronization for parallel discrete event simulation on multicores2015In: Proc. 3rd ACM SIGSIM Conference on Principles of Advanced Discrete Simulation, New York: ACM Press, 2015, p. 183-194Conference paper (Refereed)
  • 79.
    Beecham, Sarah
    et al.
    Lero, Limerick, Ireland..
    Clear, Tony
    Auckland Univ Technol, Sch Engn Comp & Math Sci, Auckland, New Zealand..
    Barr, John
    Ithaca Coll, Dept Comp Sci, Ithaca, NY USA..
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Oudshoorn, Michael
    Northwest Missouri State Univ, Sch Comp Sci & Informat Syst, Maryville, MO USA..
    Noll, John
    Univ East London, London, England..
    Preparing tomorrow's software engineers for work in a global environment2017In: IEEE Software, ISSN 0740-7459, E-ISSN 1937-4194, Vol. 34, no 1, p. 9-12Article in journal (Refereed)
  • 80.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Eckerdal, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Learning practice and theory in programming education: Students’ lived experience2015In: Proc. 3rd International Conference on Learning and Teaching in Computing and Engineering, Los Alamitos, CA: IEEE Computer Society, 2015, p. 180-186Conference paper (Refereed)
  • 81.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Eckerdal, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computational Science.
    Learning to program: A discussion on the interplay of theory and practice2015In: Proc. 1st Al Baha University and Uppsala University Symposium on Quality in Computing Education, 2015, p. 16-18Conference paper (Refereed)
  • 82.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Pears, Arnold
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Nylén, Aletta
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Ahmad, Farooq
    Al Baha University, Al Baha, Saudi Arabia.
    Alghamdi, Bader
    Al Baha University, Al Baha, Saudi Arabia.
    Alghamdi, Khalid
    Al Baha University, Al Baha, Saudi Arabia.
    Alhabish, Ahmed
    Al Baha University, Al Baha, Saudi Arabia.
    Aljoufi, Abdullah
    Al Baha University, Al Baha, Saudi Arabia.
    Alzahrani, Eidah
    Al Baha University, Al Baha, Saudi Arabia.
    Alzahrani, Rami
    Al Baha University, Al Baha, Saudi Arabia.
    Aldmour, Ismat
    Al Baha University, Al Baha, Saudi Arabia.
    Athama, Areej
    Al Baha University, Al Baha, Saudi Arabia.
    AlSadoon, Hamada Shihad
    Al Baha University, Al Baha, Saudi Arabia.
    Budiarto, Rahmat
    Al Baha University, Al Baha, Saudi Arabia.
    Hafeez, Abdul
    Al Baha University, Al Baha, Saudi Arabia.
    Daupota, Nadeem Hassan
    Al Baha University, Al Baha, Saudi Arabia.
    Faiz, Dhafer
    Al Baha University, Al Baha, Saudi Arabia.
    Gabralla, Lubna Abdel Kareim
    Al Baha University, Al Baha, Saudi Arabia.
    Gamar, Mohammad
    Al Baha University, Al Baha, Saudi Arabia.
    Hannan, Abdul
    Al Baha University, Al Baha, Saudi Arabia.
    Kerim, Bedine
    Al Baha University, Al Baha, Saudi Arabia.
    Mazarbhuiya, F. A.
    Al Baha University, Al Baha, Saudi Arabia.
    Rabea, Ahmed
    Al Baha University, Al Baha, Saudi Arabia.
    Saleem, Muhammad Qaiser
    Al Baha University, Al Baha, Saudi Arabia.
    Saleh, Nimir
    Al Baha University, Al Baha, Saudi Arabia.
    Shenify, Mohamed
    Al Baha University, Al Baha, Saudi Arabia.
    Teaching and Learning Computer Science at Al Baha University, Saudi Arabia: Insights from a staff development course2015In: Proc. 3rd International Conference on Learning and Teaching in Computing and Engineering, Los Alamitos, CA: IEEE Computer Society, 2015, p. 1-6Conference paper (Refereed)
    Abstract [en]

    In this special session we meet a set of projects in computer science and engineering education at a university in Saudi Arabia. They are the product of a pedagogical development course ran in collaboration with a Swedish university during the academic year 2013/2014. The projects reflect the local situation, with its possibilities and challenges, and suggest steps to take, in the local environment, to enhance education. As such it is a unique document that brings insights from computer science and engineering education into the international literature.

  • 83.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Thota, Neena
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Learning from the experiences of international students2015In: Conference for University Pedagogical Development, Uppsala, Sweden: Uppsala University, 2015Conference paper (Other academic)
  • 84. Bi, Yin
    et al.
    Lv, Mingsong
    Song, Chen
    Xu, Wenyao
    Guan, Nan
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    AutoDietary: A wearable acoustic sensor system for food intake recognition in daily life2016In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 16, no 3, p. 806-816Article in journal (Refereed)
  • 85. Bi, Yin
    et al.
    Lv, Mingsong
    Wei, Yangjie
    Guan, Nan
    Yi, Wang
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Multi-feature fusion for thermal face recognition2016In: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 77, p. 366-374Article in journal (Refereed)
  • 86.
    Blom, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Model-Based Protocol Testing in an Erlang Environment2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Testing is the dominant technique for quality assurance of software systems. It typically consumes considerable resources in development projects, and is often performed in an ad hoc manner. This thesis is concerned with model-based testing, which is an approach to make testing more systematic and more automated. The general idea in model-based testing is to start from a formal model, which captures the intended behavior of the software system to be tested. On the basis of this model, test cases can be generated in a systematic way. Since the model is formal, the generation of test suites can be automated and with adequate tool support one can automatically quantify to which degree they exercise the tested software.

    Despite the significant improvements on model-based testing in the last 20 years, acceptance by industry has so far been limited. A number of commercially available tools exist, but still most testing in industry relies on manually constructed test cases.

    This thesis address this problem by presenting a methodology and associated tool support, which is intended to be used for model-based testing of communication protocol implementations in industry. A major goal was to make the developed tool suitable for industrial usage, implying that we had to consider several problems that typically are not addressed by the literature on model-based testing. The thesis presents several technical contributions to the area of model-based testing, including

    - a new specification language based on the functional programming language Erlang,

    - a novel technique for specifying coverage criteria for test suite generation, and

    - a technique for automatically generating test suites.

    Based on these developments, we have implemented a complete tool chain that generates and executes complete test suites, given a model in our specification language. The thesis also presents a substantial industrial case study, where our technical contributions and the implemented tool chain are evaluated. Findings from the case study include that test suites generated using (model) coverage criteria have at least as good fault-detection capability as equally large random test suites, and that model-based testing could discover faults in previously well-tested software where previous testing had employed a relaxed validation of requirements.

  • 87.
    Blom, Johan
    et al.
    Blossom Grove AB, Jarfalla, Sweden.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Nyström, Sven-Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Industrial Evaluation of Test Suite Generation Strategies for Model-Based Testing2016Conference paper (Refereed)
    Abstract [en]

    We report on a case study on model based testing for a commercially available telecom software system. A main purpose is to investigate how different strategies for test suite generation affect quality attributes of the generated test suites, in a realistic industrial environment. We develop a functional model in the form of an extended finite state machine, from which we generate test suites using several different (model) coverage criteria, alongside with randomly and manually generated test suites. We compare test suites with respect to fault-detection capability, incurred (source) code coverage, and test generation and execution time. The system under test is a commercially released version, not seeded with any faults, implying that exposed faults are "real" faults that passed previous testing. We did not find clear difference between coverage-based and random test suites. Test suite generation and execution is performed using the tool ERLY MARSH, developed by the first author.

  • 88.
    Borgh, Joakim
    et al.
    Ericsson Res, Stockholm, Sweden.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ohlman, Börje
    Ericsson Res, Stockholm, Sweden.
    Malik, Adeel Mohammad
    Ericsson Res, Stockholm, Sweden.
    Employing attribute-based encryption in systems with resource constrained devices in an information-centric networking context2017In: 2017 Global Internet of Things Summit (GIoTS), IEEE, 2017, p. 397-402Conference paper (Other academic)
    Abstract [en]

    Attribute-Based Encryption (ABE) is considered to be one of the most promising ways to be enforce access control in Information-Centric Networking (ICN). As the Internet of Things (IoT) is being considered as one of the primary use cases for ICN it raises the question of the compatibility between IoT and ABE. An important part of the IoT is the resource constrained devices, for them there is a challenge to perform the computationally expensive operations required for ABE. In this paper we consider ABE in sensor networks and discuss the strengths and weaknesses of a system solution where the ABE operations are performed on the sensors. To properly discuss these concerns we have implemented two ABE schemes, a Single-authority ABE (SA-CP-ABE) scheme and a Multi-authority ABE (MA-CP-ABE) scheme. Results regarding the execution time, RAM usage, data overhead and battery consumption of these implementations on a sensor are presented. We conclude that it is possible, already today, to perform ABE on sensors for smaller policies. The main limitation in deploying ABE in sensors is the RAM size of the sensors.

  • 89.
    Brain, Martin
    et al.
    Univ Oxford, Dept Comp Sci, Oxford, England.
    Tinelli, Cesare
    Univ Iowa, Dept Comp Sci, Iowa City, IA 52242 USA.
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Wahl, Thomas
    Northeastern Univ, Coll Comp & Informat Sci, Boston, MA 02115 USA.
    An automatable formal semantics for IEEE-754 floating-point arithmetic2015In: Proc. 22nd Symposium on Computer Arithmetic / [ed] Muller, JM; Tisserand, A; Villalba, J, IEEE Computer Society, 2015, p. 160-167Conference paper (Refereed)
    Abstract [en]

    Automated reasoning tools often provide little or no support to reason accurately and efficiently about floating-point arithmetic. As a consequence, software verification systems that use these tools are unable to reason reliably about programs containing floating-point calculations or may give unsound results. These deficiencies are in stark contrast to the increasing awareness that the improper use of floating-point arithmetic in programs can lead to unintuitive and harmful defects in software. To promote coordinated efforts towards building efficient and accurate floating-point reasoning engines, this paper presents a formalization of the IEEE-754 standard for floating-point arithmetic as a theory in many-sorted first-order logic. Benefits include a standardized syntax and unambiguous semantics, allowing tool interoperability and sharing of benchmarks, and providing a basis for automated, formal analysis of programs that process floating-point data.

  • 90.
    Cajander, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Golay, Diane
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Moll, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Nylén, Aletta
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Pears, Arnold
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Peters, Anne-Kathrin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    McDermott, Roger
    Unexpected student behaviour and learning opportunities: Using the theory of planned behaviour to analyse a critical incident2017In: Proc. 47th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2017Conference paper (Refereed)
  • 91.
    Cajander, Åsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Sandblad, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Lind, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    McDermott, Roger
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Vision seminars and administration of university education: A case study2015In: Proc. 1st Al Baha University and Uppsala University Symposium on Quality in Computing Education, 2015, p. 29-32Conference paper (Refereed)
  • 92.
    Carlos, Perez Penichet
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication. Uppsala Univ, Uppsala, Sweden.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. RISE SICS, Lulea, Sweden.
    Carrier Scheduling in IoT Networks with Interoperable Battery-free Backscatter Tags2019In: IPSN '19: Proceedings of the 2019 International Conference on Information Processing in Sensor Networks, Association for Computing Machinery (ACM), 2019, p. 329-330Conference paper (Refereed)
    Abstract [en]

    New battery-free backscatter tags that integrate with unmodified standard IoT devices can extend the latter's sensing capabilities in a scalable and cost effective way. Existing IoT nodes can provide the unmodulated carrier needed by the new nodes, avoiding the need for additional infrastructure. This, however, puts extra energetic demands on constrained IoT nodes while increasing interference and contention in the network. We use a slotted MAC protocol to guarantee synchronization between transmitters, receivers and carrier generators. We then express the slot allocation problem as a Constraint Optimization Problem (COP) that parallelizes interrogations to battery-free tags when they do not collide with each other and reuses carriers for multiple tags looking to minimize the total time and the number of carrier generators needed to interrogate a set of tags. In networks with sufficient battery-free nodes we obtain a 25% reduction in the number of necessary carriers and a 50% decrease in interrogation time in most cases; leading to significant energy savings, reduced collisions and improved latency.

  • 93. Cassel, Lillian
    et al.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Goldweber, Michael
    Sheard, Judy
    Four relections on the history of ITiCSE2018In: ACM inroads, ISSN 2153-2184, E-ISSN 2153-2192, Vol. 9, no 4, p. 40-46Article in journal (Refereed)
    Abstract [en]

    In 1996, recognizing a growing worldwide interest in community education, SIGCSE started a new conference in Europe—now known as the Innovation and Technology in Computer Science Education conference (ITiCSE). Following the success of the first ITiCSE, it has been held annually, typically in Europe, ever since. ITiCSE has developed its own special character, providing unique and valuable experiences for participants. In this article we reflect upon ITiCSE, its establishment and development into a leading venue for computing education researchers and practitioners.

  • 94.
    Cassel, Sofia
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Learning Component Behavior from Tests: Theory and Algorithms for Automata with Data2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Formal models are often used to describe the behavior of a computer program or component. Behavioral models have many different usages, e.g., in model-based techniques for software development and verification,such as model checking and model based testing.

    The application of model-based techniques is hampered by the current lack of adequate models for most actual systems, largely due to the significant manual effort typically needed to construct them. To remedy this, automata learning techniques (whereby models can be inferred by performing tests on a component) have been developed for finite automata that capture control flow. However, many usages requiremodels also to capture data flow, i.e., how behavior is affected by data values in method invocations and commands. Unfortunately, techniques are less developed for models that combinecontrol flow with data.

    In this thesis, we extend automata learning to infer automata models that captureboth control flow and data flow. We base our technique on a corresponding extension of classical automata theoryto capture data.

    We define a formalism for register automata, a model that extends finite automata by adding registers that can store data values and be used in guards and assignments on transitions. Our formalism is parameterized on a theory, i.e., a set of relations on a data domain. We present a Nerode congruence for the languages that our register automata can recognize, and provide a Myhill-Nerode theorem for constructing canonical register automata, thereby extending classical automata theory to register automata.

    We also present a learning algorithm for register automata: the new SL* algorithm, which extends the well-known L* algorithm for finite automata. The SL* algorithm is based on our new Nerode congruence, and uses a novel technique to infer symbolic data constraints on parameters. We evaluated our algorithm in a black-box scenario, inferring, e.g., the connection establishment phase of TCP and a priority queue, in addition to a number of smaller models. The SL* algorithm is implemented in a tool, which allows for use in more realistic settings, e.g., where models have both input and output, and for directly inferring Java classes.

    List of papers
    1. Inferring Canonical Register Automata
    Open this publication in new window or tab >>Inferring Canonical Register Automata
    2012 (English)In: Verification, Model Checking, and Abstract Interpretation - 13th International Conference, / [ed] Viktor Kuncak and Andrey Rybalchenko, Springer, 2012, p. 251-266Conference paper, Published paper (Refereed)
    Abstract [en]

    In this paper, we present an extension of active automata learning to register automata, an automaton model which is capable of expressing the influence of data on control flow. Register automata operate on an infinite data domain, whose values can be assigned to registers and compared for equality. Our active learning algorithm is unique in that it directly infers the effect of data values on control flow as part of the learning process. This effect is expressed by means of registers and guarded transitions in the resulting register automata models. The application of our algorithm to a small example indicates the impact of learning register automata models: Not only are the inferred models much more expressive than finite state machines, but the prototype implementation also drastically outperforms the classic L* algorithm, even when exploiting optimal data abstraction and symmetry reduction.

    Place, publisher, year, edition, pages
    Springer, 2012
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 ; 7148
    National Category
    Computer Sciences
    Research subject
    Computer Science
    Identifiers
    urn:nbn:se:uu:diva-189969 (URN)10.1007/978-3-642-27940-9 (DOI)978-3-642-27939-3 (ISBN)
    Conference
    VMCAI 2012, Philadelphia, PA, USA, January 22-24, 2012.
    Projects
    ConnectUPMARC
    Available from: 2013-01-05 Created: 2013-01-05 Last updated: 2018-01-11
    2. RALib: A LearnLib extension for inferring EFSMs
    Open this publication in new window or tab >>RALib: A LearnLib extension for inferring EFSMs
    2015 (English)Conference paper, Published paper (Refereed)
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-265365 (URN)
    Conference
    DIFTS
    Available from: 2015-10-28 Created: 2015-10-28 Last updated: 2018-01-10
    3. Active Learning for Extended Finite State Machines
    Open this publication in new window or tab >>Active Learning for Extended Finite State Machines
    2015 (English)Report (Other academic)
    Series
    Technical report / Department of Information Technology, Uppsala University, ISSN 1404-3203 ; 2015-032
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-265368 (URN)
    Available from: 2015-10-28 Created: 2015-10-28 Last updated: 2018-01-10
    4. A succinct canonical register automaton model
    Open this publication in new window or tab >>A succinct canonical register automaton model
    Show others...
    2015 (English)In: Journal of Logical and Algebraic Methods in Programming, ISSN 2352-2208, Vol. 84, no 1, p. 54-66Article in journal (Refereed) Published
    Keywords
    register automata, data languages, canonical model, Myhill–Nerode, automata theory
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-237501 (URN)10.1016/j.jlamp.2014.07.004 (DOI)000347601600005 ()
    Conference
    23rd Nordic Workshop on Programming Theory (NWPT 2011)
    Projects
    Connect
    Available from: 2014-08-04 Created: 2014-12-03 Last updated: 2018-01-11Bibliographically approved
  • 95.
    Cassel, Sofia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Falk, Howar
    IPSSE, TU Clausthal, Germany.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    RALib: A LearnLib extension for inferring EFSMs2015Conference paper (Refereed)
  • 96.
    Cassel, Sofia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Howar, Falk
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Merten, Maik
    Steffen, Bernhard
    A succinct canonical register automaton model2015In: Journal of Logical and Algebraic Methods in Programming, ISSN 2352-2208, Vol. 84, no 1, p. 54-66Article in journal (Refereed)
  • 97.
    Cassel, Sofia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Howar, Falk
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Steffen, Bernhard
    Active learning for extended finite state machines2016In: Formal Aspects of Computing, ISSN 0934-5043, E-ISSN 1433-299X, Vol. 28, no 2, p. 233-263Article in journal (Refereed)
  • 98.
    Cassel, Sofia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Howar, Falk
    IPSSE, TU Clausthal, Germany.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Steffen, Bernhard
    TU Dortmund, Germany.
    Active Learning for Extended Finite State Machines2015Report (Other academic)
  • 99.
    Cassel, Sofia
    et al.
    Scania CV AB, Sodertalje, Sweden.
    Howar, Falk
    Dortmund Univ Technol, Dortmund, Germany;Fraunhofer ISST, Dortmund, Germany.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Steffen, Bernhard
    TU Dortmund, Chair Programming Syst, Dortmund, Germany.
    Extending Automata Learning to Extended Finite State Machines2018In: Machine Learning for Dynamic Software Analysis: Potentials and Limits / [ed] Bennaceur, A Hahnle, R Meinke, K, Springer, 2018, p. 149-177Conference paper (Refereed)
    Abstract [en]

    Automata learning is an established class of techniques for inferring automata models by observing how they respond to a sample of input words. Recently, approaches have been presented that extend these techniques to infer extended finite state machines (EFSMs) by dynamic black-box analysis. EFSMs model both data flow and control behavior, and their mutual interaction. Different dialects of EFSMs are widely used in tools for model-based software development, verification, and testing. This survey paper presents general principles behind some of these recent extensions. The goal is to elucidate how the principles behind classic automata learning can be maintained and guide extensions to more general automata models, and to situate some extensions with respect to these principles.

  • 100.
    Cassel, Sofia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Victor, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    A structured approach to training open-ended problem solving2015In: Proc. 45th ASEE/IEEE Frontiers in Education Conference, Piscataway, NJ: IEEE Press, 2015, p. 417-420Conference paper (Refereed)
    Abstract [en]

    Students in engineering are well trained in solving specified problems, but some have trouble when given problems where there is more than one solution. In their professional life they are much more often confronted with open-ended problems, where there may be more than one solution, and where there may be many ways to reach each one. The goals may be vague, the problem may be underspecified, and the fresh graduate frustrated by the new situation.

    We present a structured approach to training students in open-ended problem solving. We have introduced a half-day workshop to help students learn to work with open-ended, ill-structured problems, using a different approach than they would for the well-structured problems they are used to.

    Our results indicate that students have become more creative. Compared to previous years, the students explore more paths towards the goal, and use more elaborate methods. Their approach is similar to that typically used by the best students in previous instances of the course. Students mention creativity and group dynamics as positive aspects of the workshop and the following lab.

    We conclude that with proper guidance and training, even weaker students can become more creative when solving open-ended problems.

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