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  • 101.
    Abdelrasoul, Nader
    Blekinge Institute of Technology, Faculty of Computing, Department of Computer Science and Engineering.
    Optimization Techniques For an Artificial Potential Fields Racing Car Controller2013Independent thesis Advanced level (degree of Master (Two Years))Student thesis
    Abstract [en]

    Context. Building autonomous racing car controllers is a growing field of computer science which has been receiving great attention lately. An approach named Artificial Potential Fields (APF) is used widely as a path finding and obstacle avoidance approach in robotics and vehicle motion controlling systems. The use of APF results in a collision free path, it can also be used to achieve other goals such as overtaking and maneuverability. Objectives. The aim of this thesis is to build an autonomous racing car controller that can achieve good performance in terms of speed, time, and damage level. To fulfill our aim we need to achieve optimality in the controller choices because racing requires the highest possible performance. Also, we need to build the controller using algorithms that does not result in high computational overhead. Methods. We used Particle Swarm Optimization (PSO) in combination with APF to achieve optimal car controlling. The Open Racing Car Simulator (TORCS) was used as a testbed for the proposed controller, we have conducted two experiments with different configuration each time to test the performance of our APF- PSO controller. Results. The obtained results showed that using the APF-PSO controller resulted in good performance compared to top performing controllers. Also, the results showed that the use of PSO proved to enhance the performance compared to using APF only. High performance has been proven in the solo driving and in racing competitions, with the exception of an increased level of damage, however, the level of damage was not very high and did not result in a controller shut down. Conclusions. Based on the obtained results we have concluded that the use of PSO with APF results in high performance while taking low computational cost.

  • 102.
    Abdiu, Daniel
    et al.
    Jönköping University, Jönköping International Business School.
    Strandberg, Mikael
    Jönköping University, Jönköping International Business School.
    Stridsberg, Martin
    Jönköping University, Jönköping International Business School.
    The impact of a real-time IT-Logistics solution: Implementation effects and consequences2005Independent thesis Advanced level (degree of Magister), 10 points / 15 hpStudent thesis
    Abstract [en]

    Today’s business market is highly competitive, therefore companies need to be constantly updated and change the way they operate their business, in order to survive and remain competitive. The situation on today’s market requires that companies have the ability to quickly respond to market changes and new customer demands within short product lifecycles. In order to deal with this new market situation, companies need to improve the integration with other companies within their business. This integration facilitates the companies’ ability to quickly adapt to new market situations and survive on a fast changing market. One of the main underlying concepts of this collaborative commerce is Supply Chain Management (SCM) which integrates and coordinates a company’s processes both internally and externally. Information Technology (IT) could improve the effectiveness of SCM. IT-solutions make the business processes more effective and improves the integration with other actors within the supply chain. The purpose with this thesis is to describe and explain the effects for businesses and the consequences for its processes when implementing a real-time IT-Logistics solution together with identifying the critical success factors. The thesis has been conducted by studying theory regarding supply chain management, business renewal and implementation effects. Further, a case study has been conducted where three actors have been interviewed; a manufacturer (Volvo Powertrain), a subcontractor (Metallfabriken Ljunghäll AB) and a system developer (PipeChain). The analysis of the theoretical framework and the empirical research has contributed with an identification of major effects and consequences when implementing a real-time IT-Logistics solution. Some of the effects are: inventory reduction, higher delivery accuracy, improved relations and increased flexibility. Examples of consequences these effects have caused are: more accurate planning and production, effective production processes as well as an improved delivery process. Additionally, success factors for an implementation have been identified such as mutual trust, understanding of change and evaluation.

  • 103.
    Abdlbari, Abdulbari
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies.
    Användning av mobilapplikationer i smartphones hos unga vuxna: En fallstudie bland studenter och arbetstagare2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Nu förtiden har det blivit allt vanligare att människor använder sig av smartphones. I denna uppsats har jag kartlagt smartphone-användares användningsvanor och mönster hos unga vuxna som antingen studerar eller arbetar. För att få fram den information jag behöver har jag valt att använda mig av dagböcker där sex stycken respondenter deltog under en fyra dagars period och även intervjuer där tre av de sex respondenterna var deltagande efter genomförandet av dagböckerna. Mina resultat visar fascinerande nog att smartphones används till största del på platser där användarna är relativt stillasittande som till exempel i hemmet. Dessutom har det visat sig att studenter har en stor användning av applikationer och där med smartphones, ofta i samband med deras studier, speciellt applikationer kopplade till molntjänster.

  • 104.
    Abdlbari, Abdulbari
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies.
    Parkeringsapplikationen: Utveckling av en mobilapplikation för iPhone.2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report describes procedures and preparations made for developing a mobile application.Using a questionnaire and usability tests, I have developed a design document for a parkingapplication for the iPhone 4. The purpose of the application is to help drivers find allowedparking spaces thus making roads safer for everyone while the driver avoids parking tickets.

  • 105.
    Abdlwafa, Alan
    et al.
    KTH, School of Computer Science and Communication (CSC).
    Edman, Henrik
    KTH, School of Computer Science and Communication (CSC).
    Distributed Graph Mining: A study of performance advantages in distributed data mining paradigms when processing graphs using PageRank on a single node cluster2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Distributed data mining is a relatively new area within computer science that is steadily growing, emerging from the demands of being able to gather and process various distributed data by utilising clusters. This report presents the properties of graph structured data and what paradigms to use for efficiently processing the data type, based on comprehensive theoretical studies applied on practical tests performed on a single node cluster. The results in the study showcase the various performance aspects of processing graph data, using different open source paradigm frameworks and amount of shards used on input. A conclusion to be drawn from this study is that there are no real performance advantages to using distributed data mining paradigms specifically developed for graph data on single machines. 

  • 106.
    Abdollahi, Kamran
    et al.
    Computer and Science Department Iran University of Science and Technology Tehran, Iran.
    Shams Shafigh, Alireza
    Computer and Science Department Iran University of Science and Technology Tehran, Iran.
    Kassler, Andreas
    Karlstad University, Faculty of Economic Sciences, Communication and IT, Department of Computer Science. Karlstad University, Faculty of Economic Sciences, Communication and IT, Centre for HumanIT.
    Improving Performance of On Demand Multicast Routing by deleting lost join query packet2010In: Proceedings of The Sixth Advanced International Conference on Telecommunications - AICT 2010, IEEE conference proceedings, 2010, p. 316-322Conference paper (Refereed)
    Abstract [en]

    A Mobile ad hoc network is a collection of wireless nodes that dynamically organize themselves to form a network without the need for any fixed infrastructure or centralized administration. The network topology dynamically changes frequently in an unpredictable manner since nodes are free to move. Support for multicasting is essential in such environment as it is considered to be an efficient way to deliver information from source nodes to many client nodes. A problem with multicast routing algorithms is their efficiency as their forwarding structure determines the overall network resource consumption makes them significantly less efficient than unicast routing algorithms. In this research, we improve the performance of the popular ODMRP multicast routing protocol by restricting the domain of join query packets, which have been lost. This is achieved by augmenting the join query packets with minimum extra information (one field), which denotes the number of the visited node from previous forwarding group. Simulation results show, that our mechanisms significantly reduce the control traffic and thus the overall latency and power consumption in the network.

  • 107.
    Abdolmajid Ahmad, Bookan
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Programmering av generativ konst i C# .Net2014Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete utfördes på IDA (Institutionen för datavetenskap) vid Linköpings universitet. 

    Syftet med det här examensarbetet var att utveckla ett program som skulle skapa förutsättningar för generativ konst med hjälp av MyPaint som är ett digitalt rit/målarverktyg. Metoden gick ut på att registrera vad användaren skapat för komponenter, dvs. musinteraktioner och kortkommandon, och därefter använda dem algoritmiskt.

    Examensarbetet resulterades i ett program (SharpArt), som fångar musinteraktioner samt simulerar tangentbordstryckningar (kortkommandon) från och till Mypaint, vilket i sin tur skapar komponenter som används algoritmiskt. Programmet kan även positionera objektet på canvasen enligt det önskade koordinatvärdet.

  • 108.
    Abdukalikova, Anara
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Machine Learning assisted system for the resource-constrained atrial fibrillation detection from short single-lead ECG signals2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An integration of ICT advances into a conventional healthcare system is spreading extensively nowadays. This trend is known as Electronic health or E-Health. E-Health solutions help to achieve the sustainability goal of increasing the expected lifetime while improving the quality of life by providing a constant healthcare monitoring. Cardiovascular diseases are one of the main killers yearly causing approximately 17.7 million deaths worldwide. The focus of this work is on studying the detection of one of the cardiovascular diseases – Atrial Fibrillation (AF) arrhythmia.  This type of arrhythmia has a severe influence on the heart health conditions and could cause congestive heart failure (CHF), stroke, and even increase the risk of death. Therefore, it is important to detect AF as early as possible. In this thesis we focused on studying various machine learning techniques for AF detection using only short single lead Electrocardiography recordings. A web-based solution was built as a final prototype, which first simulates the reception of a recorded signal, conducts the preprocessing, makes a prediction of the AF presence, and visualizes the result. For the AF detection the relatively high accuracy score was achieved comparable to the one of the state-of-the-art. The work was based on the investigation of the proposed architectures and the usage of the database of signals from the 2017 PhysioNet/CinC Challenge. However, an additional constraint was introduced to the original problem formulation, since the idea of a future deployment on the resource-limited devices places the restrictions on the complexity of the computations being performed for achieving the prediction. Therefore, this constraint was considered during the development phase of the project.

  • 109.
    Abdul Khaliq, Ali
    et al.
    Örebro University, School of Science and Technology.
    Pecora, Federico
    Örebro University, School of Science and Technology.
    Saffiotti, Alessandro
    Örebro University, School of Science and Technology.
    Point-to-point safe navigation of a mobile robot using stigmergy and RFID technology2016In: 2016 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 1497-1504, article id 7759243Conference paper (Refereed)
    Abstract [en]

    Reliable autonomous navigation is still a challenging problem for robots with simple and inexpensive hardware. A key difficulty is the need to maintain an internal map of the environment and an accurate estimate of the robot’s position in this map. Recently, a stigmergic approach has been proposed in which a navigation map is stored into the environment, on a grid of RFID tags, and robots use it to optimally reach predefined goal points without the need for internal maps. While effective,this approach is limited to a predefined set of goal points. In this paper, we extend this approach to enable robots to travel to any point on the RFID floor, even if it was not previously identified as a goal location, as well as to keep a safe distance from any given critical location. Our approach produces safe, repeatable and quasi-optimal trajectories without the use of internal maps, self localization, or path planning. We report experiments run in a real apartment equipped with an RFID floor, in which a service robot either reaches or avoids a user who wears slippers equipped with an RFID tag reader.

  • 110.
    Abdulahad, Bassam
    et al.
    Linköping University, Department of Computer and Information Science.
    Lounis, Georgios
    Linköping University, Department of Computer and Information Science.
    A user interface for the ontology merging tool SAMBO2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Ontologies have become an important tool for representing data in a structured manner. Merging ontologies allows for the creation of ontologies that later can be composed into larger ontologies as well as for recognizing patterns and similarities between ontologies. Ontologies are being used nowadays in many areas, including bioinformatics. In this thesis, we present a desktop version of SAMBO, a system for merging ontologies that are represented in the languages OWL and DAML+OIL. The system has been developed in the programming language JAVA with JDK (Java Development Kit) 1.4.2. The user can open a file locally or from the network and can merge ontologies using suggestions generated by the SAMBO algorithm. SAMBO provides a user-friendly graphical interface, which guides the user through the merging process.

  • 111.
    Abdulaziz Ali Haseeb, Mohamed
    KTH, School of Computer Science and Communication (CSC), Robotics, perception and learning, RPL.
    Passive gesture recognition on unmodified smartphones using Wi-Fi RSSI2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The smartphone is becoming a common device carried by hundreds of millions of individual humans worldwide, and is used to accomplish a multitude of different tasks like basic communication, internet browsing, online shopping and fitness tracking. Limited by its small size and tight energy storage, the human-smartphone interface is largely bound to the smartphones small screens and simple keypads. This prohibits introducing new rich ways of interaction with smartphones.

     

    The industry and research community are working extensively to find ways to enrich the human-smartphone interface by either seizing the existing smartphones resources like microphones, cameras and inertia sensors, or by introducing new specialized sensing capabilities into the smartphones like compact gesture sensing radar devices.

     

    The prevalence of Radio Frequency (RF) signals and their limited power needs, led us towards investigating using RF signals received by smartphones to recognize gestures and activities around smartphones. This thesis introduces a solution for recognizing touch-less dynamic hand gestures from the Wi-Fi Received Signal Strength (RSS) received by the smartphone using a recurrent neural network (RNN) based probabilistic model. Unlike other Wi-Fi based gesture recognition solutions, the one introduced in this thesis does not require a change to the smartphone hardware or operating system, and performs the hand gesture recognition without interfering with the normal operation of other smartphone applications.

     

    The developed hand gesture recognition solution achieved a mean accuracy of 78% detecting and classifying three hand gestures in an online setting involving different spatial and traffic scenarios between the smartphone and Wi-Fi access points (AP). Furthermore the characteristics of the developed solution were studied, and a set of improvements have been suggested for further future work.

  • 112.
    Abdulhomeed, Bashar
    Örebro University, Örebro University School of Business.
    Contemporary Research on e-democracy: A Literature Review2013Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
  • 113.
    Abdulla, Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Delzanno, Giorgio
    Henda, Ben
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rezine, Ahmed
    Monotonic Abstraction: on Efficient Verification of Parameterized Systems2009In: International Journal of Foundations of Computer Science, ISSN 0129-0541, Vol. 20, no 5, p. 779-801Article in journal (Refereed)
    Abstract [en]

    We introduce the simple and efficient method of monotonic abstraction to prove safety properties for parameterized systems with linear topologies. A process in the system is a finite-state automaton, where the transitions are guarded by both local and global conditions. Processes may communicate via broadcast, rendez-vous and shared variables over finite domains. The method of monotonic abstraction derives an over-approximation of the induced transition system that allows the use of a simple class of regular expressions as a symbolic representation. Compared to traditional regular model checking methods, the analysis does not require the manipulation of transducers, and hence its simplicity and efficiency. We have implemented a prototype that works well on several mutual exclusion algorithms and cache coherence protocols

  • 114.
    Abdulla, Muntazar
    KTH, School of Information and Communication Technology (ICT).
    Cu-tråd som elektrisk ledare i CIGS-tunnfilmssolceller för att sänka silvermängden utan att förlora verkningsgrad2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The solar industry is bigger than ever and continues to grow while competition between the solar cell manufacturers is increasing. This is something that has lowered the prices of solar cells and reduces the profitability for manufacturers. This thesis aims to lower the cost of production without losing efficiency by using copper wires as conductors in CIGS thin film solar cells. Silver paste is printed on the surface on the solar cell and represents 1/5 of the cell manufacturing costs. That is why this project focuses on how to lower the amount of silver in the solar cell without losing efficiency, this is a hands-on project. The work is done by improving the solar cell with implementation of own ideas and innovations. This is made by taking advantage of the benefits of copper wires and by changing the solar cell pattern. The results showed that one can reduce the amount of silver paste by up to 70% in each solar cell by producing a new silver print with much less silver. The silver-coated copper wires gave the highest results as conductors to lead out electricity from the surface because they can be made much thinner than today's solar cells conductors and obscure the surface less. This gave efficiencies of 10-11% which is in line with the production solar cells modules on Midsummer. The system has also been proved stable.

  • 115.
    Abdulla, PA
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology, Computer Systems. DEPARTMENT OF COMPUTER SYSTEMS.
    Boasson, L
    Bouajjani, A
    Effective Lossy Queue Languages.2001In: ICALP'2001, 28th Int. Colloquium on Automata, Languages and Programmming., 2001Conference paper (Refereed)
  • 116.
    Abdulla, PA
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. DEPARTMENT OF COMPUTER SYSTEMS.
    Jonsson, B
    Channel Abstractions in Protocol Verification2001In: CONCUR'2001, 12th Int. Conf. on Concurrency Theory, 2001Conference paper (Refereed)
  • 117.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Bouajjani, Ahmed
    Jonnson, Bengt
    Nilsson, Marcus
    Handling Global Conditions in Parameterized System Verification1999In: Proc. 11th Int. Conf. on Computer Aided Verification / [ed] Nicolas Halbwachs, Doron Peled, Berlin: Springer Verlag , 1999, p. 134-145Conference paper (Refereed)
    Abstract [en]

    We consider symbolic verification for a class of parameterized systems, where a system consists of a linear array of processes, and where an action of a process may in general be guarded by both local conditions restricting the state of the process about to perform the action, and global conditions defining the context in which the action is enabled. Such actions are present, e.g., in idealized versions of mutual exclusion protocols, such as the bakery and ticket algorithms by Lamport, Burn’s protocol, Dijkstra’s algorithm, and Szymanski’s algorithm. The presence of both local and global conditions makes the parameterized versions of these protocols infeasible to analyze fully automatically, using existing model checking methods for parameterized systems. In all these methods the actions are guarded only by local conditions involving the states of a finite set of processes. We perform verification using a standard symbolic reachability algorithm enhanced by an operation to accelerate the search of the state space. The acceleration operation computes the effect of an arbitrary number of applications of an action, rather than a single application. This is crucial for convergence of the analysis e.g. when applying the algorithm to the above protocols. We illustrate the use of our method through an application to Szymanski’s algorithm.

  • 118.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Cyriac, Aiswarya
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. Chennai Math Inst, Madras, Tamil Nadu, India..
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Data Communicating Processes with Unreliable Channels2016In: Proceedings Of The 31St Annual ACM-IEEE Symposium On Logic In Computer Science (LICS 2016), 2016, p. 166-175Conference paper (Refereed)
    Abstract [en]

    We extend the classical model of lossy channel systems by considering systems that operate on a finite set of variables ranging over an infinite data domain. Furthermore, each message inside a channel is equipped with a data item representing its value. Although we restrict the model by allowing the variables to be only tested for (dis-)equality, we show that the state reachability problem is undecidable. In light of this negative result, we consider bounded-phase reachability, where the processes are restricted to performing either send or receive operations during each phase. We show decidability of state reachability in this case by computing a symbolic encoding of the set of system configurations that are reachable from a given configuration.

  • 119.
    Abdulla, Parosh A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Delzanno, Giorgio
    Univ Genoa, DIBRIS, Genoa, Italy..
    Parameterized verification2016In: International Journal on Software Tools for Technology Transfer (STTT), ISSN 1433-2779, E-ISSN 1433-2787, Vol. 18, no 5, p. 469-473Article in journal (Other academic)
    Abstract [en]

    The goal of parameterized verification is to prove the correctness of a system specification regardless of the number of its components. The problem is of interest in several different areas: verification of hardware design, multithreaded programs, distributed systems, and communication protocols. The problem is undecidable in general. Solutions for restricted classes of systems and properties have been studied in areas like theorem proving, model checking, automata and logic, process algebra, and constraint solving. In this introduction to the special issue, dedicated to a selection of works from the Parameterized Verification workshop PV '14 and PV '15, we survey some of the works developed in this research area.

  • 120.
    Abdulla, Parosh A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Delzanno, Giorgio
    Univ Genoa, Genoa, Italy..
    Montali, Marco
    Free Univ Bolzano, Bolzano, Italy..
    Well Structured Transition Systems with History2015In: Electronic Proceedings in Theoretical Computer Science, ISSN 2075-2180, E-ISSN 2075-2180, no 193, p. 115-128Article in journal (Refereed)
    Abstract [en]

    We propose a formal model of concurrent systems in which the history of a computation is explicitly represented as a collection of events that provide a view of a sequence of configurations. In our model events generated by transitions become part of the system configurations leading to operational semantics with historical data. This model allows us to formalize what is usually done in symbolic verification algorithms. Indeed, search algorithms often use meta-information, e.g., names of fired transitions, selected processes, etc., to reconstruct (error) traces from symbolic state exploration. The other interesting point of the proposed model is related to a possible new application of the theory of well-structured transition systems (wsts). In our setting wsts theory can be applied to formally extend the class of properties that can be verified using coverability to take into consideration (ordered and unordered) historical data. This can be done by using different types of representation of collections of events and by combining them with wsts by using closure properties of well-quasi orderings.

  • 121.
    Abdulla, Parosh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Aronis, Stavros
    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.
    Sagonas, Konstantinos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Comparing source sets and persistent sets for partial order reduction2017In: Models, Algorithms, Logics and Tools: Essays Dedicated to Kim Guldstrand Larsen on the Occasion of His 60th Birthday, Springer, 2017, p. 516-536Chapter in book (Other academic)
    Abstract [en]

    Partial order reduction has traditionally been based on persistent sets, ample sets, stubborn sets, or variants thereof. Recently, we have presented a strengthening of this foundation, using source sets instead of persistent/ample/stubborn sets. Source sets subsume persistent sets and are often smaller than persistent sets. We introduced source sets as a basis for Dynamic Partial Order Reduction (DPOR), in a framework which assumes that processes are deterministic and that all program executions are finite. In this paper, show how to use source sets for partial order reduction in a framework which does not impose these restrictions. We also compare source sets with persistent sets, providing some insights into conditions under which source sets and persistent sets do or do not differ.

  • 122.
    Abdulla, Parosh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Aronis, Stavros
    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.
    Sagonas, Konstantinos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Optimal dynamic partial order reduction2014In: Proc. 41st ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages, New York: ACM Press, 2014, p. 373-384Conference paper (Refereed)
    Abstract [en]

    Stateless model checking is a powerful technique for program verification, which however suffers from an exponential growth in the number of explored executions. A successful technique for reducing this number, while still maintaining complete coverage, is Dynamic Partial Order Reduction (DPOR). We present a new DPOR algorithm, which is the first to be provably optimal in that it always explores the minimal number of executions. It is based on a novel class of sets, called source sets, which replace the role of persistent sets in previous algorithms. First, we show how to modify an existing DPOR algorithm to work with source sets, resulting in an efficient and simple to implement algorithm. Second, we extend this algorithm with a novel mechanism, called wakeup trees, that allows to achieve optimality. We have implemented both algorithms in a stateless model checking tool for Erlang programs. Experiments show that source sets significantly increase the performance and that wakeup trees incur only a small overhead in both time and space.

  • 123.
    Abdulla, Parosh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Aronis, Stavros
    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, Computing Science.
    Sagonas, Konstantinos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Source Sets: A Foundation for Optimal Dynamic Partial Order Reduction2017In: Journal of the ACM, ISSN 0004-5411, E-ISSN 1557-735X, Vol. 64, no 4, article id 25Article in journal (Refereed)
    Abstract [en]

    Stateless model checking is a powerful method for program verification that, however, suffers from an exponential growth in the number of explored executions. A successful technique for reducing this number, while still maintaining complete coverage, is Dynamic Partial Order Reduction (DPOR), an algorithm originally introduced by Flanagan and Godefroid in 2005 and since then not only used as a point of reference but also extended by various researchers. In this article, we present a new DPOR algorithm, which is the first to be provably optimal in that it always explores the minimal number of executions. It is based on a novel class of sets, called source sets, that replace the role of persistent sets in previous algorithms. We begin by showing how to modify the original DPOR algorithm to work with source sets, resulting in an efficient and simple-to-implement algorithm, called source-DPOR. Subsequently, we enhance this algorithm with a novel mechanism, called wakeup trees, that allows the resulting algorithm, called optimal-DPOR, to achieve optimality. Both algorithms are then extended to computational models where processes may disable each other, for example, via locks. Finally, we discuss tradeoffs of the source-and optimal-DPOR algorithm and present programs that illustrate significant time and space performance differences between them. We have implemented both algorithms in a publicly available stateless model checking tool for Erlang programs, while the source-DPOR algorithm is at the core of a publicly available stateless model checking tool for C/pthread programs running on machines with relaxed memory models. Experiments show that source sets significantly increase the performance of stateless model checking compared to using the original DPOR algorithm and that wakeup trees incur only a small overhead in both time and space in practice.

  • 124. Abdulla, Parosh Aziz
    Carrying Probabilities to the Infinite World2011In: CONCUR'2011, 22nd International Conference on Concurrency Theory., 2011Conference paper (Refereed)
  • 125.
    Abdulla, Parosh Aziz
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Forcing monotonicity in parameterized verification: From multisets to words2010In: SOFSEM 2010: Theory and Practice of Computer Science, Berlin: Springer-Verlag , 2010, p. 1-15Conference paper (Refereed)
  • 126.
    Abdulla, Parosh Aziz
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Regular model checking2012In: International Journal on Software Tools for Technology Transfer (STTT), ISSN 1385-4879, E-ISSN 1571-8115, Vol. 14, no 2, p. 109-118Article in journal (Refereed)
  • 127.
    Abdulla, Parosh Aziz
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Mathematics and Computer Science, Department of Information Technology. DEPARTMENT OF COMPUTER SYSTEMS.
    Using (Timed) Petri Nets for Verification of Parametrized (Timed) Systems2001In: VEPAS'2001, Verification of Parameterized Systems, 2001Conference paper (Refereed)
  • 128.
    Abdulla, Parosh Aziz
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Well (and better) quasi-ordered transition systems2010In: Bulletin of Symbolic Logic, ISSN 1079-8986, E-ISSN 1943-5894, Vol. 16, no 4, p. 457-515Article in journal (Refereed)
    Abstract [en]

    In this paper, we give a step by step introduction to the theory of well quasi-ordered transition systems. The framework combines two concepts, namely (i) transition systems which are monotonic wrt. a well-quasi ordering; and (ii) a scheme for symbolic backward reachability analysis. We describe several models with infinite-state spaces, which can be analyzed within the framework, e.g., Petri nets, lossy channel systems, timed automata, timed Petri nets, and multiset rewriting systems. We will also present better quasi-ordered transition systems which allow the design of efficient symbolic representations of infinite sets of states.

  • 129.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Aiswarya, C.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Montali, Marco
    Rezine, Othmane
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Complexity of reachability for data-aware dynamic systems2018In: Proc. 18th International Conference on Application of Concurrency to System Design, IEEE Computer Society, 2018, p. 11-20Conference paper (Refereed)
  • 130.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Aronis, Stavros
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Leonardsson, Carl
    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.
    Stateless model checking for TSO and PSO2015In: Tools and Algorithms for the Construction and Analysis of Systems: TACAS 2015, Springer Berlin/Heidelberg, 2015, p. 353-367Conference paper (Refereed)
  • 131.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Aronis, Stavros
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Leonardsson, Carl
    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.
    Stateless model checking for TSO and PSO2017In: Acta Informatica, ISSN 0001-5903, E-ISSN 1432-0525, Vol. 54, no 8, p. 789-818Article in journal (Refereed)
  • 132.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bouajjani, Ahmed
    Ngo, Tuan Phong
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A load-buffer semantics for total store ordering2018In: Logical Methods in Computer Science, ISSN 1860-5974, E-ISSN 1860-5974, Vol. 14, no 1, article id 9Article in journal (Refereed)
    Abstract [en]

    We address the problem of verifying safety properties of concurrent programs running over the Total Store Order (TSO) memory model. Known decision procedures for this model are based on complex encodings of store buffers as lossy channels. These procedures assume that the number of processes is fixed. However, it is important in general to prove the correctness of a system/algorithm in a parametric way with an arbitrarily large number of processes. 

    In this paper, we introduce an alternative (yet equivalent) semantics to the classical one for the TSO semantics that is more amenable to efficient algorithmic verification and for the extension to parametric verification. For that, we adopt a dual view where load buffers are used instead of store buffers. The flow of information is now from the memory to load buffers. We show that this new semantics allows (1) to simplify drastically the safety analysis under TSO, (2) to obtain a spectacular gain in efficiency and scalability compared to existing procedures, and (3) to extend easily the decision procedure to the parametric case, which allows obtaining a new decidability result, and more importantly, a verification algorithm that is more general and more efficient in practice than the one for bounded instances.

  • 133.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Bouajjani, Ahmed
    Ngo, Tuan Phong
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    The benefits of duality in verifying concurrent programs under TSO2016In: 27th International Conference on Concurrency Theory: CONCUR 2016, Dagstuhl, Germany: Leibniz-Zentrum für Informatik , 2016, p. 5:1-15Conference paper (Refereed)
    Abstract [en]

    We address the problem of verifying safety properties of concurrent programs running over the Total Store Order (TSO) memory model. Known decision procedures for this model are based on complex encodings of store buffers as lossy channels. These procedures assume that the number of processes is fixed. However, it is important in general to prove the correctness of a system/algorithm in a parametric way with an arbitrarily large number of processes.

    In this paper, we introduce an alternative (yet equivalent) semantics to the classical one for the TSO semantics that is more amenable to efficient algorithmic verification and for the extension to parametric verification. For that, we adopt a dual view where load buffers are used instead of store buffers. The flow of information is now from the memory to load buffers. We show that this new semantics allows (1) to simplify drastically the safety analysis under TSO, (2) to obtain a spectacular gain in efficiency and scalability compared to existing procedures, and (3) to extend easily the decision procedure to the parametric case, which allows obtaining a new decidability result, and more importantly, a verification algorithm that is more general and more efficient in practice than the one for bounded instances.

  • 134.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Cederberg, Jonathan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Analysis of message passing programs using SMT-solvers2013In: Automated Technology for Verification and Analysis: ATVA 2013, Springer Berlin/Heidelberg, 2013, p. 272-286Conference paper (Refereed)
  • 135.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Cederberg, Jonathan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Timed lossy channel systems2012In: IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science: FSTTCS 2012, Dagstuhl, Germany: Leibniz-Zentrum für Informatik , 2012, p. 374-386Conference paper (Refereed)
  • 136.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Cederberg, Jonathan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Modi, Subham
    Rezine, Othmane
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Saini, Gaurav
    MPass: An efficient tool for the analysis of message-passing programs2015In: Formal Aspects of Component Software, Springer, 2015, p. 198-206Conference paper (Refereed)
  • 137.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Chen, Yu-Fang
    Bui, Phi Diep
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Holik, Lukas
    Rezine, Ahmed
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Trau: SMT solver for string constraints2018In: The eighteenth in a series of conferences on the theory and applications of formal methods in hardware and system verification (FMCAD 2018), 2018Conference paper (Refereed)
  • 138.
    Abdulla, Parosh Aziz
    et al.
    Department of Information Technology, Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Department of Information Technology, Uppsala University, Sweden.
    Chen, Yu-Fang
    Institute of Information Science, Academia Sinica, Taiwan.
    Holik, Lukas
    Faculty of Information Technology, Brno University of Technology, Czech Republic.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Rümmer, Philipp
    Department of Information Technology, Uppsala University, Sweden.
    Stenman, Jari
    Department of Information Technology, Uppsala University, Sweden.
    String Constraints for Verification2014In: 26th International Conference on Computer Aided Verification (CAV 2014), Vienna, Austria, Jul. 9-12, 2014., Berlin: Springer, 2014, p. 150-166Conference paper (Refereed)
    Abstract [en]

    We present a decision procedure for a logic that combines (i) word equations over string variables denoting words of arbitrary lengths, together with (ii) constraints on the length of words, and on (iii) the regular languages to which words belong. Decidability of this general logic is still open. Our procedure is sound for the general logic, and a decision procedure for a particularly rich fragment that restricts the form in which word equations are written. In contrast to many existing procedures, our method does not make assumptions about the maximum length of words. We have developed a prototypical implementation of our decision procedure, and integrated it into a CEGAR-based model checker for the analysis of programs encoded as Horn clauses. Our tool is able to automatically establish the correctness of several programs that are beyond the reach of existing methods.

  • 139.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Chen, Yu-Fang
    Holík, Lukás
    Rezine, Ahmed
    Rümmer, Philipp
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Stenman, Jari
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Norn: An SMT solver for string constraints2015In: Computer Aided Verification: Part I, Springer, 2015, p. 462-469Conference paper (Refereed)
    Abstract [en]

    We present version 1.0 of the Norn SMT solver for string constraints. Norn is a solver for an expressive constraint language, including word equations, length constraints, and regular membership queries. As a feature distinguishing Norn from other SMT solvers, Norn is a decision procedure under the assumption of a set of acyclicity conditions on word equations, without any restrictions on the use of regular membership.

  • 140.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Chen, Yu-Fang
    Leonardsson, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rezine, Ahmed
    Automatic fence insertion in integer programs via predicate abstraction2012In: Static Analysis, Berlin: Springer-Verlag , 2012, p. 164-180Conference paper (Refereed)
  • 141.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academia Sinica, Taiwan.
    Leonardsson, Carl
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Automatic fence insertion in integer programs via predicate abstraction2012In: Static Analysis: 19th International Symposium, SAS 2012, Deauville, France, September 11-13, 2012. Proceedings / [ed] Antoine Miné, David Schmidt, Springer Berlin/Heidelberg, 2012, p. 164-180Conference paper (Refereed)
    Abstract [en]

    We propose an automatic fence insertion and verification framework for concurrent programs running under relaxed memory. Unlike previous approaches to this problem, which allow only variables of finite domain, we target programs with (unbounded) integer variables. The problem is difficult because it has two different sources of infiniteness: unbounded store buffers and unbounded integer variables. Our framework consists of three main components: (1) a finite abstraction technique for the store buffers, (2) a finite abstraction technique for the integer variables, and (3) a counterexample guided abstraction refinement loop of the model obtained from the combination of the two abstraction techniques. We have implemented a prototype based on the framework and run it successfully on all standard benchmarks together with several challenging examples that are beyond the applicability of existing methods.

  • 142.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Chen, Yu-Fang
    Leonardsson, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rezine, Ahmed
    Counter-Example Guided Fence Insertion under TSO2012In: Tools and Algorithms for the Construction and Analysis of Systems, Berlin: Springer-Verlag , 2012, p. 204-219Conference paper (Refereed)
  • 143.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academia Sinica, Taiwan.
    Leonardsson, Carl
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, ESLAB - Embedded Systems Laboratory. Linköping University, The Institute of Technology.
    Counter-Example Guided Fence Insertion under TSO2012In: TACAS 2012, Berlin, Heidelberg: Springer , 2012Conference paper (Refereed)
    Abstract [en]

    We give a sound and complete fence insertion procedure for concurrentfinite-state programs running under the classical TSO memory model. Thismodel allows “write to read” relaxation corresponding to the addition of an unboundedstore buffer between each processor and the main memory. We introducea novel machine model, called the Single-Buffer (SB) semantics, and show thatthe reachability problem for a program under TSO can be reduced to the reachabilityproblem under SB. We present a simple and effective backward reachabilityanalysis algorithm for the latter, and propose a counter-example guided fence insertionprocedure. The procedure is augmented by a placement constraint thatallows the user to choose places inside the program where fences may be inserted.For a given placement constraint, we automatically infer all minimal setsof fences that ensure correctness. We have implemented a prototype and run itsuccessfully on all standard benchmarks together with several challenging examplesthat are beyond the applicability of existing methods.

  • 144.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Chen, Yu-Fang
    Academia Sinica.
    Leonardsson, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Rezine, Ahmed
    Linköping University.
    MEMORAX, a Precise and Sound Tool for Automatic Fence Insertion under TSO2013In: Tools and Algorithms for the Construction and Analysis of Systems, Springer Berlin/Heidelberg, 2013, p. 530-536Conference paper (Refereed)
  • 145.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Sweden.
    Atig, Mohamed Faouzi
    Uppsala University, Sweden.
    Chen, Yu-Fang
    Academia Sinica, Taiwan.
    Leonardsson, Carl
    Uppsala University, Sweden.
    Rezine, Ahmed
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, The Institute of Technology.
    Memorax, a Precise and Sound Tool for Automatic Fence Insertion under TSO2013In: Tools and Algorithms for the Construction and Analysis of Systems: 19th International Conference, TACAS 2013, Held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2013, Rome, Italy, March 16-24, 2013. Proceedings, Springer Berlin/Heidelberg, 2013, p. 530-536Conference paper (Refereed)
    Abstract [en]

    We introduce MEMORAX, a tool for the verification of control state reachability (i.e., safety properties) of concurrent programs manipulating finite range and integer variables and running on top of weak memory models. The verification task is non-trivial as it involves exploring state spaces of arbitrary or even infinite sizes. Even for programs that only manipulate finite range variables, the sizes of the store buffers could grow unboundedly, and hence the state spaces that need to be explored could be of infinite size. In addition, MEMORAX in- corporates an interpolation based CEGAR loop to make possible the verification of control state reachability for concurrent programs involving integer variables. The reachability procedure is used to automatically compute possible memory fence placements that guarantee the unreachability of bad control states under TSO. In fact, for programs only involving finite range variables and running on TSO, the fence insertion functionality is complete, i.e., it will find all minimal sets of memory fence placements (minimal in the sense that removing any fence would result in the reachability of the bad control states). This makes MEMORAX the first freely available, open source, push-button verification and fence insertion tool for programs running under TSO with integer variables.

  • 146.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ciobanu, Radu
    Mayr, Richard
    Totzke, Patrick
    Universal safety for timed Petri nets is PSPACE-complete2018In: 29th International Conference on Concurrency Theory, Dagstuhl, Germany: Leibniz-Zentrum für Informatik , 2018, p. 6:1-15Conference paper (Refereed)
  • 147.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Delzanno, Giorgio
    Podelski, Andreas
    Push-down automata with gap-order constraints2013In: Fundamentals of Software Engineering: FSEN 2013, Springer Berlin/Heidelberg, 2013, p. 199-216Conference paper (Refereed)
  • 148.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ganjei, Zeinab
    Rezine, Ahmed
    Zhu, Yunyun
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Verification of Cache Coherence Protocols wrt. Trace Filters2015In: Proc. 15th Conference on Formal Methods in Computer-Aided Design, Piscataway, NJ: IEEE , 2015, p. 9-16Conference paper (Refereed)
  • 149.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Leonardsson, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Stateless model checking for POWER2016In: Computer Aided Verification: Part II, Springer, 2016, p. 134-156Conference paper (Refereed)
    Abstract [en]

    We present the first framework for efficient application of stateless model checking (SMC) to programs running under the relaxed memory model of POWER. The framework combines several contributions. The first contribution is that we develop a scheme for systematically deriving operational execution models from existing axiomatic ones. The scheme is such that the derived execution models are well suited for efficient SMC. We apply our scheme to the axiomatic model of POWER from [8]. Our main contribution is a technique for efficient SMC, called Relaxed Stateless Model Checking (RSMC), which systematically explores the possible inequivalent executions of a program. RSMC is suitable for execution models obtained using our scheme. We prove that RSMC is sound and optimal for the POWER memory model, in the sense that each complete program behavior is explored exactly once. We show the feasibility of our technique by providing an implementation for programs written in C/pthreads.

  • 150.
    Abdulla, Parosh Aziz
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Atig, Mohamed Faouzi
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kara, Ahmet
    Rezine, Othmane
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Verification of buffered dynamic register automata2015In: Networked Systems: NETYS 2015, Springer, 2015, p. 15-31Conference paper (Refereed)
1234567 101 - 150 of 51455
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