Download or read book Automatic Verification of Parameterized Systems by Over Approximation written by Vladislavs Jahundovics and published by Linköping University Electronic Press. This book was released on 2015-11-17 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a completely automatic verification framework to check safety properties of parameterized systems. A parameterized system is a family of finite state systems where every system consists of a finite number of processes running in parallel the same algorithm. All the systems in the family differ only in the number of the processes and, in general, the number of systems in a family may be unbounded. Examples of parameterized systems are communication protocols, mutual exclusion protocols, cache coherence protocols, distributed algorithms etc. Model-checking of finite state systems is a well-developed formal verification approach of proving properties of systems in an automatic way. However, it cannot be applied directly to parameterized systems because the unbounded number of systems in a family means an infinite state space. In this thesis we propose to abstract an original family of systems consisting of an unbounded number of processes into one consisting of a fixed number of processes. An abstracted system is considered to consist of k+1 components—k reference processes and their environment. The transition relation for the abstracted system is an over-approximation of the transition relation for the original system, therefore, a set of reachable states of the abstracted system is an over-approximation of the set of reachable states of the original one. A safety property is considered to be parameterized by a fixed number of processes whose relationship is in the center of attention in the property. Such processes serve as reference processes in the abstraction. We propose an encoding which allows to perform reachability analysis for an abstraction parameterized by the reference processes. We have successfully verified three classic parameterized systems with replicated processes by applying this method.
Download or read book Automatic Verification of Parameterized Systems written by Jiazhao (Jessie). Xu and published by . This book was released on 2005 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Formal Verification of Tree Ensembles in Safety Critical Applications written by John Törnblom and published by Linköping University Electronic Press. This book was released on 2020-10-28 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the presence of data and computational resources, machine learning can be used to synthesize software automatically. For example, machines are now capable of learning complicated pattern recognition tasks and sophisticated decision policies, two key capabilities in autonomous cyber-physical systems. Unfortunately, humans find software synthesized by machine learning algorithms difficult to interpret, which currently limits their use in safety-critical applications such as medical diagnosis and avionic systems. In particular, successful deployments of safety-critical systems mandate the execution of rigorous verification activities, which often rely on human insights, e.g., to identify scenarios in which the system shall be tested. A natural pathway towards a viable verification strategy for such systems is to leverage formal verification techniques, which, in the presence of a formal specification, can provide definitive guarantees with little human intervention. However, formal verification suffers from scalability issues with respect to system complexity. In this thesis, we investigate the limits of current formal verification techniques when applied to a class of machine learning models called tree ensembles, and identify model-specific characteristics that can be exploited to improve the performance of verification algorithms when applied specifically to tree ensembles. To this end, we develop two formal verification techniques specifically for tree ensembles, one fast and conservative technique, and one exact but more computationally demanding. We then combine these two techniques into an abstraction-refinement approach, that we implement in a tool called VoTE (Verifier of Tree Ensembles). Using a couple of case studies, we recognize that sets of inputs that lead to the same system behavior can be captured precisely as hyperrectangles, which enables tractable enumeration of input-output mappings when the input dimension is low. Tree ensembles with a high-dimensional input domain, however, seems generally difficult to verify. In some cases though, conservative approximations of input-output mappings can greatly improve performance. This is demonstrated in a digit recognition case study, where we assess the robustness of classifiers when confronted with additive noise.
Download or read book Verification Model Checking and Abstract Interpretation written by Francesco Logozzo and published by Springer Science & Business Media. This book was released on 2008-02-26 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book constitutes the refereed proceedings of the 9th International Conference on Verification, Model Checking, and Abstract Interpretation, VMCAI 2007, held in San Francisco, USA, in January 2008. The 21 revised full papers presented together with 2 invited lectures and 2 invited tutorials were carefully reviewed and selected from a total of over 60 submissions. The papers feature current research from the communities of verification, program certification, model checking, debugging techniques, abstract interpretation, abstract domains, static analysis, cross-fertilization, and advancement of hybrid methods.
Download or read book Designing a Modern Skeleton Programming Framework for Parallel and Heterogeneous Systems written by August Ernstsson and published by Linköping University Electronic Press. This book was released on 2020-10-21 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today's society is increasingly software-driven and dependent on powerful computer technology. Therefore it is important that advancements in the low-level processor hardware are made available for exploitation by a growing number of programmers of differing skill level. However, as we are approaching the end of Moore's law, hardware designers are finding new and increasingly complex ways to increase the accessible processor performance. It is getting more and more difficult to effectively target these processing resources without expert knowledge in parallelization, heterogeneous computation, communication, synchronization, and so on. To ensure that the software side can keep up, advanced programming environments and frameworks are needed to bridge the widening gap between hardware and software. One such example is the pattern-centric skeleton programming model and in particular the SkePU project. The work presented in this thesis first redesigns the SkePU framework based on modern C++ variadic template metaprogramming and state-of-the-art compiler technology. It then explores new ways to improve performance: by providing new patterns, improving the data access locality of existing ones, and using both static and dynamic knowledge about program flow. The work combines novel ideas with practical evaluation of the approach on several applications. The advancements also include the first skeleton API that allows variadic skeletons, new data containers, and finally an approach to make skeleton programming more customizable without compromising universal portability.
Download or read book Formal Techniques for Networked and Distributed Systems FORTE 2008 written by Kenji Suzuki and published by Springer Science & Business Media. This book was released on 2008-05-27 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of FORTE 2008, 28th IFIP WG6.1 - ternational Conference on Formal Techniques for Networked and Distributed Systems. FORTE 2008 was held at the Campus Innovation Center in Tokyo, Japan during June 10–13, 2008. FORTE denotes a series of international wo- ing conferences on formal description techniques applied to computer networks and distributed systems. The conference series started in 1981 under the name PSTV. In 1988 a second series under the name FORTE was set up. Both - ries were united to FORTE/PSTV in 1996. In 2001 the conference changed the name to its current form. Recent conferences of this long series were held in Berlin (2003), Madrid(2004), Taipei(2005), Paris(2006), and Tallinn(2007). As in the previous year, FORTE 2008 was collocated with TESTCOM/ FATES 2008: the 20th IFIP International Conference on Testing of Com- nicating Systems (TESTCOM) and the 8th International Workshop on Formal Approaches to Testing of Software (FATES). The co-location of FORTE and TESTCOM/FATES fostered the collaboration between their communities. The commonspiritofboth conferenceswasunderpinnedby jointopening andclosing sessions, invited talks, as well as joint social events.
Download or read book Parameterized Systems written by and published by . This book was released on 2008 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theoretical Aspects of Computing ICTAC 2008 written by John S. Fitzgerald and published by Springer. This book was released on 2008-08-25 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on theoretical aspects of computing has a direct impact on the pr- tice of computer systems development. Over many decades, fundamental t- ories have emerged to describe functionality, temporal behavior and resource consumption. Theories of application domains are beginning to be exploited for modelling and analyzing intended computing systems before the expensive c- mitment is made to real programs and hardware. Recent years have seen major improvements in the cost-e?ectiveness of tools supporting the exploitation of theories through proof, model-checking and testing. Against this encouraging background, we are pleased to present papers that show something of the live- ness and diversity of research in theoretical aspects of computing today. ICTAC 2008, the 5th International Colloquium on Theoretical Aspects of Computing, was held on 1-3 September 2008 in Istanbul, Turkey, hosted by - banc? University. The ICTAC series was founded by the International Institute for SoftwareTechnologyof the United Nations University(UNU-IIST). It brings together practitioners and researchers from academia, industry and government to present results and to exchange ideas and experience addressing challenges in both theoretical aspects of computing and in the exploitation of theory through methodsandtoolsforsystemdevelopment. Theseriesalsopromotescooperation in research and education between participants and their institutions, from - veloping and industrial countries, in accordance with the mandate of the United Nations University. The previous ICTAC colloquia were held in Guiyang, China (2004, LNCS 3407), Hanoi, Vietnam (2005, LNCS 3722), Tunis, Tunisia (2006, LNCS 4281) and Macau SAR, China (2007, LNCS 4711).
Download or read book Extensions for Distributed Moving Base Driving Simulators written by Anders Andersson and published by Linköping University Electronic Press. This book was released on 2017-03-30 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern vehicles are complex systems. Different design stages for such a complex system include evaluation using models and submodels, hardware-in-the-loop systems and complete vehicles. Once a vehicle is delivered to the market evaluation continues by the public. One kind of tool that can be used during many stages of a vehicle lifecycle is driving simulators. The use of driving simulators with a human driver is commonly focused on driver behavior. In a high fidelity moving base driving simulator it is possible to provide realistic and repetitive driving situations using distinctive features such as: physical modelling of driven vehicle, a moving base, a physical cabin interface and an audio and visual representation of the driving environment. A desired but difficult goal to achieve using a moving base driving simulator is to have behavioral validity. In other words, A driver in a moving base driving simulator should have the same driving behavior as he or she would have during the same driving task in a real vehicle.". In this thesis the focus is on high fidelity moving base driving simulators. The main target is to improve the behavior validity or to maintain behavior validity while adding complexity to the simulator. One main assumption in this thesis is that systems closer to the final product provide better accuracy and are perceived better if properly integrated. Thus, the approach in this thesis is to try to ease incorporation of such systems using combinations of the methods hardware-in-the-loop and distributed simulation. Hardware-in-the-loop is a method where hardware is interfaced into a software controlled environment/simulation. Distributed simulation is a method where parts of a simulation at physically different locations are connected together. For some simulator laboratories distributed simulation is the only feasible option since some hardware cannot be moved in an easy way. Results presented in this thesis show that a complete vehicle or hardware-in-the-loop test laboratory can successfully be connected to a moving base driving simulator. Further, it is demonstrated that using a framework for distributed simulation eases communication and integration due to standardized interfaces. One identified potential problem is complexity in interface wrappers when integrating hardware-in-the-loop in a distributed simulation framework. From this aspect, it is important to consider the model design and the intersections between software and hardware models. Another important issue discussed is the increased delay in overhead time when using a framework for distributed simulation.
Download or read book Methods and Tools for Efficient Model Based Development of Cyber Physical Systems with Emphasis on Model and Tool Integration written by Alachew Mengist and published by Linköping University Electronic Press. This book was released on 2019-08-21 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: Model-based tools and methods are playing important roles in the design and analysis of cyber-physical systems before building and testing physical prototypes. The development of increasingly complex CPSs requires the use of multiple tools for different phases of the development lifecycle, which in turn depends on the ability of the supporting tools to interoperate. However, currently no vendor provides comprehensive end-to-end systems engineering tool support across the entire product lifecycle, and no mature solution currently exists for integrating different system modeling and simulation languages, tools and algorithms in the CPSs design process. Thus, modeling and simulation tools are still used separately in industry. The unique challenges in integration of CPSs are a result of the increasing heterogeneity of components and their interactions, increasing size of systems, and essential design requirements from various stakeholders. The corresponding system development involves several specialists in different domains, often using different modeling languages and tools. In order to address the challenges of CPSs and facilitate design of system architecture and design integration of different models, significant progress needs to be made towards model-based integration of multiple design tools, languages, and algorithms into a single integrated modeling and simulation environment. In this thesis we present the need for methods and tools with the aim of developing techniques for numerically stable co-simulation, advanced simulation model analysis, simulation-based optimization, and traceability capability, and making them more accessible to the model-based cyber physical product development process, leading to more efficient simulation. In particular, the contributions of this thesis are as follows: 1) development of a model-based dynamic optimization approach by integrating optimization into the model development process; 2) development of a graphical co-modeling editor and co-simulation framework for modeling, connecting, and unified system simulation of several different modeling tools using the TLM technique; 3) development of a tool-supported method for multidisciplinary collaborative modeling and traceability support throughout the development process for CPSs; 4) development of an advanced simulation modeling analysis tool for more efficient simulation.
Download or read book Towards Semantically Enabled Complex Event Processing written by Robin Keskisärkkä and published by Linköping University Electronic Press. This book was released on 2017-10-30 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Semantic Web provides a framework for semantically annotating data on the web, and the Resource Description Framework (RDF) supports the integration of structured data represented in heterogeneous formats. Traditionally, the Semantic Web has focused primarily on more or less static data, but information on the web today is becoming increasingly dynamic. RDF Stream Processing (RSP) systems address this issue by adding support for streaming data and continuous query processing. To some extent, RSP systems can be used to perform complex event processing (CEP), where meaningful high-level events are generated based on low-level events from multiple sources; however, there are several challenges with respect to using RSP in this context. Event models designed to represent static event information lack several features required for CEP, and are typically not well suited for stream reasoning. The dynamic nature of streaming data also greatly complicates the development and validation of RSP queries. Therefore, reusing queries that have been prepared ahead of time is important to be able to support real-time decision-making. Additionally, there are limitations in existing RSP implementations in terms of both scalability and expressiveness, where some features required in CEP are not supported by any of the current systems. The goal of this thesis work has been to address some of these challenges and the main contributions of the thesis are: (1) an event model ontology targeted at supporting CEP; (2) a model for representing parameterized RSP queries as reusable templates; and (3) an architecture that allows RSP systems to be integrated for use in CEP. The proposed event model tackles issues specifically related to event modeling in CEP that have not been sufficiently covered by other event models, includes support for event encapsulation and event payloads, and can easily be extended to fit specific use-cases. The model for representing RSP query templates was designed as an extension to SPIN, a vocabulary that supports modeling of SPARQL queries as RDF. The extended model supports the current version of the RSP Query Language (RSP-QL) developed by the RDF Stream Processing Community Group, along with some of the most popular RSP query languages. Finally, the proposed architecture views RSP queries as individual event processing agents in a more general CEP framework. Additional event processing components can be integrated to provide support for operations that are not supported in RSP, or to provide more efficient processing for specific tasks. We demonstrate the architecture in implementations for scenarios related to traffic-incident monitoring, criminal-activity monitoring, and electronic healthcare monitoring.
Download or read book Tools and Algorithms for the Construction and Analysis of Systems written by Susanne Graf and published by Springer. This book was released on 2003-06-29 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 6th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2000, held as part of ETAPS 2000 in Berlin, Germany, in March/April 2000. The 33 revised full papers presented together with one invited paper and two short tool descriptions were carefully reviewed and selected from a total of 107 submissions. The papers are organized in topical sections on software and formal methods, formal methods, timed and hybrid systems, infinite and parameterized systems, diagnostic and test generation, efficient model checking, model-checking tools, symbolic model checking, visual tools, and verification of critical systems.
Download or read book Spatio Temporal Stream Reasoning with Adaptive State Stream Generation written by Daniel de Leng and published by Linköping University Electronic Press. This book was released on 2017-09-08 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: A lot of today's data is generated incrementally over time by a large variety of producers. This data ranges from quantitative sensor observations produced by robot systems to complex unstructured human-generated texts on social media. With data being so abundant, making sense of these streams of data through reasoning is challenging. Reasoning over streams is particularly relevant for autonomous robotic systems that operate in a physical environment. They commonly observe this environment through incremental observations, gradually refining information about their surroundings. This makes robust management of streaming data and its refinement an important problem. Many contemporary approaches to stream reasoning focus on the issue of querying data streams in order to generate higher-level information by relying on well-known database approaches. Other approaches apply logic-based reasoning techniques, which rarely consider the provenance of their symbolic interpretations. In this thesis, we integrate techniques for logic-based spatio-temporal stream reasoning with the adaptive generation of the state streams needed to do the reasoning over. This combination deals with both the challenge of reasoning over streaming data and the problem of robustly managing streaming data and its refinement. The main contributions of this thesis are (1) a logic-based spatio-temporal reasoning technique that combines temporal reasoning with qualitative spatial reasoning; (2) an adaptive reconfiguration procedure for generating and maintaining a data stream required to perform spatio-temporal stream reasoning over; and (3) integration of these two techniques into a stream reasoning framework. The proposed spatio-temporal stream reasoning technique is able to reason with intertemporal spatial relations by leveraging landmarks. Adaptive state stream generation allows the framework to adapt in situations in which the set of available streaming resources changes. Management of streaming resources is formalised in the DyKnow model, which introduces a configuration life-cycle to adaptively generate state streams. The DyKnow-ROS stream reasoning framework is a concrete realisation of this model that extends the Robot Operating System (ROS). DyKnow-ROS has been deployed on the SoftBank Robotics NAO platform to demonstrate the system's capabilities in the context of a case study on run-time adaptive reconfiguration. The results show that the proposed system – by combining reasoning over and reasoning about streams – can robustly perform spatio-temporal stream reasoning, even when the availability of streaming resources changes.
Download or read book Latency aware Resource Management at the Edge written by Klervie Toczé and published by Linköping University Electronic Press. This book was released on 2020-02-19 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increasing diversity of connected devices leads to new application domains being envisioned. Some of these need ultra low latency or have privacy requirements that cannot be satisfied by the current cloud. By bringing resources closer to the end user, the recent edge computing paradigm aims to enable such applications. One critical aspect to ensure the successful deployment of the edge computing paradigm is efficient resource management. Indeed, obtaining the needed resources is crucial for the applications using the edge, but the resource picture of this paradigm is complex. First, as opposed to the nearly infinite resources provided by the cloud, the edge devices have finite resources. Moreover, different resource types are required depending on the applications and the devices supplying those resources are very heterogeneous. This thesis studies several challenges towards enabling efficient resource management for edge computing. The thesis begins by a review of the state-of-the-art research focusing on resource management in the edge computing context. A taxonomy is proposed for providing an overview of the current research and identify areas in need of further work. One of the identified challenges is studying the resource supply organization in the case where a mix of mobile and stationary devices is used to provide the edge resources. The ORCH framework is proposed as a means to orchestrate this edge device mix. The evaluation performed in a simulator shows that this combination of devices enables higher quality of service for latency-critical tasks. Another area is understanding the resource demand side. The thesis presents a study of the workload of a killer application for edge computing: mixed reality. The MR-Leo prototype is designed and used as a vehicle to understand the end-to-end latency, the throughput, and the characteristics of the workload for this type of application. A method for modeling the workload of an application is devised and applied to MR-Leo in order to obtain a synthetic workload exhibiting the same characteristics, which can be used in further studies.
Download or read book Exploring C2 Capability and Effectiveness in Challenging Situations written by Magdalena Granåsen and published by Linköping University Electronic Press. This book was released on 2019-05-27 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern societies are affected by various threats and hazards, including natural disasters, cyber-attacks, extreme weather events and inter-state conflicts. Managing these challenging situations requires immediate actions, suspension of ordinary procedures, decision making under uncertainty and coordinated action. In other words, challenging situations put high demands on the command and control (C2) capability. To strengthen the capability of C2, it is vital to identify the prerequisites for effective coordination and direction within the domain of interest. This thesis explores C2 capability and effectiveness in three domains: interorganizational crisis management, military command and control, and cyber defence operations. The thesis aims to answer three research questions: (1) What constitutes C2 capability? (2) What constitutes C2 effectiveness? and (3) How can C2 effectiveness be assessed? The work was carried out as two case studies and one systematic literature review. The main contributions of the thesis are the identification of perspectives of C2 capability in challenging situations and an overview of approaches to C2 effectiveness assessment. Based on the results of the three studies, six recurring perspectives of capability in the domains studied were identified: interaction (collaboration), direction and coordination, relationships, situation awareness, resilience and preparedness. In the domains there are differences concerning which perspectives that are most emphasized in order obtain C2 capability. C2 effectiveness is defined as the extent to which a C2 system is successful in achieving its intended result. The thesis discusses the interconnectedness of performance and effectiveness measures, and concludes that there is not a united view on the difference between measures of effectiveness and measures of performance. Different approaches to effectiveness assessment were identified, where assessment may be conducted based on one specific issue, in relation to a defined goal for a C2 function or using a more exploratory approach.
Download or read book Parameterized Verification of Synchronized Concurrent Programs written by Zeinab Ganjei and published by Linköping University Electronic Press. This book was released on 2021-03-19 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is currently an increasing demand for concurrent programs. Checking the correctness of concurrent programs is a complex task due to the interleavings of processes. Sometimes, violation of the correctness properties in such systems causes human or resource losses; therefore, it is crucial to check the correctness of such systems. Two main approaches to software analysis are testing and formal verification. Testing can help discover many bugs at a low cost. However, it cannot prove the correctness of a program. Formal verification, on the other hand, is the approach for proving program correctness. Model checking is a formal verification technique that is suitable for concurrent programs. It aims to automatically establish the correctness (expressed in terms of temporal properties) of a program through an exhaustive search of the behavior of the system. Model checking was initially introduced for the purpose of verifying finite‐state concurrent programs, and extending it to infinite‐state systems is an active research area. In this thesis, we focus on the formal verification of parameterized systems. That is, systems in which the number of executing processes is not bounded a priori. We provide fully-automatic and parameterized model checking techniques for establishing the correctness of safety properties for certain classes of concurrent programs. We provide an open‐source prototype for every technique and present our experimental results on several benchmarks. First, we address the problem of automatically checking safety properties for bounded as well as parameterized phaser programs. Phaser programs are concurrent programs that make use of the complex synchronization construct of Habanero Java phasers. For the bounded case, we establish the decidability of checking the violation of program assertions and the undecidability of checking deadlock‐freedom. For the parameterized case, we study different formulations of the verification problem and propose an exact procedure that is guaranteed to terminate for some reachability problems even in the presence of unbounded phases and arbitrarily many spawned processes. Second, we propose an approach for automatic verification of parameterized concurrent programs in which shared variables are manipulated by atomic transitions to count and synchronize the spawned processes. For this purpose, we introduce counting predicates that related counters that refer to the number of processes satisfying some given properties to the variables that are directly manipulated by the concurrent processes. We then combine existing works on the counter, predicate, and constrained monotonic abstraction and build a nested counterexample‐based refinement scheme to establish correctness. Third, we introduce Lazy Constrained Monotonic Abstraction for more efficient exploration of well‐structured abstractions of infinite‐state non‐monotonic systems. We propose several heuristics and assess the efficiency of the proposed technique by extensive experiments using our open‐source prototype. Lastly, we propose a sound but (in general) incomplete procedure for automatic verification of safety properties for a class of fault‐tolerant distributed protocols described in the Heard‐Of (HO for short) model. The HO model is a popular model for describing distributed protocols. We propose a verification procedure that is guaranteed to terminate even for unbounded number of the processes that execute the distributed protocol.
Download or read book Tools and Algorithms for the Construction and Analysis of Systems written by Tiziana Margaria and published by Springer. This book was released on 2003-06-29 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 7th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2001. The 36 revised full papers presented together with an invited contribution were carefully reviewed and selected from a total of 125 submissions. The papers are organized in sections on symbolic verification, infinite state systems - deduction and abstraction, application of model checking techniques, timed and probabilistic systems, hardware - design and verification, software verification, testing - techniques and tools, implementation techniques, semantics and compositional verification, logics and model checking, and ETAPS tool demonstration.
