There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

ing WS1S Systems to Verify Parameterized Networks . . . . . . . . . . . . 188 Kai Baukus, Saddek Bensalem, Yassine Lakhnech and Karsten Stahl FMona: A Tool for Expressing Validation Techniques over Infinite State Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 J.-P. Bodeveix and M. Filali Transitive Closures of Regular Relations for Verifying Infinite-State Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 Bengt Jonsson and Marcus Nilsson Diagnostic and Test Generation Using Static Analysis to Improve Automatic Test Generation . . . . . . . . . . . . . 235 Marius Bozga, Jean-Claude Fernandez and Lucian Ghirvu Efficient Diagnostic Generation for Boolean Equation Systems . . . . . . . . . . . . 251 Radu Mateescu Efficient Model-Checking Compositional State Space Generation with Partial Order Reductions for Asynchronous Communicating Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266 Jean-Pierre Krimm and Laurent Mounier Checking for CFFD-Preorder with Tester Processes . . . . . . . . . . . . . . . . . . . . . . . 283 Juhana Helovuo and Antti Valmari Fair Bisimulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 Thomas A. Henzinger and Sriram K. Rajamani Integrating Low Level Symmetries into Reachability Analysis . . . . . . . . . . . . . 315 Karsten Schmidt Model-Checking Tools Model Checking Support for the ASM High-Level Language . . . . . . . . . . . . . . 331 Giuseppe Del Castillo and Kirsten Winter Table of

Tools and Algorithms for the Construction and Analysis of Systems. Proc. TACAS 2009

技術解説 IEEE Computer

A monolithically integrated semiconductor circuit, provided for coupling arrangements having symmetrical cross points, comprising two through switching NPN transistors, and a composite circuit for switching through the switching transistors. The composite circuit includes a double collector PNP transistor, with one collector connected to the base of a first NPN transistor and the other collector connected to the base of a second NPN transistor. The emitter of the double collector transistor is connected to the collector of both NPN transistors and also, via a first resistor to a voltage source. The base of the double collector transistor is connected, via a component causing a constant drop in voltage, to the voltage source, and also via a second resistor, to a trigger stage. The emitters of the NPN transistor are connected, respectively, to the bases of the two through switching transistors.

Parallel Program Design

The paper presents, and discusses the rationale behind, a method for structuring complex computing systems by the use of what we term “recovery blocks”, “conversations” and “fault-tolerant interfaces”. The aim is to facilitate the provision of dependable error detection and recovery facilities which can cope with errors caused by residual design inadequacies, particularly in the system software, rather than merely the occasional malfunctioning of hardware components.

System Structure for Software Fault Tolerance

The architecture of a system describes the system’s overall organization into components and connections between those components. With the emergence of mobile computing, dynamic architectures became increasingly important. In such architectures, components may appear or disappear, and connections may change over time.

Specifying Properties of Dynamic Architectures Using Configuration Traces

Formal methods (FMs) have been around for a while, still being unclear how to leverage their benefits, overcome their challenges, and set new directions for their improvement towards a more successful transfer into practice. We study the use of formal methods in mission-critical software domains, examining industrial and academic views. We perform a cross-sectional on-line survey. Our results indicate an increased intent to apply FMs in industry, suggesting a positively perceived usefulness. But the results also indicate a negatively perceived ease of use. Scalability, skills, and education seem to be among the key challenges to support this intent. We present the largest study of this kind so far (N = 216), and our observations provide valuable insights, highlighting directions for future theoretical and empirical research of formal methods. Our findings are strongly coherent with earlier observations by Austin and Graeme (1993).

/pdf/formal-methods-in-dependable-systems-engineering-a-survey-of-1sggvhhvud.pdf

Formal methods in dependable systems engineering: a survey of professionals from Europe and North America

Context: Formal methods (FMs) have been around for a while, still being unclear how to leverage their benefits, overcome their challenges, and set new directions for their improvement towards a more successful transfer into practice. Objective: We study the use of formal methods in mission-critical software domains, examining industrial and academic views. Method: We perform a cross-sectional on-line survey. Results: Our results indicate an increased intent to apply FMs in industry, suggesting a positively perceived usefulness. But the results also indicate a negatively perceived ease of use. Scalability, skills, and education seem to be among the key challenges to support this intent. Conclusions: We present the largest study of this kind so far (N = 216), and our observations provide valuable insights, highlighting directions for future theoretical and empirical research of formal methods. Our findings are strongly coherent with earlier observations by Austin and Parkin (1993).

/pdf/formal-methods-in-dependable-systems-engineering-a-survey-of-umxbl6ufxy.pdf

Formal Methods in Dependable Systems Engineering: A Survey of Professionals from Europe and North America

The architecture of a system describes the system’s overall organization into components and connections between those components. With the emergence of mobile computing, dynamic architectures became increasingly important. In such architectures, components may appear or disappear, and connections may change over time. Despite the growing importance of dynamic architectures, the specification of properties for those architectures remains a challenge. To address this problem, we introduce the notion of configuration traces to model properties of dynamic architectures. Then, we characterize activation, connection, and behavior properties as special sets of configuration traces. We then show soundness and relative completeness of our characterization, i.e., we show that the intersection of an activation, connection, and behavior property contains all relevant configuration traces and that (almost) every property can be separated into these classes. Configuration traces can be used to specify general properties of dynamic architectures and the separation into different classes provides a systematic way for their specification. To evaluate our approach we apply it to the specification and verification of the Blackboard architecture pattern.

On Activation, Connection, and Behavior in Dynamic Architectures

Architectural styles and patterns play an important role in software engineering. Over the last years, a new style based on the notion of services emerged, which we call the service-oriented architecture style. However, this style is usually only stated informally, which may cause inherent problems such as ambiguity, wrong conclusions, and the difficulty of checking the conformance of a system to the style. We address these problems by providing a formal, denotational semantics of the service-oriented architecture style and two variants thereof: the layered architecture style and the strict architecture style. Loosely speaking, in our model of the service-oriented architecture style, services are a means of communication. Components exchange services between each other via ports. The layered architecture variant imposes a well-foundedness constraint on the communication structure, while the strict variant imposes an antitransitivity constraint. We analyze the notions of syntactic and semantic dependencies for service-oriented architectures and investigate their relationship. Moreover, the expected informal properties of the styles are formulated as theorems. Finally, we present a method for soundly analyzing instances of the style. Our rigorous approach enables building higher-quality architectures, for which properties can be mathematically stated and proven, by enforcing formal discipline on the inter-component scale.

/pdf/a-model-of-service-oriented-architectures-3e8n8en8ie.pdf

Diego Marmsoler

Papers

Specifying Properties of Dynamic Architectures Using Configuration Traces

Formal methods in dependable systems engineering: a survey of professionals from Europe and North America

Formal Methods in Dependable Systems Engineering: A Survey of Professionals from Europe and North America

On Activation, Connection, and Behavior in Dynamic Architectures

A Model of Service-Oriented Architectures