8 research outputs found

    Constraint Diagrams: Visualizing Invariants in OO Modelling

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    A new visual notation is proposed for precisely expressing constraints on object-oriented models, as an alternative to mathematical logic notation used in methods such as Syntropy and Catalysis. The notation is potentially intuitive, expressive, integrates well with existing visual notations, and has a clear and unambiguous semantics. It is reminiscent of informal diagrams used by mathematicians for illustrating relations, and borrows much from Venn diagrams. It may be viewed as a generalization of instance diagrams

    Constraint Diagrams: Visualizing Assertions in OO Modelling

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    Describes a notation, constraint diagrams, which allows pre/post conditions and invariants to be expressed visually, rather than in the notation of mathematical logic. The notation is explored through a small case study (a library system). Some conclusions are drawn about the use of the notation in modelling, and its possible impact on tools and semantics. This report has been split into two and considerable revised and updated: Kent (1997b), Kent (1997c)

    Fourth NASA Langley Formal Methods Workshop

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    This publication consists of papers presented at NASA Langley Research Center's fourth workshop on the application of formal methods to the design and verification of life-critical systems. Topic considered include: Proving properties of accident; modeling and validating SAFER in VDM-SL; requirement analysis of real-time control systems using PVS; a tabular language for system design; automated deductive verification of parallel systems. Also included is a fundamental hardware design in PVS

    Formal Methods Specification and Analysis Guidebook for the Verification of Software and Computer Systems

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    This guidebook, the second of a two-volume series, is intended to facilitate the transfer of formal methods to the avionics and aerospace community. The 1st volume concentrates on administrative and planning issues [NASA-95a], and the second volume focuses on the technical issues involved in applying formal methods to avionics and aerospace software systems. Hereafter, the term "guidebook" refers exclusively to the second volume of the series. The title of this second volume, A Practitioner's Companion, conveys its intent. The guidebook is written primarily for the nonexpert and requires little or no prior experience with formal methods techniques and tools. However, it does attempt to distill some of the more subtle ingredients in the productive application of formal methods. To the extent that it succeeds, those conversant with formal methods will also nd the guidebook useful. The discussion is illustrated through the development of a realistic example, relevant fragments of which appear in each chapter. The guidebook focuses primarily on the use of formal methods for analysis of requirements and high-level design, the stages at which formal methods have been most productively applied. Although much of the discussion applies to low-level design and implementation, the guidebook does not discuss issues involved in the later life cycle application of formal methods

    From specification through refinement to implementation : a comparative study

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    This dissertation investigates the role of specification, refinement and implementation in the software development cycle. Both the structured and object-oriented paradigms are looked at. Particular emphasis is placed on the role of the refinement process. The requirements for the product (system) are determined, the specifications are drawn up, the product is designed, specified, implemented and tested. The stage between the (formal) specification of the system and the implementation of the system is the refinement stage. The refinement process consists out of data refinement, operation refinement, and operation decomposition. In this dissertation, Z, Object-Z and UML (Unified Modelling Language) are used as specification languages and C, C++, Cobol and Object-Oriented Cobol are used as implementation languages. As an illustration a small system, The ITEM System, is specified in Z and UML and implemented in Object-Oriented Cobol.ComputingM. Sc. (Information Systems
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