2,377 research outputs found
Process algebra with guards : combining Hoare logic with process algebra (Extended abstract)
No full textProcess algebra with guards : combining Hoare logic with process algebra (Extended abstract)
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Focus points and convergent process operators: a proof strategy for protocol verification
No full textAbstractWe present a method for efficiently providing algebraic correctness proofs for communication systems. It is described in the setting of μCRL [J.F. Groote, A. Ponse, The syntax and semantics of μCRL, in: A. Ponse, C. Verhoef, S.F.M. van Vlijmen (Eds.), Algebra of Communicating Processes, Workshops in Computing, Springer, Berlin, 1994, pp. 26–62] which is, roughly, ACP [J.C.M. Baeten, W.P. Weijland, Process Algebra, Cambridge Tracts in Theoretical Computer Science, vol. 18, Cambridge University Press, Cambridge 1990, J.A. Bergstra, J.W. Klop, The algebra of recursively defined processes and the algebra of regular processes, in: Proceedings of the 11th ICALP, Antwerp, Lecture Notes in Computer Science, vol. 172, Springer, Berlin, 1984, pp. 82–95] extended with a formal treatment of the interaction between data and processes. The method incorporates assertional methods, such as invariants and simulations, in an algebraic framework, and centers around the idea that the state spaces of distributed systems are structured as a number of cones with focus points. As a result, it reduces a large part of algebraic protocol verification to the checking of a number of elementary facts concerning data parameters occurring in implementation and specification. The resulting method has been applied to various non-trivial case studies of which a number have been verified mechanically with the theorem checker PVS. In this paper the strategy is illustrated by several small examples and one larger example, the Concurrent Alternating Bit Protocol (CABP)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Focus points and convergent process operators
Full text linkWe present a strategy for finding algebraic correctness proofs for communication systems. It is described in the setting of CRL (Groote and Ponse 93) which is, roughly, ACP (Baeten and Weijland 90, Bergstra and Klop 84) extended with a formal treatment of the interaction between data and processes. The strategy has already been applied successfully in non-trivial case studies (e.g., Bezem and Groote 94, and Fredlund, Groote, and Korver 95), but was not explicitly identified as such. Moreover, the protocols that were verified in these papers were rather complex, so that the general picture was obscured by the amount of details. In this paper, the proof strategy is materialised in the form of definitions and theorems. These results reduce a large part of protocol verification to a number of trivial facts concerning data parameters occurring in implementation and specification. This greatly simplifies protocol verifications and makes our approach amenable to mechanical assistance; experiments in this direction seem promising. The strategy is illustrated by several small examples and one larger example, the Concurrent Alternating Bit Protocol (CABP). Although simple, this protocol contains a large amount of internal parallelism, so that all relevant issues make their appearance
Fabrieksschema betreffende de "Bereiding van Magnesium uit Zeewater": Deel I
No full textDocument(en) uit de collectie Chemische Procestechnologie Deel II zie: Deeg, J.F., Chemical Process Design 1101DelftChemTechApplied Science
Investigating the effects of designing industrial control software using push and poll strategies
No full textIn this paper we apply a number of design guidelines for circumventing the state space explosion problem from [J.F. Groote, T.W.D.M. Kouters, and A.A.H. Osaiweran, Specification guidelines to avoid the state space explosion problem, 2011] to the design and formal verification of a real industrial case, namely a controller of a power distribution unit of X-ray machines developed at Philips Healthcare. Through this work we investigate whether these guidelines are effective in designing practical applications. We provide a number of alternative designs that mainly incorporate pushing and polling strategies, taking into account a number of these guidelines. Using the pushing strategy components notify one another when information becomes available while using polling components ask for information only when it is needed. We find that designs that use a pushing strategy and do not apply such guide-lines typically lead to the generation of substantially more states. All demonstrated designs formally refine a single predefined external specification that captures the desired external behavior of the system. Moreover, all designs are deadlock free and do not exhibit any illegal interactions. This confirms our hypothesis that the design guidelines are really effective in practical contexts
The parallel composition of uniform processes with data
Full text linkAbstractA general basis for the definition of a finite but unbounded number of parallel processes is the equation S(n,dt)=P(0,get(0,dt))◁eq(n,0)▷(P(n,get(n,dt))∥S(n−1,dt)). In this formula eq(n,0) is an equality test, and get(n,dt) denotes the nth data element in table dt. We derive a linear process equation with the same behaviour as S(n,dt), and show that this equation is well-defined, provided one adopts the principle CL-RSP from Bezem and Groote (Proceedings of Concur’94, Springer, Berlin, 1994, pp. 401–416). In order to demonstrate the strength of our result, we use it for the analysis of a standard example. We show that n+1 concatenated buffers form a queue of capacity n+1
Beatty, J.F., and the Law of Manslaughter
Full text linkIn this article, the author argues that the recent Supreme Court of Canada decisions in R. v. Beatty and R. v. J.F. have clarified several of the issues that have plagued the increasingly complicated offence of manslaughter. In particular, the decisions address the redundancy among the many manslaughter provisions in the Criminal Code, the need to define a clear separation between actus reus and mens rea, and the need to establish distinct categories of objective fault for different types of manslaughter offences. The author examines the legal background of these decisions as well as the current state of the law. He concludes by identifying emerging issues relating to the offence of manslaughter, arguing that the law remains convoluted and in need of urgent reform despite the progress made in the Beatty and J.F. decisions
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