1,721,013 research outputs found
Section 3.8 written by Divakar Yadav and Michael Butler
No full textOne aim of the Rodin project is to contribute formal methods which will underpin the creation of fault-tolerant systems. This intermediate report from WP2 (Methodology) describes progress during the second year of the Rodin project; it also discusses our plans for the final deliverable on methodology. Contributors: Many people have written material for Chapters 3 and 2; specific contributions include: Section 2.1 written by Linas Laibinis Section 2.2 written by Ian Johnson Section 2.3 written by Ian Oliver Section 2.4 written by Neil Evans and Michael Butler (on behalf of Praxis) Section 2.5 written by Maciej Koutny Section 3.1 written by Maciej Koutn
The Re-entrance Problem and Its Solution
No full textIn this paper we take a formal look at the nature of the re-entrance problem. We see the essence of the problem in a conflict between the assumptions components make about each other's behavior. We argue that to ensure safe composability of mutually dependent components in an open system one needs to reason about them modularly. We propose an approach for extending component specifications with rely/guarantee conditions, explicitly expressing the assumptions components can safely make about each other. Accordingly, we define how to refine components in accordance with the rely/guarantee conditions. By extending the refinement calculus, we define a customized theory of components necessary for reasoning about composability. Then we formally prove that refining components taking into account the rely/guarantee conditions permits to reason about component systems modularly and in this way avoid the re-entrance problem. Keywords : re-entrance problem, modular reasoning, component substitut..
Fault Tolerance in Use-Case Modeling
No full textFault tolerance – an ability of a system to cope with errors – is an important characteristic of safety-critical systems. However, the current approaches to software development often ignore the fault tolerance aspect. This results in an ad-hoc and often incorrect introduction of the fault tolerance mechanisms into system design. In this paper, we summarize the experience gained in the formal development of a highly-reliable industrial robot and propose an approach which allows us to systematically capture requirements describing the fault tolerance mechanisms in use-case modeling. An application of our approach supports integrating fault tolerance consideration into the entire software development process. 1
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
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