2006 Working Papers

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Now showing 1 - 5 of 10
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    Proceedings of the second computing women congress: Student Papers
    (Working Paper, University of Waikato, Department of Computer Science, 2006-02-11) Hinze, Annika; Jung, Doris; Cunningham, Sally Jo
    The CWC 2006 Proceedings contains the following student papers: • Kathryn Hempstalk: Hiding Behind Corners: Using Edges in Images for Better Steganography • Supawan Prompramote, Kathy Blashki: Playing to Learn: Enhancing Educational Opportunities using Games Technology • Judy Bowen: Celebrity Death Match: Formal Methods vs. User-Centred Design • Liz Bryce: BECOMING INDIGENOUS: an impossible necessity • Tatiana King: Privacy Issues in Health Care and Security of Statistical Databases • Nilufar Baghaei: A Collaborative Constraint-based Intelligent System for Learning Object-Oriented Analysis and Design using UML • Sonja van Kerkhof: Alternatives to stereotypes: some thoughts on issues and an outline of one game
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    Arbitrary boolean advertisements: the final step in supporting the boolean publish/subscribe model
    (Working Paper, Department of Computer Science, University of Waikato, 2006-06-01) Bittner, Sven; Hinze, Annika
    Publish/subscribe systems allow for an efficient filtering of incoming information. This filtering is based on the specifications of subscriber interests, which are registered with the system as subscriptions. Publishers conversely specify advertisements, describing the messages they will send later on. What is missing so far is the support of arbitrary Boolean advertisements in publish/subscribe systems. Introducing the opportunity to specify these richer Boolean advertisements increases the accuracy of publishers to state their future messages compared to currently supported conjunctive advertisements. Thus, the amount of subscriptions forwarded in the network is reduced. Additionally, the system can more time efficiently decide whether a subscription needs to be forwarded and more space efficiently store and index advertisements. In this paper, we introduce a publish/subscribe system that supports arbitrary Boolean advertisements and, symmetrically, arbitrary Boolean subscriptions. We show the advantages of supporting arbitrary Boolean advertisements and present an algorithm to calculate the practically required overlapping relationship among subscriptions and advertisements. Additionally, we develop the first optimization approach for arbitrary Boolean advertisements, advertisement pruning. Advertisement pruning is tailored to optimize advertisements, which is a strong contrast to current optimizations for conjunctive advertisements. These recent proposals mainly apply subscription-based optimization ideas, which is leading to the same disadvantages. In the second part of this paper, our evaluation of practical experiments, we analyze the efficiency properties of our approach to determine the overlapping relationship. We also compare conjunctive solutions for the overlapping problem to our calculation algorithm to show its benefits. Finally, we present a detailed evaluation of the optimization potential of advertisement pruning. This includes the analysis of the effects of additionally optimizing subscriptions on the advertisement pruning optimization.
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    LSB - Live and Safe B: Alternative semantics for Event B
    (Working Paper, Department of Computer Science, University of Waikato, 2006-07-01) Reeves, Steve; Streader, David
    We define two lifted, total relation semantics for Event B machines: Safe B for safety-only properties and Live B for liveness properties. The usual Event B proof obligations, Safe, are sufficient to establish Safe B refinement. Satisfying Safe plus a simple additional proof obligation ACT REF is sufficient to establish Live B refinement. The use of lifted, total relations both prevents the ambiguity of the unlifted relational semantics and prevents operations being clairvoyant.
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    State- and event-based refinement
    (Working Paper, Department of Computer Science, University of Waikato, 2006-09-01) Reeves, Steve; Streader, David
    In this paper we give simple example abstract data types, with atomic operations, that are related by data refinement under a definition used widely in the literature, but these abstract data types are not related by singleton failure refinement. This contradicts results found in the literature. Further we show that a common way to change a model of atomic operations to one of value passing operations actually changes the underlying atomic operational semantics.
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    A Taxonomy of model-based testing
    (Working Paper, Department of Computer Science, University of Waikato, 2006-04-01) Utting, Mark; Pretschner, Alexander; Legeard, Bruno
    Model-based testing relies on models of a system under test and/or its environment to derive test cases for the system. This paper provides an overview of the field. Seven different dimensions define a taxonomy that allows the characterization of different approaches to model-based testing. It is intended to help with understanding benefits and limitations of model-based testing, understanding the approach used in a particular model-based testing tool, and understanding the issues involved in integrating model-based testing into a software development process. To illustrate the taxonomy, we classify several approaches embedded in existing model-based testing tools.