@workingpaper{

   Author = {Bittner, S. and Hinze, A.},

   Title = {Arbitrary Boolean advertisements: the final step in supporting the Boolean publish/subscribe model},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {06/2006},

   Pages = {1-46},

   Month = {June},

   Abstract = {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.},

   URL = {http://www.cs.waikato.ac.nz/pubs/wp/2006/uow-cs-wp-2006-06.pdf},

   Year = {2006} }
   

   
@workingpaper{

   Author = {Bittner, S. and Hinze, A.},

   Title = {Event distributions in online book auctions},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {03/2006},

   Pages = {1-23},

   Month = {February},

   Abstract = {Current quantitative evaluations in various research areas for publish/subscribe systems use artificially created event messages to model the system workload. The assumptions made to create these workloads are rather strong and hardly ever described in detail. This does not allow for a repetition of experiments or comparative evaluations of different approaches by different researches.
   
   In this paper, we present an evaluation of the distributions of the values of attributes typically used in online auction scenarios. In particular, we focus on auctions of fiction books. We further show our approach of creating event messages by the help of the gained information. Publishing this information on how to create a typical workload for online auctions should allow for the repetition of experiments and the comparison of different evaluations.},

   URL = {http://www.cs.waikato.ac.nz/pubs/wp/2006/uow-cs-wp-2006-03.pdf},

   Year = {2006} }
   
   
@workingpaper{

   Author = {Bittner, S. and Hinze, A.},

   Title = {Subscription tree pruning: a structure-independent routing optimization for general-purpose publish/subscribe systems},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {01/2006},

   Pages = {1-31},

   Month = {January},

   Abstract = {A main challenge in distributed publish/subscribe systems is the efficient and scalable routing of incoming information (event messages). For large-scale publish/subscribe services, subscription forwarding has been established as a prevalent routing scheme. It reduces the network traffic for event routing due to selectively forwarding event messages to relevant parts of the network only. To further improve event routing, publish/subscribe systems apply routing optimizations. So far, optimizations for general-purpose publish/subscribe systems are still missing.
   
   In this paper, we present the architecture, realization, and evaluation of our prototype of a large-scale publish/subscribe service applying a novel routing optimization, subscription tree pruning. We also show a comparison of five existing routing optimizations in respect to six important characteristic parameters affecting the suitability of these approaches in practice (including space usage, time efficiency (throughput), and network load). This comparative analysis clearly demonstrates the advantages of subscription pruning over other routing optimizations. In our practical experiments, we then investigate the behavior of our prototype regarding all quantitatively measurable parameters from our previously theoretically analyzed ones. Our evaluation of subscription pruning in this paper is more extensive than previous analyses of any routing optimizations for publish/subscribe systems, which focus on selected parameters only.},

   URL = {http://www.cs.waikato.ac.nz/pubs/wp/2006/uow-cs-wp-2006-01.pdf},

   Year = {2006} }


   
@workingpaper{

   Author = {Hall, M.},

   Title = {A decision tree-based attribute weighting filter for Naive Bayes},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {05/2006},

   Pages = {1-12},

   Month = {May},

   Abstract = {The naive Bayes classifier continues to be a popular learning algorithm for data mining applications due to its simplicity and linear run-time. Many enhancements to the basic algorithm have been proposed to help mitigate its primary weakness?the assumption that attributes are independent given the class. All of them improve the performance of naive Bayes at the expense (to a greater or lesser degree) of execution time and/or simplicity of the fina lmodel. In this paper we present a simple filter method for setting attribute weights for use with naive Bayes. Experimental results show that naive Bayes with attribute weights rarely degrades the quality of the model compared to standard naive Bayes and, in many cases, improves it dramatically. The main advantages of this method compared to other approaches for improving naive Bayes is its run-time complexity and the fact that it maintains the simplicity of the final model.},

   URL = {http://www.cs.waikato.ac.nz/pubs/wp/2006/uow-cs-wp-2006-05.pdf},

   Year = {2006} }







@workingpaper{

   Author = {Hinze, A. and Jung, D. and Cunningham, S.J.},

   Title = {Proceedings of the Second Computing Women Congress (CWC 2006): Student Papers, Hamilton, New Zealand, 11-19 February 2006},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {02/2006},

   Pages = {1-32},

   Month = {February},

   Abstract = {The Second Computing Women Congress was held at the University of Waikato, Hamilton, New Zealand from February 11th to 19th, 2006.  The Computing Women Congress (CWC) is a Summer University of women in computer science.  It is a meeting-place for female students, academics and professionals who study or work in Information Technology.  CWC provides a forum to learn about and share the latest ideas of computing related topics in a supportive environment.  CWC provides an open, explorative learning and teaching environment.  Experimentation with new styles of learning is encouraged, with an emphasis on hands-on experience and engaging participatory techniques.},

      Year = {2006} }







@workingpaper{

   Author = {Reeves, S. and Streader, D.},

   Title = {Liberalising Event B without changing it},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {07/2006},

   Pages = {1-13},

   Month = {July},

   Abstract = {We transfer a process algebraic notion of refinement to the B method by using the well-known bridge between the relational semantics underlying the B machines and the labelled transition system semantics of processes. Thus we define delta refinement on Event B systems. We then apply this new refinement to a problem from the literature that previously could only be solved by retrenchment.},

   Keywords = {process refinement, automatic verification, frame refinement, Event B},

   URL = {http://www.cs.waikato.ac.nz/pubs/wp/2006/uow-cs-wp-2006-07.pdf},

   Year = {2006} }







@workingpaper{

   Author = {Reeves, S. and Streader, D.},

   Title = {LSB - Live and Safe B alternative semantics for Event B},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {08/2006},

   Pages = {1-18},

   Month = {July},

   Abstract = {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.},

   Keywords = {Process refinement, Event B, Live B, Safe B, LSB},

   URL = {http://www.cs.waikato.ac.nz/pubs/wp/2006/uow-cs-wp-2006-08.pdf},

   Year = {2006} }







@workingpaper{

   Author = {Reeves, S. and Streader, D.},

   Title = {State- and Event-based refinement},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {09/2006},

   Pages = {1-8},

   Month = {September},

   Abstract = {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.},

   Keywords = {Data refinement, process refinement, singleton failures},

   URL = {http://www.cs.waikato.ac.nz/pubs/wp/2006/uow-cs-wp-2006-09.pdf},

   Year = {2006} }







@workingpaper{

   Author = {Twidale, M.B. and Nichols, D.M.},

   Title = {Computational sense: the role of technology in the education of digital librarians},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {10/2006},

   Pages = {1-8},

   Month = {October},

   Abstract = {The rapid progress of digital library technology from research to implementation has created a force for change in the curricula of library schools. The education of future librarians has always had to adapt to new technologies but the pace, complexity and implications of digital libraries pose considerable challenges. In this article we explore how we might successfully blend elements of computer science and library science to produce effective educational experiences for the digital librarians of tomorrow. We first outline the background to current digital librarian education and then propose the concept of computational sense as an appropriate meeting point for these two disciplines.},

      URL = {http://www.cs.waikato.ac.nz/pubs/wp/2006/uow-cs-wp-2006-10.pdf},

   Year = {2006} }







@workingpaper{

   Author = {Utting, M. and Pretschner, A. and Legeard, B.},

   Title = {A taxonomy of model-based testing},

   Publisher = {Department of Computer Science, The University of Waikato},

   Number = {04/2006},

   Pages = {1-18},

   Month = {April},

   Abstract = {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.},

      URL = {http://www.cs.waikato.ac.nz/pubs/wp/2006/uow-cs-wp-2006-04.pdf},

   Year = {2006} }







      







      