2010 Working Papers
Permanent URI for this collection
Recent Submissions
Item History navigation in location-based mobile systems(Working Paper, University of Waikato, Department of Computer Science, 2010-12-01) Müller, Knut; Hinze, AnnikaThe aim of this paper is to provide an overview and comparison of concepts that have been proposed to guide users through interaction histories (e.g. for web browsers). The goal is to gain insights into history design that may be used for designing an interaction history for the location-based Tourist Information Provider (TIP) system [8]. The TIP system consists of several services that interact on a mobile device.Item Datalog as a parallel general purpose programming language(Working Paper, University of Waikato, Department of Computer Science, 2010-08-27) Cleary, John G.; Utting, Mark; Clayton, RogerThe increasing available parallelism of computers demands new programming languages that make parallel programming dramatically easier and less error prone. It is proposed that datalog with negation and timestamps is a suitable basis for a general purpose programming language for sequential, parallel and distributed computers. This paper develops a fully incremental bottom-up interpreter for datalog that supports a wide range of execution strategies, with trade-offs affecting efficiency, parallelism and control of resource usage. Examples show how the language can accept real-time external inputs and outputs, and mimic assignment, all without departing from its pure logical semantics.Item The language of certain conflicts of a nondeterministic process(Journal Article, University of Waikato, Department of Computer Science, 2010-07-07) Malik, RobiThe language of certain conflicts is the most general set of behaviours of a nondeterministic process, which certainly lead to a livelock or deadlock when accepted by another process running in parallel. It is of great use in model checking to detect livelocks or deadlocks in very large systems, and in process-algebra to obtain abstractions preserving livelock and deadlock. Unfortunately, the language of certain conflicts is difficult to compute and has only been approximated in previous work. This paper presents an effective algorithm to calculate the language of certain conflicts for any given nondeterministic finite-state process and discusses its properties. The algorithm is shown to be correct and of exponential complexity.Item Random model trees: an effective and scalable regression method(Working Paper, University of Waikato, Department of Computer Science, 2010-06) Pfahringer, BernhardWe present and investigate ensembles of randomized model trees as a novel regression method. Such ensembles combine the scalability of tree-based methods with predictive performance rivaling the state of the art in numeric prediction. An extensive empirical investigation shows that Random Model Trees produce predictive performance which is competitive with state-of-the-art methods like Gaussian Processes Regression or Additive Groves of Regression Trees. The training and optimization of Random Model Trees scales better than Gaussian Processes Regression to larger datasets, and enjoys a constant advantage over Additive Groves of the order of one to two orders of magnitude.Item Implementing an event-driven service-oriented architecture in TIP(Working Paper, University of Waikato, Department of Computer Science, 2010-06-17) Rinck, Michael; Hinze, AnnikaMany mobile devices have a density of services, many of which are context or location-aware. To function, many of these services have to collaborate with other services, which may be located in many different places and networks. There is often more then on service suitable for the task at hand. To decide which service to use, quality of service measurements like the accuracy or reliability of a service need to be known. Users do not want third parties to have statistics on how and where they used services. Therefore the collaboration needs to be anonymous. This project implements a model of event-based context-aware service collaboration on a publish/subscribe basis. We compare different implementation designs, with focus on anonymity and quality of service of the services.