Computer Science Technical Reports (1987+)
Permanent URI for this collectionhttps://hdl.handle.net/2292/3452
Computer Science Department
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Item Logic Blog 2012(University of Auckland Computer Science Department, 2012) Nies, AndreThe 2012 logic blog has focussed on the following: Randomness and computable analysis/ergodic theory; Systematizing algorithmic randomness notions; Traceability; Higher randomness; Calibrating the complexity of equivalence relations from computability theory and algebra.Item Logic Blog 2011(2011) Nies, AndreItem Measuring IPv4-IPv6 translation techniques(University of Auckland Computer Science Department, 2012) Yu, Young; Carpenter, BrianThis document reviews currently proposed IPv4-IPv6 translation techniques and describes a simple performance study of three open-source IPv4-IPv6 translators. The purpose of this document is to introduce the fundamental ideas behind NAT-PT, NAT64 and HTTP proxy and to measure the performance effect on round-trip time of using these translators in a simple network with up to 100 simultaneous connections.Item Comparing Hash Function Algorithms for the IPv6 Flow Label(University of Auckland Computer Science Department, 2012) Anderson, Lewis; Brownlee, John; Carpenter, BrianWe compare several stateless hash algorithms for generating IPv6 flow labels, by testing them against trace files of IPv6 traffic measured at four different sites. The criteria for comparison were uniformity of the resulting distribution of hash values and computing time. Of the algorithms tested, we recommend FNV1a-32. We also note how the hash values may be made hard for a third party to predict.Item Deviations from Power Law in Citation Distributions(University of Auckland Computer Science Department, 2010) Barker, Richard; Carpenter, Brian; Tempero, EwanIt is commonly asserted that citations within a corpus of material such as scholarly articles or web pages show a power law distribution. While this appears to be approximately true for incoming citations, we describe cases where there is substantial deviation from a power law for outgoing citations.Item Observations of UDP to TCP Ratio and Port Numbers(University of Auckland Computer Science Department, 2009) Lee, DongJin; Carpenter, Brian; Brownlee, NevilWidely used protocols (UDP and TCP) are observed for variations of the UDP to TCP ratio and of port number distribution, both over time and between different networks. The purpose of the study was to understand the impact of application trends, especially the growth in media streaming, on traffic characteristics. The results showed substantial variability but little sign of a systematic trend over time, and only wide spreads of port number usage.Item Logic Blog 2010(University of Auckland Computer Science Department, 2010) Nies, Andre; Bienvenu; KhalimulinItem Rewriting History: More Power to Creative People(University of Auckland Computer Science Department, 2011) Lutteroth, Christof; Weber, GeraldTrying out different alternatives is a natural part of creative work. However, with the current tools we often end up having to redo changes that worked in one alternative on other versions. This is additional work that should be unnecessary in our electronic age. We propose a new approach for supporting creative work: an artifact is described as the history of the operations that created it. We show that by allowing users to change the history, the common use cases of merging, generalizing and specializing can be supported efficiently. The “rewriting history” approach is based on a formal specification of the operations offered by a tool, and enables exciting new ways to share and combine creative work. It is complementary to state-based version control and offers the user a new understanding of merging. It was implemented for a drawing tool that supports synchronous collaborative work.Item Tuple Space for Mashups(University of Auckland Computer Science Department, 2011) Lutteroth, Christof; Tian, Sheng; Weber, GeraldInter-widget communication is essential for enterprise mashup applications. To implement it, current mashups use the publish/subscribe pattern. However, for mashup scenarios with many interactions between widgets, this pattern requires a lot of manual wiring between the widgets in existing mashup platforms. In this paper, we propose a new event model, UWEM, which is an extension of Linda and Tuple Space. UWEM separates event publishers and subscribers in space, time and reference. It provides a more flexible and effective interaction pattern among widgets. It makes it easier for users to build mashups, and also delivers a plug and play experience of building mashup application for users. We have implemented UWEM in a popular enterprise mashup framework.Item The Feasibility and Use of a Minor Containment Algorithm(Department of Computer Science, The University of Auckland, New Zealand, 2000-02) Xiong, Liu; Dinneen, MichaelWe present a general algorithm for checking whether one graph is a minor of another. Although this algorithm is not polynomial-time, it is quite practical for small graphs. For all connected graphs with 5 vertices or less we count how many connected graphs of order at most 9 are above them in the minor order. Our computed tables may be useful in the design of heuristic algorithms for minor closed families of graphs.Item Watermarking, Tamper-Proofing, and Obfuscation -- Tools for Software Protection(Department of Computer Science, The University of Auckland, New Zealand, 2000-02) Collberg, Christian; Thomborson, C.We identify three types of attack on the intellectual property contained in software, and three corresponding technical defences. A potent defense against reverse engineering is obfuscation, a process that renders software unintelligible but still functional. A defense against software piracy is watermarking, a process that makes it possible to determine the origin of software. A defense against tampering is tamper-proofing, so that unauthorized modifications to software (for example to remove a watermark) will result in non-functional code. We briefly survey the available technology for each type of defense.Item Artificial Intelligence -- or not ?(Department of Computer Science, The University of Auckland, New Zealand, 1999-12) Creak, G.A.[no abstract available]Item Image Flow in Light Fields(Department of Computer Science, The University of Auckland, New Zealand, 1999-08) van der Linden, JarnoImage-based modeling can simplify the scene modeling process in computer graphics by assuming that it is not the geometry of a scene that is of interest, but rather the look of a scene. Instead of obtaining detailed surface geometry and colour data, visual data alone is acquired. This can be done with relative ease through photography. Light Fields are a recent development in how such information is stored. Images of a scene are used to create a four dimensional radiance function. A light field determines what a scene looks like when viewed from anywhere outside of the space enclosing the scene. With light fields, as in many other image-based modeling and rendering systems, there is a trade-off between quality and memory. A high quality result requires storage of a large number of samples obtained from high-resolution input images. The number of images required can be reduced by using image warping techniques based on image flow. Image warping computes intermediate images from the existing images in the system, thereby giving the illusion of a higher sampling density than that actually used during acquisition. In this paper, we show how to use image flow in light fields to produce high quality output from only a small set of input images. Unlike previous work, we do not generate intermediate images, but rather use image flow to render a new view directly. High quality new views can be generated from as few as 8x8 images. We demonstrate several rendering methods for image-flow augmented light fieldsItem User Friendly Interface for Maintaining BibTeX Databases(Department of Computer Science, The University of Auckland, New Zealand, 1999-06) Kim, See Mu; Dinneen, MichaelWe describe a new bibliographic database tool, BIBTECKER, that helps users manage their BIBTEX databases. The main features of BIBTECKER are a GUI interface, a built-in entry syntax checker, user extendable type fields, comment maintenance, verbose mode and command line parameters. We also compare BIBTECKER with existing BIBTEX tools and mention plausible improvements.Item AI is Dead: Long Live AI(Department of Computer Science, The University of Auckland, New Zealand, 1999-03) Qualtrough, P.The time seems ripe to reflect on the state of AI and re-evaluate its goals and techniques. It is argued that a fundamental oversight has been made in adopting a focus on knowledge and reasoning without simultaneously emphasising understanding and meaning. Despite not being able to define the latter term precisely, we can exploit our limited knowledge of meaning that most AI efforts will simply never achieve artificial intelligence of the kind that many pioneers in the field envisaged, or that most members of the public imagine when they hear this term. The only route to this goal is argued to be via learning, and objections to this approach are argued to be weak or flawed. A number of implications of learning with the specific aim of acquiring meaning and understanding capabilities are discussed.Item A Simple but Effective Web-Based Report Server(Department of Computer Science, The University of Auckland, New Zealand, 1999-03) Xiong, Liu; Dinneen, MichaelWe present a practical web-based server that supports several views (entries sorted by author, title and serial number) of a collection of research reports. A powerful search feature, which exploits Perl regular expressions, is incorporated in the server. Although designed for the Centre for Discrete Mathematics and Theoretical Computer Science (Auckland, New Zealand), this simple presentation tool can be easily installed to disseminate electronic copies of technical reports for other institutions. By design, no HTML programming experience is necessary for adding new reports to the server (or browser interface).Item On the Limits of Software Watermarking(Department of Computer Science, The University of Auckland, New Zealand, 1998-07) Collberg, Christian; Thomborson, C.Watermarking embeds a secret message into a cover message. In media watermarking the secret is usually a copyright notice and the cover a digital image. Watermarking an object discourages intellectual property theft, or when such theft has occurred, allows us to prove ownership. The Software Watermarking problem can be described as follows. Embed a structure W into a program P such that: W can be reliably located and extracted from P even after P has been subjected to semantic preserving transformations such as code optimization and obfuscation; W is stealthy; W has a high data rate; embedding W into P does not adversely affect the performance of P; and W has a mathematical property that allows us to argue that its presence in P is the result of deliberated actions. In the first part of the paper we construct an informal taxonomy of software watermarking techniques. In the second part we formalize these results. Finally, we propose a new software watermarking technique in which a dynamic graphic watermark is stored in the execution state of a program.Item STEbus-based Hardware for a Model Railway Control System(Department of Computer Science, The University of Auckland, New Zealand, 1998-04) Qualtrough, P.This report describes STEbus-based hardware that has been acquired and constructed to provide the basis for a system to control a model railway. The equipment in use may be divided into three basic functional areas: the model railway equipment itself, a computing facility, and special purpose STEbus boards which transform the low power digital logic of the computer(s) into the higher powered analogue signals which drive the train motors (i.e. interfacing circuitry between the other two system components). This main purpose of this report is to document the two types of board which make up the interfacing circuitry, both of which were locally designed and produced. In order to understand fully the design and operation of these boards, the nature of the other parts of the system will first be described.Item A New Structure for an Operating Systems Course(Department of Computer Science, The University of Auckland, New Zealand, 1998-03) Creak, G.A.; Sheehan, RobertThis report has grown from a seminar which we presented to the Auckland University Computer Science Department in 1995. Though blandly entitled "An Operating Systems Course", it was in fact an account of changes which we had made in the nature of the department's final undergraduate year operating systems course since Alan took charge of it in 1985. Robert joined in 1988 while Alan was on leave; since 1989, we have presented the course jointly except during Alan's further leave in 1996. -- from Introduction.Item Departmental Songbook (v1.3 $\beta$)(Department of Computer Science, The University of Auckland, New Zealand, 1997-11) Collberg, Christian[no abstract available]