Digital Commons Network^™

Formal Tools For Managing Inconsistency And Change In Re, Aditya K. Ghose

Faculty of Informatics - Papers (Archive)

Dealing with inconsistencies and change in requirements engineering (RE) is known to be a difficult problem. We propose a formal, integrated approach to inconsistency handling and requirements evolution with a focus on providing automated support. We define a novel representation scheme that is expressive and able to maintain several key semantic distinctions. Based on this scheme, we define a toolkit of inconsistency handling technique. We define a principled process for evolving such specifications, with minimal computational cost and user intervention. Finally, we describe the REFORM system which implements some of these techniques.

Query Scrambling In Distributed Multidatabase Systems, J. R. Getta

Faculty of Informatics - Papers (Archive)

This work addresses the problem of efficient query processing in multidatabase systems distributed over wide-area networks. The solution unifies the query scrambling and reduction approaches to dynamic optimization of query processing plans at the data integration stage. The paper presents a new data integration algorithm based on query scrambling and the extended reduction technique. The algorithm both reschedules data integration operations and reductions of arguments and permits the concurrent computations of operations and reductions.

Construction Of Cubic Homogeneous Boolean Bent Functions, Jennifer Seberry, Tianbing Xia, J. Pieprzyk

Faculty of Informatics - Papers (Archive)

We prove that cubic homogeneous bent functions f : V2n → GF(2) exist for all n ≥ 3 except for n = 4.

On The Spectrum Of An F-Square, L. Fitina, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Given an F-square of some type F(n; αo, αl, ..., αv-1) what critical set sizes can we obtain for this type? Such a question was considered by Donovan and Howse (1999), in the case of Latin squares. In this note we solve this question for the type F(n;1,n – 1), and also obtain partial results for type F(n; 2,n – 2).

Normal Numbers Without Measure Theory, R. Nillsen

Faculty of Informatics - Papers (Archive)

Any number can be expanded to the base 10, leading to a sequence of digits between 0 and 9 corresponding to the number. Also, any number can be expanded to the base 2, leading to a sequence of digits, each one being either 0 or 1, corresponding to the number. It is result due to Émile Borel in 1904 that “almost all” numbers have the property that, when expanded to the base 2, each of the digits 0 and 1 appears with an asymptotic frequency of 1/2. That is, if we regard the sequence of digits in the expansion to …

Memory Truncation Receivers For Transmultiplexers, Alfred Mertins

Faculty of Informatics - Papers (Archive)

In this paper, the design of optimal receive filter banks for transmultiplexer-based data transmission over frequency selective channels is investigated. A new design strategy based on the principle of memory truncation, rather than equalization, is presented. Through the receive filters, each subchannel is truncated to a certain length, and the actual data detection is then carried out via low-complexity, independently operating Viterbi detectors. Design examples are presented for high-speed transmission over copper wires. The examples show that memory truncation allows significant performance improvements over MMSE equalization.

Accurate, Critically Sampled Characteristic Waveform Surface Construction For Waveform Interpolation Decomposition, N. R. Chong-White, I. Burnett

Faculty of Informatics - Papers (Archive)

A waveform-matched waveform interpolation (WMWI) technique is presented which offers improved signal analysis over standard WI coders and, in the unquantised case, perfect reconstruction. In WMWI, an accurate representation of speech evolution is formed by extracting consecutive pitch periods of a time-warped, constant pitch residual. A pitch track optimisation technique is described which ensures that the critically sampled pitch periods can be effectively decomposed into a slowly evolving and rapidly evolving waveform, allowing efficient quantisation.

Multiparty Key Agreement Protocols, J. Pieprzyk, C. H. Li

Faculty of Informatics - Papers (Archive)

A class of multiparty key agreement protocols based on secret sharing is presented. The trust infrastructure necessary to achieve the intended security goals is discussed.

Differentiated Service Performance Analysis, L. V. Nguyen, A. Eyers, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

Differentiated service (DiffServ) has been proposed as an alternative for Integrated service. It aims to provide the same service to a group of flows that have similar quality of service requirements. Assured forwarding (AF) and expedited forwarding (EF) are two proposals for DiffServ provision. We present a performance analysis of an N drop-precedences threshold dropping (TD) queue, which is one of the proposed mechanisms for AF. In this analysis, traffic flows are assumed Poisson with exponentially distributed service time. We present simulation results that verify the analysis. This paper is an extension of the work attempted by Bolot et al. …

Connection Admission Control In Micro-Cellular Multi-Service Mobile Networks, R. S. Raad, E. Dutkiewicz, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

This paper investigates the use of fixed bandwidth reservation for multi-service mobile networks. In particular it extends previous fixed multi-service network results to the mobile scenario and presents analytical and simulation results for new and handover call blocking probabilities. It also investigates the performance sensitivity to different traffic load ratios as well as the cell dwell time distribution.

666 Or 616 (Rev. 13,18), M. G. Michael

Faculty of Informatics - Papers (Archive)

No abstract provided.

Ip Forwarding Alternatives In Cell Switched Optical Networks, P. Boustead, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

Optical switching will enable core Internet packet switching to scale with future transmission rate increases. Currently proposed optical ATM switches do not allow packet reassembly, which is necessary for packet level forwarding. This results in the requirement to create end to end ATM virtual connections for flows even if they contain only one packet. In electronically switched networks MPOA and MPLS allow both cell and packet level forwarding to overcome this problem. This paper examines the feasibility of implementing such protocols over an optically switched network. Two different architectures are examined: use of an adjunct electrical router; and native optical …

Linear Prediction Incorporating Simultaneous Masking, J Lukasiak, I. S. Burnett, Joe F. Chicharo, M. M. Thomson

Faculty of Informatics - Papers (Archive)

Whilst linear prediction is the cornerstone of most modern speech coders, few of these coders incorporate the perceptual characteristics of hearing into the calculation of the linear predictor coefficients (LPCs). This paper proposes a method of incorporating simultaneous masking into the calculation of the LPCs. This modification requires only a modest increase in computational complexity and results in the linear predictor removing more perceptually important information from the input speech signal. This results in a filter that better models the formants of the input speech spectrum. The net effect is that an improvement in quality is achieved for a given …

The Second International Symposium On Constructing Software Engineering Tools (Coset2000), J. Gray, L. Scott, I. Ferguson

Faculty of Informatics - Papers (Archive)

No abstract provided.

Computing Running Dcts And Dsts Based On Their Second-Order Shift Properties, Jiangtao Xi, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

This paper presents a set of second-order recursive equations which are referred to as the second-order shift (SOS) properties of the discrete cosine transform (DCT) and the discrete sine transform (DST). The proposed SOS properties enable independent updating of the respective DCT and DST coefficients. This is in direct contrast with existing methodology for computing the running DCT and DST where there is an inherent interdependency between the DCT and DST coefficients. The SOS properties provide more efficient algorithms in terms of computational burden and memory requirements when implementing running DCTs and DSTs.

A New Waveform Interpolation Coding Scheme Based On Pitch Synchronous Wavelet Transform Decomposition, N. R. Chong, I. Burnett, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

This correspondence uses a pitch synchronous wavelet transform (PSWT) as an alternative characteristic waveform decomposition method for the waveform interpolation (WI) paradigm. The proposed method has the benefit of providing additional scalability in quantization than the existing WI decomposition to meet desired quality requirements. The PSWT is implemented as a quadrature mirror filter bank and decomposes the characteristic waveform surface into a series of reduced time resolution surfaces. Efficient quantization of these surfaces is achieved by exploiting their perceptual importance and inherent transmission rate requirements. The multiresolution representation has the additional benefit of more flexible parameter quantization, allowing a more …

Bounds On The Maximum Determinant For (1,-1) Matrices, C Koukouvinos, M Mitrouli, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We suppose the Hadamard conjecture is true and an Hadamard matrix of order 4t, exists for all t ≥ 1. We use the results for the equivalent SBIBD(4t –1, 2t–1, t–1) to establish the maximum determinant or a lower bound for the maximum determinant for all ±1 matrices. In particular we give numerical results for all orders ≤100.

A New And Efficient Fail—Stop Signature Scheme, Willy Susilo, R. Safavi-Naini, M. Gysin, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Security of ordinary digital signature schemes relies on a computational assumption. Fail-stop signature schemes provide security for a sender against a forger with unlimited computational power by enabling the sender to provide a proof of forgery, if it occurs. In this paper, we give an efficient fail-stop signature scheme that uses two hard problems, discrete logarithm and factorisation, as the basis of receiver's security. We show that the scheme has provable security against adaptively chosen message attack and is the most efficient scheme with respect to the ratio of the message length to the signature length. The scheme provides an …

Semantic Modeling For Video Content-Based Retrieval Systems, L. A. Al Safadi, J. R. Getta

Faculty of Informatics - Papers (Archive)

This work proposes a semantic data model for video documents based on the story-line structure powerful enough to express various human interpretations of video documents, and introduces a formal query language for video retrieval that facilitates retrieval of users' heterogeneous queries based on the proposed model. The paper identifies the elementary semantic units, composite semantic units, associations and abstraction mechanisms necessary for symbolic modeling of semantic video contents. The method is independent of presentation media and it has its origins in symbolic modeling systems developed for database and complex software systems design.

Software Engineering Tools, J. Gray

Faculty of Informatics - Papers (Archive)

Automated tools play an important role in the promotion and adoption of software engineering methods and processes. The development of these tools is itself a significant software engineering task, requiring a considerable investment of time and resources. There are a large number of different kinds of automated software engineering tools, variously known as CASE, CAME, IPSE, SEE, and metaCASE tools. Although these tools differ in the particular methods, activities, and phases of the software development cycle to which they are applied, constructors of these tools often face similar implementation issues. Decisions about host computing platform, implementation language, conformance with standards …

Asymptotic Properties Of Maximum (Composite) Likelihood Estimators For Partially Ordered Markov Models, Hsin-Cheng Huang, Noel A. Cressie

Faculty of Informatics - Papers (Archive)

Partially ordered Markov models (POMMs) are Markov random fields (MRFs) with neighborhood structures derivable from an associated partially ordered set. The most attractive feature of POMMs is that their joint distributions can be written in closed and product form. Therefore, simulation and maximum likelihood estimation for the models is quite straightforward, which is not the case in general for MRF models. In practice, one often has to modify the likelihood to account for edge components; the resulting composite likelihood for POMMs is similarly straightforward to maximize. In this article, we use a martingale approach to derive the asymptotic properties of …

Minimum Phi Divergence Estimator And Hierarchical Testing In Loglinear Models, Noel A. Cressie, Leandro Pardo

Faculty of Informatics - Papers (Archive)

In this paper we consider inference based on very general divergence measures, under assumptions of multinomial sampling and loglinear models. We define the minimum phi divergence estimator, which is seen to be a generalization of the maximum likelihood estimator. This estimator is then used in a phi divergence goodness-of-fit statistic, which is the basis of two new statistics for solving the problem of testing a nested sequence of loglinear models.

Relationships Between Boolean Functions And Symmetric Groups, Chengxin Qu, Jennifer Seberry, Josef Pieprzyk

Faculty of Informatics - Papers (Archive)

We study the relations between boolean functions and symmetric groups. We consider elements of a symmetric group as variable transformations operators for boolean functions. Boolean function may be fixed or permuted by these operators. We give some properties relating the symmetric group S_n and boolean functions on V_n.

Growth In Gaussian Elimination For Weighing Matrices W(N,N-1), C. Koukouvinos, M. Mitrouli, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We consider the values for large minors of a skew-Hadamard matrix or conference matrix W of order n and find maximum n x n minor equals to (n-1)ⁿ/₂, maximum (n-1) x (n-1) minor equals to (n-1)ⁿ/₂-1, maximum (n-2) x (n-2) minor equals 2(n-1)ⁿ/₂-2, and maximum (n-3) x (n-3) minor equals to 4(n-1)ⁿ/₂-3.

This leads us to conjecture that the growth factor for Gaussian elimination of compeletely pivoted skew-Hadamard or conference matrices and indeed any completely pivoted weighing matrix or order n and weight n-1 …

Bounds On The Maximum Determinant For (1,-1) Matrices, C. Koukouvinos, M. Mitrouli, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We suppose the Hadamard conjecture is true and an Hadamard matrix of order 4t, exists for all t ≥ 1. We use the results for the equivalent SBIBD(4t-1,2t-1,t-1) to establish the maximum determinant or a lower bound for the maximum determinant for all ±1 matrices. In particular we give numerical results for all orders ≤100.

An Examination Of The Efficiency Of Australian Crop Variety Evaluation Programmes, Brian R. Cullis, A B. Smith, C Hunt, Arthur R. Gilmour

Faculty of Informatics - Papers (Archive)

In this paper we present the analysis of yield data from a broad cross-section of crop variety evaluation programmes (CVEP) conducted in Australia. The main sources of variety by environment interaction are ` non-static ' interactions, namely those linked to seasonal influences. These contributed an average of 41.3% of the total variance. In contrast the static component accounts for only 5.3% of the total.

We develop methods for determining the relative accuracy of CVEP based on selection of newly promoted entries. The accuracy of the current testing regimes for the Australian CVEP under study is determined. The accuracy of alternative …

Necessary And Sufficient Conditions For Two Variable Orthogonal Designs In Order 44: Addendum, S. Georgiou, C. Koukouvinos, M. Mitrouli, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

In our recent paper Necessary and sufficient conditions for some two variable orthogonal designs in order 44, Koukouvinos, Mitrouli and Seberry leave 7 cases unresolved. Using a new algorithm given in our paper A new algorithm for computer searches for orthogonal designs by the present four authors we are able to finally resolve all these cases. This note records that the necessary conditions for the existence of two variable designs constructed using four circulant matrices are sufficient. In particular of 484 potential cases 404 cases have been found, 68 cases do not exist and 12 cases cannot be constructed using …

Strongbox Secured Secret Sharing Schemes, Jennifer Seberry, A. Penfold Street

Faculty of Informatics - Papers (Archive)

We present one way in which combinatorial designs can be used to give conditionally perfect secret sharing schemes. Schemes formed in this way have the advantage over classical secret sharing schemes of being easily adapted for use as compartmentalized or hierarchical access structures. We study the problem of completion of structures, given partial information, to obtain measures of how closely the behaviour of the secret sharing schemes approaches to ideal behaviour in practice. It may happen that part of a combinatorial design can never be reconstructed from a subset of a minimal defining set. That is, to find the blocks …

Homogeneous Bent Functions, C. Qu, Jennifer Seberry, J. Pieprzyk

Faculty of Informatics - Papers (Archive)

This paper discusses homogeneous bent functions. The space of homogeneous functions of degree three in six boolean variables was exhaustively searched and thirty bent functions were found. These are found to occur in a single orbit under the action of relabelling of the variables. The homogeneous bent functions identified exhibit interesting combinatorial structures and are, to the best of our knowledge, the first examples of bent functions without quadratic terms. A construction for other homogeneous bent functions of degree three in larger spaces is also given.

The Method Of Generalised Conditional Symmetries And Its Various Implementations, J. M. Goard

Faculty of Informatics - Papers (Archive)

We relate Kaptsov's method of B-determining equations for nding invariant solutions of PDEs to the nonclassical method and to the method of generalised conditional symmetries. An extension of Kaptsov's method is then used to nd new solutions of degenerate diusion equations.