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Faculty of Informatics - Papers (Archive)

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Articles 1381 - 1410 of 2013

Full-Text Articles in Physical Sciences and Mathematics

Online Bandwidth Auctions For Efficient Allocation Of Bandwidth, Ying Peng Que, D. Platt Nov 2004

Online Bandwidth Auctions For Efficient Allocation Of Bandwidth, Ying Peng Que, D. Platt

Faculty of Informatics - Papers (Archive)

This paper describes an on-line auction process for dynamic bandwidth allocation in communication networks. The auction is intended to be repeated at short (perhaps ten minute) intervals. The outcome of the auction gives both the bandwidth allocation, and the price to be paid for it. The network is assumed to be MPLS capable, and two variations are provided, one in which a single LSP is available between each source/destination pair, and another in which multiple LSPs are available. We show that the present algorithms are scalable up to about 150 nodes.

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Don't Do What Australia Has Done, R. Nillsen Nov 2004

Don't Do What Australia Has Done, R. Nillsen

Faculty of Informatics - Papers (Archive)

The paper describes and analyses the environment in Australian universities since the changes initiated under the Labor government in 1988 by John Dawkins. It looks at the role and interplay of ideas in the changing intellectual culture in universities, in particular the common effect of the ideas of both liberal economics and postmodernism, and the tensions between corporate values and open enquiry. It raises the issues of the extent to which universities should have a distinct set of values from wider society, and the basis upon which universities should exist as distinctive institutions.

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Weighted Segmented Digital Watermarking, Glen Wheeler, R. Safavi-Naini, N. P. Sheppard Oct 2004

Weighted Segmented Digital Watermarking, Glen Wheeler, R. Safavi-Naini, N. P. Sheppard

Faculty of Informatics - Papers (Archive)

We introduce the notion of weighted watermarking for proof-of-ownership watermark protection of multimedia works that are the product of more than one author and where each author is considered to be of different importance relative to the other authors. We specifically examine weighted segmented watermarking for still images and generalise previous work on performance measurement of watermark embedding patterns in the presence of cropping attacks.

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Import/Export In Digital Rights Management, R. Safavi-Naini, N. P. Sheppard, Takeyuki Uehara Oct 2004

Import/Export In Digital Rights Management, R. Safavi-Naini, N. P. Sheppard, Takeyuki Uehara

Faculty of Informatics - Papers (Archive)

The inherently controlled nature of digital rights management systems does little to promote inter-operability of systems provided by different vendors. In this paper, we consider import and export functionality by which multimedia protected by one digital rights management regime can be made available to a multimedia device that supports a different digital rights management regime, without compromising the protection afforded to the content under the original regime. We first identify specific issues to be addressed by developers of digital rights management import/export regimes and outline a variety of methods by which these regimes may be implemented. We then apply our …

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Image Database Retrieval Using Sketched Queries, A. Chalechale, G. Naghdy, Prashan Premaratne Oct 2004

Image Database Retrieval Using Sketched Queries, A. Chalechale, G. Naghdy, Prashan Premaratne

Faculty of Informatics - Papers (Archive)

This paper presents a novel approach for sketch-based image retrieval based on low-level features. It enables the measuring of the similarity among full color multi-component images within a database (models) and simple black and white user sketched queries. It needs no cost intensive image segmentation. Strong edges of the model image and morphologically thinned version of the query image are used for image abstraction. Angular-radial decomposition of pixels in the abstract images is used to extract new compact and affine invariant features. Comparative results, employing an art database (ArT BANK), show significant improvement in average normalized modified retrieval rank (ANMRR) …

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De-Cumulant Based Approaches For Convolutive Blind Source Separation, T. Mei, Jiangtao Xi, Joe F. Chicharo, F. Yin Oct 2004

De-Cumulant Based Approaches For Convolutive Blind Source Separation, T. Mei, Jiangtao Xi, Joe F. Chicharo, F. Yin

Faculty of Informatics - Papers (Archive)

This paper studies the blind separation of signal sources (BSS) based on the approach of de-cumulant. It considers the cases where independent signal sources are mixed through convolutive mixing system with unity autochannel frequency responses and causal cross-channel FIR filters. Firstly, it tries to show that the de-cumulant is sufficient for separation. Secondly, novel algorithms are developed based on zero-forcing of cross-cumulant pairs. These algorithms are developed in the time-domain and so there is not the frequency permutation ambiguity problem usually suffered by most of the frequency-domain algorithms. Simulation results are presented to support the validity of the proposed algorithms.

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Decorrelation: Sufficient For Convolutive Blind Source Separation?, Jiangtao Xi, T. Mei, Joe F. Chicharo, F. Yin Oct 2004

Decorrelation: Sufficient For Convolutive Blind Source Separation?, Jiangtao Xi, T. Mei, Joe F. Chicharo, F. Yin

Faculty of Informatics - Papers (Archive)

This paper considers blind separation of signal sources in a convolutive mixing environment. It tries to show that decorrelation is sufficient for separation of convolutively mixed sources. Two algorithms are also proposed and tested by computer simulations.

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Blur Retrieval Via Separation Of Zeros Sheets From Noisy Blurred Images, Prashan Premaratne, I. Burnett, C. D. Liyanage Oct 2004

Blur Retrieval Via Separation Of Zeros Sheets From Noisy Blurred Images, Prashan Premaratne, I. Burnett, C. D. Liyanage

Faculty of Informatics - Papers (Archive)

A novel method of separating the point spread function from blurred images using zeros of the Z transform is presented when more than one blurred image is available. The proposed method is demonstrated to be effective with significant contamination with signal-to-noise ratios of over 30 dB. This method holds much promise as a blind deconvolution (i.e. problem of recovering two functions from their convolution) technique, as it does not impose any constraints on the point spread function, such as positivity. The article is presented with experimental results over different signal-to-noise ratios, depicting its effectiveness as a practical image restoration technique.

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Power Quality Waveform Generator Based On The Csound Software Sound Synthesizer, J. P. Braun, V. J. Gosbell, S. Perera Sep 2004

Power Quality Waveform Generator Based On The Csound Software Sound Synthesizer, J. P. Braun, V. J. Gosbell, S. Perera

Faculty of Informatics - Papers (Archive)

Power quality investigations in the laboratory often require waveform generators capable of recreating the various disturbances present in an electrical system. These sources of waveforms are generally based on arbitrary waveform generators (AWG) because of the great flexibility they offer. However, AWGs are generally not well suited for time varying waveforms because of the limited size of their memory. To circumvent this limitation, a real time waveform synthesizer is required, but their applicability is generally limited by cost. This paper presents the use of CSound, a software sound synthesizer to achieve this aim in a cost effective manner. This paper …

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Primary And Secondary Indices For Power Quality (Pq) Survey Reporting, V. J. Gosbell, S. Perera, Robert A. Barr, Alex Baitch Sep 2004

Primary And Secondary Indices For Power Quality (Pq) Survey Reporting, V. J. Gosbell, S. Perera, Robert A. Barr, Alex Baitch

Faculty of Informatics - Papers (Archive)

Routine monitoring involves many PQ monitors at fixed sites with readings able to be interrogated remotely and downloaded to a central database. The amount of data for one year is large, and innovative methods are needed to ensure that it can give useful insights. Primary indices are proposed to show whether a site is acceptable to specified standards and are mainly based on 95% values. Secondary indices are proposed to give additional insights. For variations, indices are proposed to give a measure of the impact on customer equipment beyond that incorporated in standards. Sag secondary indices are defined to give …

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Benchmarking Utilities For The Impact Of Voltage Sags On Customers, H. M. Herath, V. J. Gosbell, S. Perera Sep 2004

Benchmarking Utilities For The Impact Of Voltage Sags On Customers, H. M. Herath, V. J. Gosbell, S. Perera

Faculty of Informatics - Papers (Archive)

Most utilities have increased their focus on voltage sags as the sags account for vast majority of recorded equipment trips. Although these events are not necessarily the most frequent, they have a tremendous economic impact on end-users. The process of benchmarking customer voltage sag levels generally requires voltage sag monitoring data for a period of minimum one year. This data can then be quantified to relate voltage sag performance with standardized limits for acceptable performance. This work suggests a methodology for benchmarking the impact of voltage sags on customers of different utilities by means of a three stage reporting procedure …

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Computation Of The Free Distance And Low Weight Distribution Of Turbo Codes With Convolutional Interleavers, Sina Vafi, Tadeusz A. Wysocki Sep 2004

Computation Of The Free Distance And Low Weight Distribution Of Turbo Codes With Convolutional Interleavers, Sina Vafi, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

This work presents an algorithm for computation of the free distance parameter of turbo codes with a convolutional interleaver implemented to act as a block interleaver. Based on the properties of the interleaver and the algorithm applied, we can also determine the other low weights of turbo codes and this is useful in determining the performance of the error floor of turbo codes. For different turbo code structures, the relevant parameters have been computed. The error rate simulations confirm the algorithm results.

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A Scalable And Oblivious Digital Watermarking For Images, W. Lu, R. Safavi-Naini, Takeyuki Uehara, Wanqing Li Aug 2004

A Scalable And Oblivious Digital Watermarking For Images, W. Lu, R. Safavi-Naini, Takeyuki Uehara, Wanqing Li

Faculty of Informatics - Papers (Archive)

Scalable compression algorithms, such as JPEG, can compress images to different quality or resolution levels so that the target systems with different display capabilities, can display the image. Digital watermarking is widely used for protection of copyright and identification of ownership on digital images. It is desirable to have scalable watermarking systems, where the watermark is detectable when the watermarked image is at low quality or low resolution levels. This paper presents an oblivious block-based spread-spectrum-like watermarking system which is robust against scalable JPEG compression, cropping and shifting. The system is secure against the common watermarking attacks. Experimental results support …

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A Semi-Supervised Map Segmentation Of Brain Tissues, Wanqing Li, C. Desilver, Y. Attikiouzel Aug 2004

A Semi-Supervised Map Segmentation Of Brain Tissues, Wanqing Li, C. Desilver, Y. Attikiouzel

Faculty of Informatics - Papers (Archive)

This paper presents a method for semi-supervised MAP (maximum a-posterior probability) segmentation of brain tissues where labelled data are available for either all types of tissues or only a few types of tissues possibly at different levels of quality. The proposed MAP segmentation takes supervised and unsupervised segmentation as its two special cases where, respectively, quality labelled data is available or there is no labelled data at all. Experiments on real MR images have shown that the proposed method improved the segmentation accuracy substantially with only a few labelled data in comparison with both fully supervised method with the same …

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Space Time Spreading With Modified Walsh-Hadamard Sequences, Peter James Vial, Beata J. Wysocki, I. Raad, Tadeusz A. Wysocki Aug 2004

Space Time Spreading With Modified Walsh-Hadamard Sequences, Peter James Vial, Beata J. Wysocki, I. Raad, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

Previous work has shown that the performance of a space time spreading (STS) system using Walsh codes with two transmit antennas at the base station (BS) is degraded in the presence of mutual interference from adjacent sectors in the same cell. We use modified Walsh-Hadamard sequences exhibiting improved cross-correlation performance, which potentially mitigates the effects of MAI (multiple access interference). The presented study also looks at variation of sets of different modified Walsh-Hadamard codes being used by the adjacent interferer, with a hundred randomly selected pairings being chosen, as well as the case where one set of alternate codes is …

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Distributed, Collaborative Learning Environments Using Ad Hoc Networks, A. Fuller, Penelope Mcfarlane, D. F. Saffioti Aug 2004

Distributed, Collaborative Learning Environments Using Ad Hoc Networks, A. Fuller, Penelope Mcfarlane, D. F. Saffioti

Faculty of Informatics - Papers (Archive)

Computer assisted distributed or collaborative learning environments have been in existence for some time, however one impediment to more widespread use has been the need for a permanent wired network infrastructure. In this paper we discuss the development of a prototype tool that allows the formation of an ad hoc network at any time, and in any locale.

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Living With Inconsistencies In A Multidatabase System, J. R. Getta Aug 2004

Living With Inconsistencies In A Multidatabase System, J. R. Getta

Faculty of Informatics - Papers (Archive)

Integration of autonomous sources of information is one of the most important problems in implementation of the global information systems. This paper considers multidatabase systems as one of the typical architectures of global information services and addresses a problem of storing and processing inconsistent information in such systems. A new data model proposed in the paper separates sure from inconsistent information and introduces a system of elementary operations on the containers with sure and inconsistent information. A review of the implementation aspects in an environment of a typical relational database management system concludes the paper.

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A Supervised Self-Organizing Map For Structures, Markus Hagenbuchner, Ah Chung Tsoi Jul 2004

A Supervised Self-Organizing Map For Structures, Markus Hagenbuchner, Ah Chung Tsoi

Faculty of Informatics - Papers (Archive)

This work proposes an improvement of a supervised learning technique for self organizing maps. The ideas presented in This work differ from Kohonen's approach to supervision in that a.) a rejection term is used, and b.) rejection affects the training only locally. This approach produces superior results because it does not affect network weights globally, and hence, prevents the addition of noise to the learning process of remote neurons. We implemented the ideas into self-organizing maps for structured data (SOM-SD) which is a more general form of self-organizing maps capable of processing graphs. The capabilities of the proposed ideas are …

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Integration Of Dft And Cosine-Modulated Filter Banks With Blind Separation Of Convolutively Mixed Non-Stationary Sources, I. Russell, Jiangtao Xi, Alfred Mertins, Joe F. Chicharo Jul 2004

Integration Of Dft And Cosine-Modulated Filter Banks With Blind Separation Of Convolutively Mixed Non-Stationary Sources, I. Russell, Jiangtao Xi, Alfred Mertins, Joe F. Chicharo

Faculty of Informatics - Papers (Archive)

In this paper, oversampled M channel FIR filter banks using both DFT modulation and cosine modulation designs are used in conjunction with a time domain blind source separation (BSS) algorithm I. Russell et al., (2003). This BSS algorithm has been shown to blindly separate the fullband versions of non-stationary convolutively mixed sources in the time domain. However further savings on convergence and computational complexity can be made by using subband decomposition on the mixed signals before implementation of the time domain BSS algorithm in each subband. An extended lapped transform (ELT) prototype is modulated using a cosine-modulated (CM) FIR filter …

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A Vision System For Providing 3d Perception Of The Environment Via: Transcutaneous Electro-Neural Stimulation, S. Meers, Koren Ward Jul 2004

A Vision System For Providing 3d Perception Of The Environment Via: Transcutaneous Electro-Neural Stimulation, S. Meers, Koren Ward

Faculty of Informatics - Papers (Archive)

The development of effective user interfaces, appropriate sensors, and information processing techniques for enabling the blind to achieve additional perception of the environment is a relentless challenge confronting HCI and sensor researchers. To address this challenge we have developed a novel 3D vision system that can enable the 3D structure of the immediate environment to be perceived via head mounted stereo video cameras and electro-tactile data gloves without requiring any use of the eyes. The electro-neural vision system (ENVS) works by extracting a depth map from the camera images by measuring the disparity between the stereo images. This range data …

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The Effect Of Imperfect Carrier Recovery On The Performance Of The Diversity Antenna Selection Technique In Wireless Channels Utilizing Dstm, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins Jul 2004

The Effect Of Imperfect Carrier Recovery On The Performance Of The Diversity Antenna Selection Technique In Wireless Channels Utilizing Dstm, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins

Faculty of Informatics - Papers (Archive)

This paper examines the effect of imperfect carrier phase/frequency recovery at the receiver on the bit error performance of our diversity antenna selection technique (AST) proposed for channels utilizing differential space-time modulation (DSTM). The tolerance of differential detection associated with the proposed AST to phase/frequency errors is then analyzed.

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Multi-Modulation Schemes To Increase The Rate Space-Time Block Codes In Rayleigh Fading Channels, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins Jun 2004

Multi-Modulation Schemes To Increase The Rate Space-Time Block Codes In Rayleigh Fading Channels, Le Chung Tran, Tadeusz A. Wysocki, Alfred Mertins

Faculty of Informatics - Papers (Archive)

The paper examines multimodulation schemes (MMSs) to increase the rate of our two new complex orthogonal designs (CODs) proposed for eight transmit antennas, namely C/sub 1/ and C/sub 2/, corresponding to the Amicable Orthogonal Designs (AODs) (8;1,1,2,2;1,1,2,2) and (8;1,1,1,4;1,1,1,4), respectively. In addition, the optimal intersymbol power allocation in the proposed codes in single modulation as well as in MMSs in flat Rayleigh fading channels is considered. It turns out that, in some modulation schemes, equal power transmission per each symbol time slot is not only optimal from the technical point of view, but also optimal in terms of achieving the …

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Chain-Based Extraction Of Line Segments To Describe Images, A. Chalechale, G. Naghdy, Prashan Premaratne, H. Moghaddasi Jun 2004

Chain-Based Extraction Of Line Segments To Describe Images, A. Chalechale, G. Naghdy, Prashan Premaratne, H. Moghaddasi

Faculty of Informatics - Papers (Archive)

This work presents a novel fast method for line segment extraction, based on a chain code representation of edge maps. It has a parallel nature and can be employed on parallel machines. In the first phase it breaks the macro chains into several micro chains after applying shifting, smoothing and differentiating. The micro chains are then approximated by straight line segments. In the second phase, based on the length and the error criteria, the line segments are grouped into much longer lines. The experimental results show a significant improvement in the number of line segments extracted while their accumulative length …

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An Mpeg Tolerant Authentication System For Video Data, Takeyuki Uehara, R. Safavi-Naini, P. Ogunbona Jun 2004

An Mpeg Tolerant Authentication System For Video Data, Takeyuki Uehara, R. Safavi-Naini, P. Ogunbona

Faculty of Informatics - Papers (Archive)

We propose a secure video authentication algorithm that is tolerant to visual degradation due to MPEG lossy compression to a designed level. The authentication process generates a tag that is sent with video data and the level of protection can be adjusted so that longer tags are used for higher security, and that the protection is distributed such that higher security is provided for regions of interest in the image. The computation required for authentication and verification can be largely performed as part of MPEG compression and so generation and verification of the tag can be integrated into the compression …

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Document Image Analysis And Verification Using Cursive Signature, A. Chalechale, G. Naghdy, Prashan Premaratne, Alfred Mertins Jun 2004

Document Image Analysis And Verification Using Cursive Signature, A. Chalechale, G. Naghdy, Prashan Premaratne, Alfred Mertins

Faculty of Informatics - Papers (Archive)

A new approach for document image analysis and verification is presented. The approach utilizes connected component analysis and geometric properties of labelled regions for region of interest extraction. Document images containing Persian/Arabic text combined with English text, headlines, ruling lines, trade mark and cursive signature are used as a test data. Persian/Arabic signature extraction is investigated as a case study. The proposed method uses special characteristics of such signatures for extraction and verification procedures. A set of efficient, invariant and compact features is extracted utilizing spatial partitioning of the signature region. Comparative results exhibit high extraction and verification rates.

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Two Complex Orthogonal Space-Time Codes For Eight Transmit Antennas, Le Chung Tran, Jennifer Seberry, Yejing Wang, Beata J. Wysocki, T. A. Wysocki, Tianbing Xia, Ying Zhao Jun 2004

Two Complex Orthogonal Space-Time Codes For Eight Transmit Antennas, Le Chung Tran, Jennifer Seberry, Yejing Wang, Beata J. Wysocki, T. A. Wysocki, Tianbing Xia, Ying Zhao

Faculty of Informatics - Papers (Archive)

Two new constructions of complex orthogonal space-time block codes of order 8 based on the theory of amicable orthogonal designs are presented and their performance compared with that of the standard code of order 8. These new codes are suitable for multi-modulation schemes where the performance can be sacrificed for a higher throughput.

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Orthogonal Designs Of Kharaghani Type: Ii, C. Koukouvinos, Jennifer Seberry Jun 2004

Orthogonal Designs Of Kharaghani Type: Ii, C. Koukouvinos, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

H. Kharaghani, in "Arrays for orthogonal designs", J. Combin. Designs, 8 (2000), 166-173, showed how to use amicable sets of matrices to construct orthogonal designs in orders divisible by eight. We show how amicable orthogonal designs can be used to make amicable sets and so obtain infinite families of orthogonal designs in six variables in orders divisible by eight.

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The Importance Of Conducting Geodemographic Market Analysis On Coastal Areas: A Pilot Study Using Kiama Council, Katina Michael Jun 2004

The Importance Of Conducting Geodemographic Market Analysis On Coastal Areas: A Pilot Study Using Kiama Council, Katina Michael

Faculty of Informatics - Papers (Archive)

In February of 2003 Kiama Council launched a preliminary survey to gather community attitudes on the future growth of Werri Beach and Gerringong, NSW (Nelson). The survey focused primarily on what actions Council should take to manage population growth within existing neighbourhoods. This paper aims to support the preliminary survey by proposing that a geodemographic market analysis be conducted to complement the findings of the study published in May 2003 (Wiggins). The use of a Geographic Information System (GIS) can add great value to the strategic decisionmaking process and it is the recommendation of this paper that GIS should become …

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Further Results On Strongbox Secured Secret Sharing Schemes, G. Gamble, B. M. Maenhaut, Jennifer Seberry, A. Penfold Street Jun 2004

Further Results On Strongbox Secured Secret Sharing Schemes, G. Gamble, B. M. Maenhaut, Jennifer Seberry, A. Penfold Street

Faculty of Informatics - Papers (Archive)

We extend our earlier work on ways in which defining sets of combinatorial designs can be used to create secret sharing schemes. We give an algorithm for classifying defining sets of designs according to their security properties and summarise the results of this algorithm for many small designs. Finally, we discuss briefly how defining sets can be applied to variations of the basic secret sharing scheme.

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Homogeneous Bent Functions Of Degree N In 2n Variables Do Not Exist For N > 3 , Tianbing Xia, Jennifer Seberry, J. Pieprzyk, C. Charnes Jun 2004

Homogeneous Bent Functions Of Degree N In 2n Variables Do Not Exist For N > 3 , Tianbing Xia, Jennifer Seberry, J. Pieprzyk, C. Charnes

Faculty of Informatics - Papers (Archive)

We prove that homogeneous bent functions f : GF(2)2n —> GF(2) of degree n do not exist for n > 3. Consequently homogeneous bent functions must have degree < n for n > 3.

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