Armand, S, Blumenstein, M & Muthukkumarasamy, V 2007, 'Off-line Signature Verification Using an Enhanced Modified Direction Feature with Single and Multi-classifier Approaches', IEEE Computational Intelligence Magazine, vol. 2, no. 2, pp. 18-25.
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A study was conducted to investigate the effectiveness of Modified Direction Feature (MDF) for performing off-line signature verification and dome modifications to the extracted features were proposed. The study was conducted by combining the 'Grupo de Procesado Digital de Senales' (GPDS) signature database and additional signatures collected by the researchers. A total of 2376 sample signatures were used to conduct the study. Reseahers used 44 sets of signatures, with 24 samples of genuine and 30 samples of forged signatures used. The binary image of each signature was processed, and edges extracted, providing the first step of reducing the amount of data that described each pattern. MDF and additional features were proposed to provide significant information for the signature verification problem.
Blumenstein, M, Liu, XY & Verma, B 2007, 'An investigation of the modified direction feature for cursive character recognition', Pattern Recognition, vol. 40, no. 2, pp. 376-388.
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This paper describes and analyses the performance of a novel feature extraction technique for the recognition of segmented/cursive characters that may be used in the context of a segmentation-based handwritten word recognition system. The modified direction feature (MDF) extraction technique builds upon the direction feature (DF) technique proposed previously that extracts direction information from the structure of character contours. This principal was extended so that the direction information is integrated with a technique for detecting transitions between background and foreground pixels in the character image. In order to improve on the DF extraction technique, a number of modifications were undertaken. With a view to describe the character contour more effectively, a re-design of the direction number determination technique was performed. Also, an additional global feature was introduced to improve the recognition accuracy for those characters that were most frequently confused with patterns of similar appearance. MDF was tested using a neural network-based classifier and compared to the DF and transition feature (TF) extraction techniques. MDF outperformed both DF and TF techniques using a benchmark dataset and compared favourably with the top results in the literature. A recognition accuracy of above 89% is reported on characters from the CEDAR dataset. © 2006 Pattern Recognition Society.
Browne, M, Castelle, B, Strauss, D, Tomlinson, R, Blumenstein, M & Lane, C 2007, 'Near-shore swell estimation from a global wind-wave model: Spectral process, linear, and artificial neural network models', Coastal Engineering, vol. 54, no. 5, pp. 445-460.
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Estimation of swell conditions in coastal regions is important for a variety of public, government, and research applications. Driving a model of the near-shore wave transformation from an offshore global swell model such as NOAA WaveWatch3 is an economical means to arrive at swell size estimates at particular locations of interest. Recently, some work (e.g. Browne et al. [Browne, M., Strauss, D., Castelle, B., Blumenstein, M., Tomlinson, R., 2006. Local swell estimation and prediction from a global wind-wave model. IEEE Geoscience and Remote Sensing Letters 3 (4), 462-466.]) has examined an artificial neural network (ANN) based, empirical approach to wave estimation. Here, we provide a comprehensive evaluation of two data driven approaches to estimating waves near-shore (linear and ANN), and also contrast these with a more traditional spectral wave simulation model (SWAN). Performance was assessed on data gathered from a total of 17 near-shore locations, with heterogenous geography and bathymetry, around the continent of Australia over a 7 month period. It was found that the ANNs out-performed SWAN and the non-linear architecture consistently out-performed the linear method. Variability in performance and differential performance with regard to geographical location could largely be explained in terms of the underlying complexity of the local wave transformation. © 2006 Elsevier B.V. All rights reserved.
Devitt, SJ, Greentree, AD, Ionicioiu, R, O'Brien, JL, Munro, WJ & Hollenberg, LCL 2007, 'The Photonic Module: an on-demand resource for photonic entanglement', Phys. Rev. A., vol. 76, no. 5, p. 052312.
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Photonic entanglement has a wide range of applications in quantum computationand communication. Here we introduce a new device: the 'photonic module', whichallows for the rapid, deterministic preparation of a large class of entangledphoton states. The module is an application independent, 'plug and play'device, with sufficient flexibility to prepare entanglement for all majorquantum computation and communication applications in a completelydeterministic fashion without number-discriminated photon detection. We presenttwo alternative constructions for the module, one using free-space componentsand one in a photonic bandgap structures. The natural operation of the moduleis to generate states within the stabilizer formalism and we present ananalysis on the cavity-QED requirements to experimentally realize this device.
Devitt, SJ, Schirmer, SG, Oi, DKL, Cole, JH & Hollenberg, LCL 2007, 'Subspace Confinement: How good is your qubit?', New J. Phys., vol. 9, p. 384.
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The basic operating element of standard quantum computation is the qubit, anisolated two-level system that can be accurately controlled, initialized andmeasured. However, the majority of proposed physical architectures for quantumcomputation are built from systems that contain much more complicated Hilbertspace structures. Hence, defining a qubit requires the identification of anappropriate controllable two-dimensional sub-system. This prompts the obviousquestion of how well a qubit, thus defined, is confined to this subspace, andwhether we can experimentally quantify the potential leakage into to statesoutside the qubit subspace. In this paper we demonstrate that subspace leakagecan be quantitatively characterized using minimal theoretical assumptions byexamining the Fourier spectrum of the Rabi oscillation experiment.
Duan, R, Feng, Y & Ying, M 2007, 'Entanglement is not necessary for perfect discrimination between unitary operations', PHYSICAL REVIEW LETTERS, vol. 98, no. 10, pp. 1-4.
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We show that a unitary operation (quantum circuit) secretly chosen from a finite set of unitary operations can be determined with certainty by sequentially applying only a finite amount of runs of the unknown circuit. No entanglement or joint quantum operations are required in our scheme. We further show that our scheme is optimal in the sense that the number of the runs is minimal when discriminating only two unitary operations. © 2007 The American Physical Society.
Duan, R, Feng, Y & Ying, M 2007, 'Entanglement is not necessary for perfect discrimination between unitary operations (vol 98, pg 100503, 2007)', PHYSICAL REVIEW LETTERS, vol. 98, no. 12.
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Duan, R, Feng, Y & Ying, M 2007, 'Entanglement is not necessary for perfect discrimination between unitary operations.', Phys Rev Lett, vol. 98, no. 10, p. 100503.
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We show that a unitary operation (quantum circuit) secretly chosen from a finite set of unitary operations can be determined with certainty by sequentially applying only a finite amount of runs of the unknown circuit. No entanglement or joint quantum operations are required in our scheme. We further show that our scheme is optimal in the sense that the number of the runs is minimal when discriminating only two unitary operations.
Duan, R, Feng, Y & Ying, M 2007, 'Local Distinguishability of Multipartite Unitary Operations', Phys. Rev. Lett., vol. 100, no. 2, p. 020503.
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We show that any two different unitary operations acting on an arbitrarymultipartite quantum system can be perfectly distinguishable by localoperations and classical communication when a finite number of runs is allowed.We then directly extend this result into the case when the number of unitaryoperations to be discriminated is more than two. Intuitively, our result meansthat the lost identity of a nonlocal (entangled) unitary operation can berecovered locally, without any use of entanglement or joint quantum operations.
Duan, R, Feng, Y, Ji, Z & Ying, M 2007, 'Distinguishing arbitrary multipartite basis unambiguously using local operations and classical communication', PHYSICAL REVIEW LETTERS, vol. 98, no. 23, pp. 1-4.
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We show that an arbitrary basis of a multipartite quantum state space consisting of K distant parties such that the kth party has local dimension dk always contains at least N=∑k=1K(dk-1)+1 members that are unambiguously distinguishable using local operations and classical communication (LOCC). We further show that this lower bound is optimal by analytically constructing a special product basis having only N members unambiguously distinguishable by LOCC. Interestingly, such a special product basis not only gives a stronger form of the weird phenomenon 'nonlocality without entanglement,' but also implies the existence of a locally distinguishable entangled basis. © 2007 The American Physical Society.
Duan, R, Feng, Y, Ji, Z & Ying, M 2007, 'Distinguishing arbitrary multipartite basis unambiguously using local operations and classical communication (vol 98, art no 230602, 2007)', PHYSICAL REVIEW LETTERS, vol. 99, no. 1.
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Feng, Y, Duan, R, Ji, Z & Ying, M 2007, 'Probabilistic bisimulations for quantum processes', INFORMATION AND COMPUTATION, vol. 205, no. 11, pp. 1608-1639.
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Modeling and reasoning about concurrent quantum systems is very important for both distributed quantum computing and quantum protocol verification. As a consequence, a general framework formally describing communication and concurrency in complex quantum
Feng, Y, Duan, R, Ji, Z & Ying, M 2007, 'Proof rules for the correctness of quantum programs', THEORETICAL COMPUTER SCIENCE, vol. 386, no. 1-2, pp. 151-166.
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We apply the notion of quantum predicate proposed by D'Hondt and Panangaden to analyze a simple language fragment which may describe the quantum part of a future quantum computer in Knill's architecture. The notion of weakest liberal precondition semanti
Ferrie, C & Emerson, J 2007, 'Frame representations of quantum mechanics and the necessity of negativity in quasi-probability representations', J. Phys. A: Math. Theor., vol. 41, no. 35, p. 352001.
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Several finite dimensional quasi-probability representations of quantumstates have been proposed to study various problems in quantum informationtheory and quantum foundations. These representations are often defined only onrestricted dimensions and their physical significance in contexts such asdrawing quantum-classical comparisons is limited by the non-uniqueness of theparticular representation. Here we show how the mathematical theory of framesprovides a unified formalism which accommodates all known quasi-probabilityrepresentations of finite dimensional quantum systems. Moreover, we show thatany quasi-probability representation satisfying two reasonable properties isequivalent to a frame representation and then prove that any suchrepresentation of quantum mechanics must exhibit either negativity or adeformed probability calculus.
Hsieh, M-H, Devetak, I & Brun, T 2007, 'General entanglement-assisted quantum error-correcting codes', Phys. Rev. A, vol. 76, no. 6, p. 062313.
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Entanglement-assisted quantum error-correcting codes (EAQECCs) make use ofpre-existing entanglement between the sender and receiver to boost the rate oftransmission. It is possible to construct an EAQECC from any classical linearcode, unlike standard QECCs which can only be constructed from dual-containingcodes. Operator quantum error-correcting codes (OQECCs) allow certain errors tobe corrected (or prevented) passively, reducing the complexity of thecorrection procedure. We combine these two extensions of standard quantum errorcorrection into a unified entanglement-assisted quantum error correctionformalism. This new scheme, which we call entanglement-assisted operatorquantum error correction (EAOQEC), is the most general and powerful quantumerror-correcting technique known, retaining the advantages of bothentanglement-assistance and passive correction. We present the formalism, showthe considerable freedom in constructing EAOQECCs from classical codes, anddemonstrate the construction with examples.
Lanyon, BP, Weinhold, TJ, Langford, NK, Barbieri, M, James, DFV, Gilchrist, A & White, AG 2007, 'Experimental Demonstration of a Compiled Version of Shor’s Algorithm with Quantum Entanglement', Physical Review Letters, vol. 99, no. 25.
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Lee, T & Shraibman, A 2007, 'Disjointness is hard in the multi-party number on the forehead model', Proceedings of the Annual IEEE Conference on Computational Complexity, pp. 81-91.
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We show that disjointness requires randomized communicationOmega(n^{1/(k+1)}/2^{2^k}) in the general k-party number-on-the-forehead modelof complexity. The previous best lower bound for k >= 3 was log(n)/(k-1). Ourresults give a separation between nondeterministic and randomized multipartynumber-on-the-forehead communication complexity for up to k=log log n - O(loglog log n) many players. Also by a reduction of Beame, Pitassi, and Segerlind,these results imply subexponential lower bounds on the size of proofs needed torefute certain unsatisfiable CNFs in a broad class of proof systems, includingtree-like Lovasz-Schrijver proofs.
Lee, T & Shraibman, A 2007, 'Lower Bounds in Communication Complexity', Foundations and Trends in Theoretical Computer Science, vol. 3, no. 4, pp. 263-399.
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Li, S 2007, 'A representation theorem for minmax regret policies', Artificial Intelligence, vol. 171, no. 1, pp. 19-24.
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Decision making under uncertainty is one of the central tasks of artificial agents. Due to their simplicity and ease of specification, qualitative decision tools are popular in artificial intelligence. Brafman and Tennenholtz [R.I. Brafman, M. Tennenholtz, An axiomatic treatment of three qualitative decision criteria, J. ACM 47 (3) (2000) 452482] model an agent's uncertain knowledge as her local state, which consists of states of the world that she deems possible. A policy determines for each local state a total preorder of the set of actions, which represents the agent's preference over these actions. It is known that a policy is maximin representable if and only if it is closed under unions and satisfies a certain acyclicity condition. In this paper we show that the above conditions, although necessary, are insufficient for minmax regret and competitive ratio policies. A complete characterization of these policies is obtained by introducing the best-equally strictness.
Li, S & Nebel, B 2007, 'Qualitative Spatial Representation and Reasoning: A Hierarchical Approach', The Computer Journal, vol. 50, no. 4, pp. 391-402.
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The ability to reason in space is crucial for agents in order to make informed decisions. Current high-level qualitative approaches to spatial reasoning have serious deficiencies in not reflecting the hierarchical nature of spatial data and human spatial cognition. This article proposes a framework for hierarchical representation and reasoning about topological information, where a continuous model of space is approximated by a collection of discrete sub-models, and spatial information is hierarchically represented in discrete sub-models in a rough set manner. The work is based on the Generalized Region Connection Calculus theory, where continuous and discrete models of space are coped in a unified way. Reasoning issues such as determining the mereological (part-whole) relations between two rough regions are also discussed. Moreover, we consider an important problem that is closely related to map generalization in cartography and Geographical Information Science. Given a spatial configuration at a finer level, we show how to construct a configuration at a coarser level while preserving the mereological relations. © The Author 2007. Published by Oxford University Press on behalf of The British Computer Society. All rights reserved.
Resch, KJ, O’Brien, JL, Weinhold, TJ, Sanaka, K, Lanyon, BP, Langford, NK & White, AG 2007, 'Entanglement Generation by Fock-State Filtration', Physical Review Letters, vol. 98, no. 20.
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White, AG, Gilchrist, A, Pryde, GJ, O'Brien, JL, Bremner, MJ & Langford, NK 2007, 'Measuring two-qubit gates', JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, vol. 24, no. 2, pp. 172-183.
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Xin, Y & Duan, R 2007, 'Conditions for entanglement transformation between a class of multipartite pure states with generalized Schmidt decompositions', PHYSICAL REVIEW A, vol. 76, no. 4, pp. 1-3.
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We generalize Nielsen's majorization criterion for the convertibility of bipartite pure states to a special class of multipartite pure states with generalized Schmidt decompositions. © 2007 The American Physical Society.
Ying, M, Chen, J, Feng, Y & Duan, R 2007, 'Commutativity of quantum weakest preconditions', INFORMATION PROCESSING LETTERS, vol. 104, no. 4, pp. 152-158.
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The notion of quantum weakest precondition was introduced by D'Hondt and P. Panangaden [E. D'Hondt, P. Panangaden, Quantum weakest preconditions, Mathematical Structures in Computer Science 16 (2006) 429-451], and they presented a representation of weake
Brun, T, Devetak, I & Hsieh, M 1970, 'Quantum quasi-cyclic low-density parity-check codes', The 7th Asian Conference on Quantum Information Science (AQIS07), Shiran Kaikan, Kyoto University, Japan.
Brun, TA, Devetak, I & Hsieh, M-H 1970, 'General entanglement-assisted quantum error-correcting codes', 2007 IEEE International Symposium on Information Theory, 2007 IEEE International Symposium on Information Theory, IEEE, Nice, France, pp. 2101-2105.
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Entanglement-assisted quantum error-correcting codes (EAQECCs) make use of pre-existing entanglement between the sender and receiver to boost the rate of transmission. It is possible to construct an EAQECC from any classical linear code, unlike standard QECCs which can only be constructed from dual-containing codes. Operator quantum error-correcting codes (OQECCs) allow certain errors to be corrected (or prevented) passively, reducing the complexity of the correction procedure. We combine these two extensions of standard quantum error correction into a unified entanglement-assisted quantum error correction formalism. This new scheme, which we call entanglement-assisted operator quantum error correction (EAOQEC), is the most general and powerful quantum error-correcting technique known, retaining the advantages of both entanglement-assistance and passive correction. We present the formalism, show the considerable freedom in constructing EAOQECCs from classical codes, and demonstrate the construction with examples. ©2007 IEEE.
Childs, AM & Lee, T 1970, 'Optimal quantum adversary lower bounds for ordered search', Proc. 35th International Colloquium on Automata, Languages and Programming (ICALP 2008), Lecture Notes in Computer Science 5125, pp. 869-880, International Colloquium on Automata, Languages, and Programming, Springer Berlin Heidelberg, Reykjavik, Iceland, pp. 869-880.
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The goal of the ordered search problem is to find a particular item in anordered list of n items. Using the adversary method, Hoyer, Neerbek, and Shiproved a quantum lower bound for this problem of (1/pi) ln n + Theta(1). Here,we find the exact value of the best possible quantum adversary lower bound fora symmetrized version of ordered search (whose query complexity differs fromthat of the original problem by at most 1). Thus we show that the best lowerbound for ordered search that can be proved by the adversary method is (1/pi)ln n + O(1). Furthermore, we show that this remains true for the generalizedadversary method allowing negative weights.
Green, S & Blumenstein, M 1970, 'A Comparison of Neural-Based Techniques Investigating Rotational Invariance for Upright People Detection in Low Resolution Imagery', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Springer Berlin Heidelberg, pp. 647-653.
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This paper describes a neural-based technique for detecting upright persons in low-resolution beach imagery in order to predict trends of tourist activities at beach sites. The proposed system uses a structural feature extraction technique to represent objects of interest for training a selection of neural classifiers. A number of neural-based classifiers are compared in this study and a direction-based feature extraction technique is investigated in conjunction with a rotationally invariant procedure for the purpose of beach object classification. Encouraging results are presented for person detection using video imagery collected from a beach site on the coast of Australia. © Springer-Verlag Berlin Heidelberg 2007.
Hoyer, P, Lee, T & Spalek, R 1970, 'Negative weights make adversaries stronger', Proceedings of the thirty-ninth annual ACM symposium on Theory of computing, STOC07: Symposium on Theory of Computing, ACM.
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Li, S 1970, 'Combining topological and directional information for spatial reasoning', IJCAI International Joint Conference on Artificial Intelligence, International Joint Conference on Artificial Intelligence, AAAI Press, Hyderabad, India, pp. 435-440.
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Current research on qualitative spatial representation and reasoning usually focuses on one single aspect of space. However, in real world applications, several aspects are often involved together. This paper extends the well-known RCC8 constraint language to deal with both topological and directional information, and then investigates the interaction between the two kinds of information. Given a topological (RCC8) constraint network and a directional constraint network, we ask when the joint network is satisfiable. We show that when the topological network is over one of the three maximal tractable subclasses of RCC8, the problem can be reduced into satisfiability problems in the RCC8 algebra and the rectangle algebra (RA). Therefore, reasoning techniques developed for RCC8 and RA can be used to solve the satisfiability problem of a joint network.
Nguyen, V, Blumenstein, M, Muthukkumarasamy, V & Leedharn, G 1970, 'Off-line signature verification using enhanced modified direction features in conjunction with neural classifiers and support vector machines', ICDAR 2007: NINTH INTERNATIONAL CONFERENCE ON DOCUMENT ANALYSIS AND RECOGNITION, VOLS I AND II, PROCEEDINGS, 9th International Conference on Document Analysis and Recognition, IEEE COMPUTER SOC, Curitiba, BRAZIL, pp. 734-738.
Witzigmann, B, Steiger, S, Tomamichel, M, Veprek, R & Schwarz, UT 1970, 'Optical gain in 407nm and 470nm InGaN/GaN heterostructures: signature of quantum-dot states', Optoelectronic Materials and Devices II, Asia-Pacific Optical Communications, SPIE, Wuhan, PEOPLES R CHINA.
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Xia, L, Lang, J & Ying, M 1970, 'Sequential voting rules and multiple elections paradoxes.', TARK, pp. 279-288.
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Multiple election paradoxes arise when voting separately on each issue from a set of related issues results in an obviously undesirable outcome. Several authors have argued that a sufficient condition for avoiding multiple election paradoxes is the assumption that voters have separable preferences. We show that this extremely demanding restriction can be relaxed into the much more reasonable one: there exists a linear order x1 > ... > x p on the set of issues such that for each voter, every issue x i is preferentially independent of xi+1, ..., x p given x1, ..., xi-1. This leads us to define a family of sequential voting rules, defined as the sequential composition of local voting rules. These rules relate to the setting of conditional preference networks (CP-nets) recently developed in the Artificial Intelligence literature. We study in detail how these sequential rules inherit, or do not inherit, the properties of their local components. We focus on the case of multiple referenda, corresponding to multiple elections with binary issues.
Xia, L, Lang, J & Ying, M 1970, 'Strongly Decomposable Voting Rules on Multiattribute Domains.', AAAI, AAAI Press, pp. 776-781.
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Sequential composition of voting rules, by making use of structural properties of the voters' preferences, provide computationally economical ways for making a common decision over a Cartesian product of finite local domains. A sequential composition is usually defined on a set of legal profiles following a fixed order. In this paper, we generalize this by order-independent sequential composition and strong decomposable, which are independent of the chosen order. We study to which extent some usual properties of voting rules transfer from the local rules to their order-independent sequential composition. Then, to capture the idea that a voting rule is neutral or decomposable on a slightly smaller domain, we define nearly neutral, nearly decomposable rules for both sequential composition and order-independent sequential composition, which leads us to defining and studying decomposable permutations. We prove that any sequential composition of neutral local rules and any order-independent sequential composition of neutral local rules satisfying a necessary condition are nearly neutral. Copyright © 2007, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved.
