Tesis sobre el tema "Information theory"
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1
Hjørland, Birger. "Principia Informatica. Foundational Theory of Information and Principles of Information Services". Libraries Unlimited, 2002. http://hdl.handle.net/10150/105735.
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Library and information science (LIS) may alternatively be labeled library, information and documentation studies, LID or just information science, IS. In taking IS serious as a research field, this paper presents an understanding of one of its core concepts (information) and outlines its fundamental principles. It is shown that there exist hierarchies of information processing mechanisms in nature and culture and that IS is concerned with only the highest forms of such mechanisms, which consist of libraries, electronic databases and related information services. Theories about such high-level information systems are closely related to theoretical views of knowledge, language, documents, cognition, science and communication. Information scientists are not the only experts involved in the handling of information, and a view of our special role is presented. The aspiration of this article is to provide a synopsis of the fundamentals of IS: Principia Informatica.
2
Bond, Rachael Louise. "Relational information theory". Thesis, University of Sussex, 2018. http://sro.sussex.ac.uk/id/eprint/76664/.
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Sahai, Anant. "Anytime information theory". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8770.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 171-175).
We study the reliable communication of delay-sensitive bit streams through noisy channels. To bring the issues into sharp focus, we will focus on the specific problem of communicating the values of an unstable real-valued discrete-time Markov random process through a finite capacity noisy channel so as to have finite average squared error from end-to-end. On the source side, we give a coding theorem for such unstable processes that shows that we can achieve the rate-distortion bound even in the infinite horizon case if we are willing to tolerate bounded delays in encoding and decoding. On the channel side, we define a new parametric notion of capacity called anytime capacity that corresponds to a sense of reliable transmission that is stronger than the traditional Shannon capacity sense but is less demanding than the sense underlying zero-error capacity. We show that anytime capacity exists for memoryless channels without feedback and is connected to standard random coding error exponents. The main result of the thesis is a new source/channel separation theorem that encompasses unstable processes and establishes that the stronger notion of anytime capacity is required to be able to deal with delay-sensitive bit streams. This theorem is then applied in the control systems context to show that anytime capacity is also required to evaluate channels if we intend to use them as part of a feedback link from sensing to actuation. Finally, the theorem is used to shed light on the concept of "quality of service requirements" by examining a toy mathematical example for which we prove the absolute necessity of differentiated service without appealing to human preferences.
by Anant Sahai.
Ph.D.
4
Schumann, Robert Helmut. "Quantum information theory". Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51892.
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Thesis (MSc)--Stellenbosch University, 2000ENGLISH ABSTRACT: What are the information processing capabilities of physical systems? As recently as the first half of the 20th century this question did not even have a definite meaning. What is information, and how would one process it? It took the development of theories of computing (in the 1930s) and information (late in the 1940s) for us to formulate mathematically what it means to compute or communicate. Yet these theories were abstract, based on axiomatic mathematics: what did physical systems have to do with these axioms? Rolf Landauer had the essential insight - "Information is physical" - that information is always encoded in the state of a physical system, whose dynamics on a microscopic level are well-described by quantum physics. This means that we cannot discuss information without discussing how it is represented, and how nature dictates it should behave. Wigner considered the situation from another perspective when he wrote about "the unreasonable effectiveness of mathematics in the natural sciences". Why are the computational techniques of mathematics so astonishingly useful in describing the physical world [1]? One might begin to suspect foul play in the universe's operating principles. Interesting insights into the physics of information accumulated through the 1970s and 1980s - most sensationally in the proposal for a "quantum computer". If we were to mark a particular year in which an explosion of interest took place in information physics, that year would have to be 1994, when Shor showed that a problem of practical interest (factorisation of integers) could be solved easily on a quantum computer. But the applications of information in physics - and vice versa - have been far more widespread than this popular discovery. These applications range from improved experimental technology, more sophisticated measurement techniques, methods for characterising the quantum/classical boundary, tools for quantum chaos, and deeper insight into quantum theory and nature. In this thesis I present a short review of ideas in quantum information theory. The first chapter contains introductory material, sketching the central ideas of probability and information theory. Quantum mechanics is presented at the level of advanced undergraduate knowledge, together with some useful tools for quantum mechanics of open systems. In the second chapter I outline how classical information is represented in quantum systems and what this means for agents trying to extract information from these systems. The final chapter presents a new resource: quantum information. This resource has some bewildering applications which have been discovered in the last ten years, and continually presents us with unexpected insights into quantum theory and the universe.
AFRIKAANSE OPSOMMING: Tot watter mate kan fisiese sisteme informasie verwerk? So onlangs soos die begin van die 20ste eeu was dié vraag nog betekenisloos. Wat is informasie, en wat bedoel ons as ons dit wil verwerk? Dit was eers met die ontwikkeling van die teorieë van berekening (in die 1930's) en informasie (in die laat 1940's) dat die tegnologie beskikbaar geword het wat ons toelaat om wiskundig te formuleer wat dit beteken om te bereken of te kommunikeer. Hierdie teorieë was egter abstrak en op aksiomatiese wiskunde gegrond - mens sou wel kon wonder wat fisiese sisteme met hierdie aksiomas te make het. Dit was Rolf Landauer wat uiteindelik die nodige insig verskaf het - "Informasie is fisies" - informasie word juis altyd in 'n fisiese toestand gekodeer, en so 'n fisiese toestand word op die mikroskopiese vlak akkuraat deur kwantumfisika beskryf. Dit beteken dat ons nie informasie kan bespreek sonder om ook na die fisiese voorstelling te verwys nie, of sonder om in ag te neem nie dat die natuur die gedrag van informasie voorskryf. Hierdie situasie is vanaf 'n ander perspektief ook deur Wigner beskou toe hy geskryf het oor "die onredelike doeltreffendheid van wiskunde in die natuurwetenskappe". Waarom slaag wiskundige strukture en tegnieke van wiskunde so uitstekend daarin om die fisiese wêreld te beskryf [1]? Dit laat 'n mens wonder of die beginsels waarvolgens die heelal inmekaar steek spesiaal so saamgeflans is om ons 'n rat voor die oë te draai. Die fisika van informasie het in die 1970's en 1980's heelwat interessante insigte opgelewer, waarvan die mees opspraakwekkende sekerlik die gedagte van 'n kwantumrekenaar is. As ons één jaar wil uitsonder as die begin van informasiefisika, is dit die jaar 1994 toe Shor ontdek het dat 'n belangrike probleem van algemene belang (die faktorisering van groot heelgetalle) moontlik gemaak word deur 'n kwantumrekenaar. Die toepassings van informasie in fisika, en andersom, strek egter veel wyer as hierdie sleutel toepassing. Ander toepassings strek van verbeterde eksperimentele metodes, deur gesofistikeerde meetmetodes, metodes vir die ondersoek en beskrywing van kwantumchaos tot by dieper insig in die samehang van kwantumteorie en die natuur. In hierdie tesis bied ek 'n kort oorsig oor die belangrikste idees van kwantuminformasie teorie. Die eerste hoofstuk bestaan uit inleidende materiaal oor die belangrikste idees van waarskynlikheidsteorie en klassieke informasie teorie. Kwantummeganika word op 'n gevorderde voorgraadse vlak ingevoer, saam met die nodige gereedskap van kwantummeganika vir oop stelsels. In die tweede hoofstuk spreek ek die voorstelling van klassieke informasie en kwantumstelsels aan, en die gepaardgaande moontlikhede vir 'n agent wat informasie uit sulke stelsels wil kry. Die laaste hoofstuk ontgin 'n nuwe hulpbron: kwantuminformasie. Gedurende die afgelope tien jaar het hierdie nuwe hulpbron tot verbysterende nuwe toepassings gelei en ons keer op keer tot onverwagte nuwe insigte oor kwantumteorie en die heelal gelei.
5
Huang, Shao-Lun Ph D. Massachusetts Institute of Technology. "Euclidean network information theory". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84888.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 121-123).
Many network information theory problems face the similar difficulty of single letterization. We argue that this is due to the lack of a geometric structure on the space of probability distributions. In this thesis, we develop such a structure by assuming that the distributions of interest are all close to each other. Under this assumption, the Kullback-Leibler (K-L) divergence is reduced to the squared Euclidean metric in an Euclidean space. In addition, we construct the notion of coordinate and inner product, which will facilitate solving communication problems. We will present the application of this approach to the point-to-point channels, general broadcast channels (BC), multiple access channels (MAC) with common sources, interference channels, and multi-hop layered communication networks without or with feedback. It can be shown that with this approach, information theory problems, such as the single-letterization, can be reduced to some linear algebra problems. Solving these linear algebra problems, we will show that for the general broadcast channels, transmitting the common message to receivers can be formulated as the trade-off between linear systems. We also provide an example to visualize this trade-off in a geometric way. For the MAC with common sources, we observe a coherent combining gain due to the cooperation between transmitters, and this gain can be obtained quantitively by applying our technique. In addition, the developments of the broadcast channels and multiple access channels suggest a trade-off relation between generating common messages for multiple users and transmitting them as the common sources to exploit the coherent combining gain, when optimizing the throughputs of communication networks. To study the structure of this trade-off and understand its role in optimizing the network throughput, we construct a deterministic model by our local approach that captures the critical channel parameters and well models the network. With this deterministic model, for multi-hop layered networks, we analyze the optimal network throughputs, and illustrate what kinds of common messages should be generated to achieve the optimal throughputs. Our results provide the insight of how users in a network should cooperate with each other to transmit information efficiently.
by Shao-Lun Huang.
Ph.D.
6
Faghfoor, Maghrebi Mohammad. "Information gain in quantum theory". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2724.
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In this thesis I address the fundamental question that how the information
gain is possible in the realm of quantum mechanics where a single measurement
alters the state of the system. I study an ensemble of particles in some unknown (but product) state in detail and suggest an optimal way of gaining the maximum information and also quantify the corresponding information exactly. We find a rather novel result which is quite different from other well-known definitions of the information gain in quantum theory.
7
Vedral, Vlatko. "Quantum information theory of entanglement". Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299786.
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Girolami, Davide. "Quantum correlations in information theory". Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13397/.
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The project concerned the study of quantum correlations (QC) in compound systems, i.e. statistical correlations more general than entanglement which are predicted by quantum mechanics but not described in any classical scenario. I aimed to understand the technical and operational properties of the measures of QC, their interplay with entanglement quantifiers and the experimental accessibility. In the first part of my research path, after having acquired the conceptual and technical rudiments of the project, I provided solutions for some computational issues: I developed analytical and numerical algorithms for calculating bipartite QC in finite dimensional systems. Then, I tackled the problem of the experimental detection of QC. There is no Hermitian operator associated with entanglement measures, nor with QC ones. However, the information encoded in a density matrix is redundant to quantify them, thus the full knowledge of the state is not required to accomplish the task. I reported the first protocol to measure the QC of an unknown state by means of a limited number of measurements, without performing the tomography of the state. My proposal has been implemented experimentally in a NMR (Nuclear Magnetic Resonance) setting. In the final stage of the project, I explored the foundational and operational merits of QC. I showed that the QC shared by two subsystems yield a genuinely quantum kind of uncertainty on single local observables. The result is a promising evidence of the potential exploitability of separable (unentangled) states for quantum metrology in noisy conditions.
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Hawes, Vanessa Lucey. "Music's experiment with information theory". Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.514351.
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Daemi, M. F. "Information theory and pattern recognition". Thesis, University of Nottingham, 1990. http://eprints.nottingham.ac.uk/14003/.
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This thesis presents an account of an investigation into the use of information theory measures in pattern recognition problems. The objectives were firstly to determine the information content of the set of representations of an input image which are found at the output of an array of sensors; secondly to assess the information which may be used to allocate different patterns to appropriate classes in order to provide a means of recognition; and thirdly to assess the recognition capability of pattern recognition systems and their efficiency of utilization of information. Information assessment techniques were developed using fundamental principles of information theory. These techniques were used to assess the information associated with attributes such as orientation and location, of a variety of input images. The techniques were extended to permit the assessment of recognition capability and to provide a measure of the efficiency with which pattern recognition systems use the information available.
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Butterley, Paul. "Topics in quantum information theory". Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444697.
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Svensson, Bolennarth. "Information theory in quality engineering". Thesis, University of Strathclyde, 1998. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=29903.
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This thesis presents the results of research into a universal theory for quality techniques. The unique contribution that is made is twofold: • A new quality metric is proposed; • An integrating perspective to quality engineering is introduced through the application of information theory. The quality metric is designed as an information distance, measuring the difference between two probability density functions. The two distributions are the actual outcome of a running process and the expected outcome, i.e. the target distribution. The target distribution makes it possible to integrate the quality losses into the metric. The metric may be adapted to the state of knowledge of the process studied. The new quality metric is applicable to any process, be it a product processor an administration process. The information distance metric makes the analysis procedures uniform for all types of quality characteristics. A function based process documentation makes information theory generally applicable to quality engineering. The function description makes it possible to visualize poor quality as a surplus of information. All quality techniques aim at minimizing the information content in the system. Quality engineering in general may be expressed as an activity to stop surplus information flow reaching the process result. There is a natural focus on noise, i.e. influencing factors that are out of control of the user, affecting the systems. This focus is in robust design developed through a process performance perspective rather than an experimental design perspective. An effort addressing a product process subject to improvement has to be discriminated from an effort addressing the efficiency of the experimentation process used to study the product process. The present work is of pioneering character. Thus it opens a new area of research. Areas of further research are indicated.
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Angelino, Cesario Vicenzo. "Information theory oriented image restauration". Nice, 2011. http://www.theses.fr/2011NICE4044.
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Cette thèse aborde la formulation par la théorie de l’information des problèmes de traitement d’image. Cette formulation exprime la solution au travers de la minimisation d’une énergie. Ces énergies appartiennent à la classe non paramétrique au sens où elles ne font aucune hypothèse paramétrique sur la distribution des données. Les énergies sont exprimées directement en fonction des données considérées comme des variables aléatoires. Toutefois, l’estimation non paramétrique classique repose sur des noyaux de taille fixe moins fiables lorsqu’il s’agit de données de grande dimension. En particulier, des méthodes récentes dans le traitement de l’image dépendent des données de type ”patch” correspondant à des vecteurs de description de modèles locaux des images naturelles, par exemple, les voisinages de pixels. Le cadre des k-plus proches voisins résout ces difficultés en s’adaptant localement à la distribution des données dans ces espaces de grande dimension. Sur la base de ces prémisses, nous développons de nouveaux algorithmes qui s’attaquent principalement à deux problèmes du traitement de l’image : la déconvolution et le débruitage. Le problème de la restauration est développé dans les hypothèses d’un bruit blanc gaussien additive puis successivement adaptés à domaines tels que la photographie numérique et le débruitage d’image radar (SAR). Le schéma du débruitage est également modifié pour définir un algorithme d’inpaintingThis thesis addresses informational formulation of image processing problems. This formulation expresses the solution through a minimization of an information-based energy. These energies belong to the nonparametric class in that they do not make any parametric assumption on the underlying data distribution. Energies are expressed directly as a function of the data considered as random variables. However, classical nonparametric estimation relies on fixed-size kernels which becomes less reliable when dealing with high dimensional data. Actually, recent trends in image processing rely on patch-based approaches which deal with vectors describing local patterns of natural images, e. G. , local pixel neighborhoods. The k-Nearest Neighbors framework solves these difficulties by locally adapting the data distribution in such high dimensional spaces. Based on these premises, we develop new algorithms tackling mainly two problems of image processing: deconvolution and denoising. The problem of denoising is developed in the additive white Gaussian noise (AWGN) hypothesis and successively adapted to no AWGN realm such as digital photography and SAR despeckling. The denoising scheme is also modified to propose an inpainting algorithm
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Abeyesinghe, Anura Yamesh Preskill John P. "Unification of quantum information theory /". Diss., Pasadena, Calif. : Caltech, 2006. http://resolver.caltech.edu/CaltechETD:etd-05252006-222551.
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Pachas, Erik W. "Probabilistic Methods In Information Theory". CSUSB ScholarWorks, 2016. https://scholarworks.lib.csusb.edu/etd/407.
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Given a probability space, we analyze the uncertainty, that is, the amount of information of a finite system, by studying the entropy of the system. We also extend the concept of entropy to a dynamical system by introducing a measure preserving transformation on a probability space. After showing some theorems and applications of entropy theory, we study the concept of ergodicity, which helps us to further analyze the information of the system.
16
Fukuda, Motohisa. "Additivity conjectures in quantum information theory". Thesis, University of Cambridge, 2007. https://www.repository.cam.ac.uk/handle/1810/252051.
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Lukits, Stefan Hermann. "Information theory and partial belief reasoning". Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58193.
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The dissertation investigates the nature of partial beliefs and norms governing their use. One widely accepted (though not uncontested) norm for partial belief change is Bayesian conditionalization. Information theory provides a far-reaching generalization of Bayesian conditionalization and gives it a foundation in an intuition that pays attention principally to information contained in probability distributions and information gained with new evidence. This generalization has fallen out of favour with contemporary epistemologists. They prefer an eclectic approach which sometimes conflicts with norms based on information theory, particularly the entropy principles of information theory. The principle of maximum entropy mandates a rational agent to hold minimally informative partial beliefs given certain background constraints; the principle of minimum cross-entropy mandates a rational agent to update partial beliefs at minimal information gain consistent with the new evidence. The dissertation shows that information theory generalizes Bayesian norms and does not conflict with them. It also shows that the norms of information theory can only be defended when the agent entertains sharp credences. Many contemporary Bayesians permit indeterminate credal states for rational agents, which is incompatible with the norms of information theory. The dissertation then defends two claims: (1) the partial beliefs that a rational agent holds are formally expressed by sharp credences; and (2) when a rational agent updates these partial beliefs in the light of new evidence, the norms used are based on and in agreement with information theory. In the dissertation, I defuse a collection of counter-examples that have been marshaled against entropy principles. More importantly, building on previous work by others and expanding it, I provide a coherent and comprehensive theory of the use of information theory in formal epistemology. Information theory rivals probability theory in formal virtue, theoretical substance, and coherence across intuitions and case studies. My dissertation demonstrates its significance in explaining the doxastic states of a rational agent and in providing the right kind of normativity for them.Arts, Faculty of
Philosophy, Department of
Graduate
18
Karvovskaya, Lena, Vadim Kimmelman, Christine Tanja Röhr, Pepi Stavropoulou, Elena Titov y Putten Saskia van. "Information structure : empirical perspectives on theory". Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2013/6480/.
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The papers collected in this volume were presented at a Graduate/Postgraduate Student Conference with the title Information Structure: Empirical Perspectives on Theory held on December 2 and 3, 2011 at Potsdam-Griebnitzsee. The main goal of the conference was to connect young researchers working on information structure (IS) related topics and to discuss various IS categories such as givenness, focus, topic, and contrast. The aim of the conference was to find at least partial answers to the following questions: What IS categories are necessary? Are they gradient/continuous? How can one deal with optionality or redundancy? How are IS categories encoded grammatically? How do different empirical methods contribute to distinguishing between the influence of different IS categories on language comprehension and production? To answer these questions, a range of languages (Avatime, Chinese, German, Ishkashimi, Modern Greek, Old Saxon, Russian, Russian Sign Language and Sign Language of the Netherlands) and a range of phenomena from phonology, semantics, and syntax were investigated. The presented theories and data were based on different kinds of linguistic evidence: syntactic and semantic fieldwork, corpus studies, and phonological experiments. The six papers presented in this volume discuss a variety of IS categories, such as emphasis and contrast (Stavropoulous, Titov), association with focus and topics (van Putten, Karvovskaya), and givenness and backgrounding (Kimmelmann, Röhr).
19
Buchanan, Steven. "The information audit: theory versus practice". Thesis, University of Strathclyde, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488844.
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The information audit (lA) provides a method to identify, evaluate, and manage an organisation's information resources. With such a central information management role, it might be reasonable to assume that the lA would be an accepted element of information management best practice, particularly given the growth of information based services, and growing recognition of information as a primary resource and tradable commodity.
20
Maroney, Owen Jack Ernest. "Information and entropy in quantum theory". Thesis, Birkbeck (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268835.
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Recent developments in quantum computing have revived interest in the notion of information as a foundational principle in physics. It has been suggested that information provides a means of interpreting quantum theory and a means of understanding the role of entropy in thermodynamics. The thesis presents a critical examination of these ideas, and contrasts the use of Shannon information with the concept of 'active information' introduced by Bohm and Hiley. We look at certain thought experiments based upon the 'delayed choice' and 'quantum eraser' interference experiments, which present a complementarity between information gathered from a quantum measurement and interference effects. It has been argued that these experiments show the Bohm interpretation of quantum theory is untenable. We demonstrate that these experiments depend critically upon the assumption that a quantum optics device can operate as a measuring device, and show that, in the context of these experiments, it cannot be consistently understood in this way. By contrast, we then show how the notion of 'active information' in the Bohm interpretation provides a coherent explanation of the phenomena shown in these experiments. We then examine the relationship between information and entropy. The thought experiment connecting these two quantities is the Szilard Engine version of Maxwell's Demon, and it has been suggested that quantum measurement plays a key role in this. We provide the first complete description of the operation of the Szilard Engine as a quantum system. This enables us to demonstrate that the role of quantum measurement suggested is incorrect, and further, that the use of information theory to resolve Szilard's paradox is both unnecessary and insufficient. Finally we show that, if the concept of 'active information' is extended to cover thermal density matrices, then many of the conceptual problems raised by this paradox appear to be resolved.
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Sørngård, Bård. "Information Theory for Analyzing Neural Networks". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26773.
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The goal of this thesis was to investigate how information theory could be used to analyze artificial neural networks. For this purpose, two problems, a classification problem and a controller problem were considered. The classification problem was solved with a feedforward neural network trained with backpropagation, the controller problem was solved with a continuous-time recurrent neural network optimized with evolution.Results from the classification problem shows that mutual information might indicate how much a particular neuron contributes to the classification. Tracking these neurons' mutual information during training might serve as an indicator of their progression, including neurons in the hidden layers.Results from the controller problem showed that time-delayed mutual information between a neuron and an environment variable might indicate what variable each neuron is estimating, and tracking this during evolution might tell us when this particular neuron started taking this role. Furthermore, unrolled transfer entropy appears to be a good measure for how neurons affect each other during simulation.
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Schein, Brett E. (Brett Eric). "Distributed coordination in network information theory". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/16786.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.Includes bibliographical references (p. 227-231).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Constructing a large-scale wireless data network is spectacularly expensive. It is therefore important to understand how to efficiently utilize the physical infrastructure and available battery power, which are expensive system resources. Unfortunately, we currently understand very little about efficient communication in a distributed environment. In distributed wireless networks, there appears to be an interesting and complex trade-off between trying to take advantage of independent noisy signals at different relays and closely coordinating relay transmissions to a receiver. Designing the right structure for efficient communication, by choice of source transmission codebook and relay terminal processing, is the important and difficult problem on which we focus. We use an information theoretic framework to study several very simple multiple terminal networks, focusing exclusively on single source, single destination networks where communication must take place through intermediate nodes. Our goal is to determine how much data we can get reliably from source to destination, placing no importance on delay or computational complexity. The core problem then involves distributed detection at the intermediate nodes and coordination in relaying information to the destination.
by Brett E. Schein.
Ph.D.
23
Meznaric, Sebastian. "Information theoretic resources in quantum theory". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:ac3a801c-6351-4882-b6ed-5b2f635cff45.
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Resource identification and quantification is an essential element of both classical and quantum information theory. Entanglement is one of these resources, arising when quantum communication and nonlocal operations are expensive to perform. In the first part of this thesis we quantify the effective entanglement when operations are additionally restricted to account for both fundamental restrictions on operations, such as those arising from superselection rules, as well as experimental errors arising from the imperfections in the apparatus. For an important class of errors we find a linear relationship between the usual and effective higher dimensional generalization of concurrence, a measure of entanglement. Following the treatment of effective entanglement, we focus on a related concept of nonlocality in the presence of superselection rules (SSR). Here we propose a scheme that may be used to activate nongenuinely multipartite nonlocality, in that a single copy of a state is not multipartite nonlocal, while two or more copies exhibit nongenuinely multipartite nonlocality. The states used exhibit the more powerful genuinely multipartite nonlocality when SSR are not enforced, but not when they are, raising the question of what is needed for genuinely multipartite nonlocality. We show that whenever the number of particles is insufficient, the degrading of genuinely multipartite to nongenuinely multipartite nonlocality is necessary. While in the first few chapters we focus our attention on understanding the resources present in quantum states, in the final part we turn the picture around and instead treat operations themselves as a resource. We provide our observers with free access to classical operations - ie. those that cannot detect or generate quantum coherence. We show that the operation of interest can then be used to either generate or detect quantum coherence if and only if it violates a particular commutation relation. Using the relative entropy, the commutation relation provides us with a measure of nonclassicality of operations. We show that the measure is a sum of two contributions, the generating power and the distinguishing power, each of which is separately an essential ingredient in quantum communication and information processing. The measure also sheds light on the operational meaning of quantum discord - we show it can be interpreted as the difference in superdense coding capacity between a quantum state and a classical state.
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Jenkinson, Justin. "Convex Geometric Connections to Information Theory". Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1365179413.
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Benešová, Anita. "Job Information Networks and Game Theory". Master's thesis, Vysoká škola ekonomická v Praze, 2010. http://www.nusl.cz/ntk/nusl-81886.
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The use of personal contacts and the role of education as a signal of the Worker's productivity are two important aspects of the job search process. The aim of this thesis is to develop a model that combines both approaches. We distinguish between random and strategic models of job information networks. In the former case the structure of the network is given, while in the latter it depends on the strategic decision of the Workers. We present a strategic model of network formation with two types of Workers who are able to signal their productivity by the level of their education. When applying for a job they have two possibilities of contacting the Employer: a direct application and an indirect application through a friend who currently works for the Employer.
26
Chli, Margarita. "Applying information theory to efficient SLAM". Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5634.
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The problem of autonomous navigation of a mobile device is at the heart of the more general issue of spatial awareness and is now a well-studied problem in the robotics community. Following a plethora of approaches throughout the history of this research, recently, implementations have been converging towards vision-based methods. While the primary reason for this success is the enormous amount of information content encrypted in images, this is also the main obstacle in achieving faster and better solutions. The growing demand for high-performance systems able to run on affordable hardware pushes algorithms to the limits, imposing the need for more effective approximations within the estimation process. The biggest challenge lies in achieving a balance between two competing goals: the optimisation of time complexity and the preservation of the desired precision levels. The key is in agile manipulation of data, which is the main idea explored in this thesis. Exploiting the power of probabilistic priors in sequential tracking, we conduct a theoretical investigation of the information encoded in measurements and estimates, which provides a deep understanding of the map structure as perceived through the camera lens. Employing information theoretic principles to guide the decisions made throughout the estimation process we demonstrate how this methodology can boost both the efficiency and consistency of algorithms. Focusing on the most challenging processes in a state of the art system, we apply our information theoretic framework to local motion estimation and maintenance of large probabilistic maps. Our investigation gives rise to dynamic algorithms for quality map-partitioning and robust feature mapping in the presence of significant ambiguity and variable camera dynamics. The latter is further explored to achieve scalable performance allowing dense feature matching based on concrete probabilistic decisions.
27
Han, Lin. "Graph generative models from information theory". Thesis, University of York, 2012. http://etheses.whiterose.ac.uk/3726/.
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Generative models are commonly used in statistical pattern recognition to describe the probability distributions of patterns in a vector space. In recent years, sustained by the wide range of mathematical tools available in vector space, many algorithms for constructing generative models have been developed. Compared with the advanced development of the generative model for vectors, the development of a generative model for graphs has had less progress. In this thesis, we aim to solve the problem of constructing the generative model for graphs using information theory. Given a set of sample graphs, the generative model for the graphs we aim to construct should be able to not only capture the structural variation of the sample graphs, but to also allow new graphs which share similar properties with the original graphs to be generated. In this thesis, we pose the problem of constructing a generative model for graphs as that of constructing a supergraph structure for the graphs. In Chapter 3, we describe a method of constructing a supergraph-based generative model given a set of sample graphs. By adopting the a posteriori probability developed in a graph matching problem, we obtain a probabilistic framework which measures the likelihood of the sample graphs, given the structure of the supergraph and the correspondence information between the nodes of the sample graphs and those of the supergraph. The supergraph we aim to obtain is one which maximizes the likelihood of the sample graphs. The supergraph is represented here by its adjacency matrix, and we develop a variant of the EM algorithm to locate the adjacency matrix that maximizes the likelihood of the sample graphs. Experimental evaluations demonstrate that the constructed supergraph performs well on classifying graphs. In Chapter 4, we aim to develop graph characterizations that can be used to measure the complexity of graphs. The first graph characterization developed is the von Neumann entropy of a graph associated with its normalized Laplacian matrix. This graph characterization is defined by the eigenvalues of the normalized Laplacian matrix, therefore it is a member of the graph invariant characterization. By applying some transformations, we also develop a simplified form of the von Neumann entropy, which can be expressed in terms of the node degree statistics of the graphs. Experimental results reveal that effectiveness of the two graph characterizations. Our third contribution is presented in Chapter 5, where we use the graph characterization developed in Chapter 4 to measure the supergraph complexity and we develop a novel framework for learning a supergraph using the minimum description length criterion. We combine the Jensen-Shanon kernel with our supergraph construction and this provides us with a way of measuring graph similarity. Moreover, we also develop a method of sampling new graphs from the supergraph. The supergraph we present in this chapter is a generative model which can fulfil the tasks of graph classification, graph clustering, and of generating new graphs. We experiment with both the COIL and “Toy” datasets to illustrate the utility of our generative model. Finally, in Chapter 6, we propose a method of selecting prototype graphs of the most appropriate size from candidate prototypes. The method works by partitioning the sample graphs into two parts and approximating their hypothesis space using the partition functions. From the partition functions, the mutual information between the two sets is defined. The prototype which gives the highest mutual information is selected.
28
Fallis, Don. "Epistemic Value Theory and Information Ethics". Springer, 2004. http://hdl.handle.net/10150/105254.
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Three of the major issues in information ethics—intellectual property, speech regulation, and privacy—concern the morality of restricting people’s access to certain information. Consequently, policies in these areas have a significant impact on the amount and types of knowledge that people acquire. As a result, epistemic considerations are critical to the ethics of information policy decisions (cf. Mill 1978 [1859]). The fact that information ethics is a part of the philosophy of information highlights this important connection with epistemology. In this paper, I illustrate how a value-theoretic approach to epistemology can help to clarify these major issues in information ethics. However, I also identify several open questions about epistemic values that need to be answered before we will be able to evaluate the epistemic consequences of many information policies.
29
Bonev, Boyan. "Feature selection based on information theory". Doctoral thesis, Universidad de Alicante, 2010. http://hdl.handle.net/10045/18362.
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Along with the improvement of data acquisition techniques and the increasing computational capacity of computers, the dimensionality of the data grows higher. Pattern recognition methods have to deal with samples consisting of thousands of features and the reduction of their dimensionality becomes crucial to make them tractable. Feature selection is a technique for removing the irrelevant and noisy features and selecting a subset of features which describe better the samples and produce a better classification performance. It is becoming an essential part of most pattern recognition applications.In this thesis we propose a feature selection method for supervised classification. The main contribution is the efficient use of information theory, which provides a solid theoretical framework for measuring the relation between the classes and the features. Mutual information is considered to be the best measure for such purpose. Traditionally it has been measured for ranking single features without taking into account the entire set of selected features. This is due to the computational complexity involved in estimating the mutual information. However, in most data sets the features are not independent and their combination provides much more information about the class, than the sum of their individual prediction power.
Methods based on density estimation can only be used for data sets with a very high number of samples and low number of features. Due to the curse of dimensionality, in a multi-dimensional feature space the amount of samples required for a reliable density estimation is very high. For this reason we analyse the use of different estimation methods which bypass the density estimation and estimate entropy directly from the set of samples. These methods allow us to efficiently evaluate sets of thousands of features.
For high-dimensional feature sets another problem is the search order of the feature space. All non-prohibitive computational cost algorithms search for a sub-optimal feature set. Greedy algorithms are the fastest and are the ones which incur less overfitting. We show that from the information theoretical perspective, a greedy backward selection algorithm conserves the amount of mutual information, even though the feature set is not the minimal one.
We also validate our method in several real-world applications. We apply feature selection to omnidirectional image classification through a novel approach. It is appearance-based and we select features from a bank of filters applied to different parts of the image. The context of the task is place recognition for mobile robotics. Another set of experiments are performed on microarrays from gene expression databases. The classification problem aims to predict the disease of a new patient. We present a comparison of the classification performance and the algorithms we present showed to outperform the existing ones. Finally, we succesfully apply feature selection to spectral graph classification. All the features we use are for unattributed graphs, which constitutes a contribution to the field. We also draw interesting conclusions about which spectral features matter most, under different experimental conditions. In the context of graph classification we also show important is the precise estimation of mutual information and we analyse its impact on the final classification results.
30
Culpepper, Sarah Elizabeth. "Musical time and information theory entropy". Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/659.
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Many theorists have connected information content in music with the listener's perception of the passage of time. This thesis uses the construct of information theory entropy, developed in the 1940s by Bell Labs engineer Claude Shannon, to describe the passage of time in Webern's music. Entropy scores are computed based on pitches, intervals, CSEGs, and pc-sets; these scores are then used to examine the first of the Five Canons, op. 16, and the fourth of the Five Movements for String Quartet, op. 5.
31
Law, Yan Tai. "Pricing under random information flow and the theory of information pricing". Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9292.
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This thesis presents a mathematical formulation of informational inhomogeneity in financial markets, with emphasis on its impact on asset volatility, the notion of information extraction, and the role of information providers. We begin with a brief review of the BHM framework, which models the market filtration by an information process consisting of a signal and a noise term, such that the signal-to-noise ratio is determined by the information flow rate. Motivated by the observations that valuable information is rarely circulated homogeneously across financial markets, and that the information flow rate is typically random, we introduce, in the first part of the thesis, an extension of the BHM approach that leads to the simplest class of stochastic volatility models. In this extended framework we derive closed form expressions: for (a) asset price processes; (b) pricing formulae for options; and (c) option deltas. We show that the model can be calibrated to fit volatility surfaces reasonably well, and that it can be used effectively to model information manipulation. In the second part we introduce a framework for the valuation of information. In particular, a new formulation of the utility-indifference argument is introduced and used as a basis for pricing. We regard information as a quantity that converts a prior distributions into a posterior distributions. The amount of information can thus be quantified by relative entropy. The key to our theory is to equate the maximised a posterior utility with the a posterior expectation of the utility of the a priori optimal strategy. This formulation leads to one price for a given quantity of upside, and another for a given quantity of downside information. Various intuitive, as well as counterintuitive implications (for example, price of information is not necessarily an increasing function of the volume of information) of our theory are discussed in detail.
32
Sadok, Djamel Fawzi Hadj. "Interpersonal interchange of multimedia information". Thesis, University of Kent, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278242.
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Esmer, Ozcan. "Information Theory, Entropy And Urban Spatial Structure". Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606319/index.pdf.
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Urban planning has witnessed the profound changes in the methodologies of modelling during the last 50 years. Spatial interaction models have passed from social physics, statistical mechanics to non-spatial and spatial information processing stages of progress that can be designated as paradigm shifts.
This thesis traces the Maximum Entropy (MaxEnt) approach in urban planning as pioneered by Wilson (1967,1970) and Spatial Entropy concept by Batty (1974) based on the Information Theory and its developments by Shannon (1948), Jaynes (1957), Kullback (1959) and by Tribus (1962,1969).
Information-theoric methods have provided the theoretical foundation for challenging the uncertainty and incomplete information issues concerning the complex urban structure. MaxEnt, as a new logic, gives probabilities maximally noncommittal with regard to missing information. Wilson (1967,1970) has replaced the Newtonian analogy by the entropy concept from statistical mechanics to alleviate the mathematical inconsistency in the gravity model and developed a set of spatial interaction models consistent with the known information.
Population density distribution as one of the determinants of the urban structure has been regarded as an exemplar to show the paradigm changes from the analysis of density gradients to the probabilistic description of density distributions by information-theoric methods.
Spatial Entropy concept has introduced the spatial dimension to the Information Theory. Thesis applies Spatial Entropy measures to Ankara 1970 and 1990 census data by 34 zones and also obtains Kullback&rsquos Information Gain measures for population changes during the two decades. Empirical findings for Spatial Entropy measures show that overall Ankara-1970 and 1990 density distributions are &lsquo
&rsquo
Uneven&rsquo
&rsquo
and the uniform distribution hypothesis is not confirmed. These measures also indicate a tendency towards &ldquo
More Uniformity&rdquo
for density distributions in comparison to 1970. Information Gain measure for population changes also deviates from zero and direct proportionality hypothesis between posterior 1990 and prior 1970 population distributions by zones is not confirmed. Current research is focused on information processing with more engagement in the urban spatial structure and human behavior. This thesis aims to participate with these efforts and concludes that Information Theory has the potential to generate new profound changes in urban planning and modelling processes.
34
Puhakainen, P. (Petri). "A design theory for information security awareness". Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:9514281144.
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Abstract
When implementing their information security solutions organizations have typically focused on technical and procedural security measures. However, from the information systems (IS) point of view, this is not enough: effective IS security requires that users are aware of and use the available security measures as described in their organizations' information security policies and instructions. Otherwise, the usefulness of the security measures is lost.
The research question of this thesis is to explore how IS users' compliance with IS security policies and instructions can be improved. Solving this research question is divided into two steps. Since there is a lack of a comprehensive review of existing IS security awareness approaches, the first step aims at reviewing the existing IS security awareness approaches. This kind of analysis is useful for practitioners as they do not necessarily have the time to go through a large body of literature. For scholars, such an analysis shows what areas of IS security awareness have been studied, and to where the need for future research is of greatest importance.
The second step in this dissertation is to address the shortcomings detected by the analysis by developing three novel design theories for improving IS users' security behavior: (1) IS security awareness training, (2) IS security awareness campaigns, and (3) punishment and reward. These design theories aim to help practitioners to develop their own IS security awareness approaches. Finally, testing of the design theory for IS security awareness training (1) in two action research interventions is described. The results of the interventions suggest that this design theory provides a useful and applicable means for developing a training program in organizations. In addition, the results provide empirically evaluated information regarding the obstacles to user compliance with IS security policies and instructions.
In the action research studies described, the goal was to solve practical problems experienced by the host organizations and to understand them and the results achieved from the viewpoint of theory. Consequently, the results as such can not be generalized, but they are of use in the host organizations in planning and delivering subsequent IS security awareness training programs. In addition, the results are utilizable in similar organizations as a point of departure in planning IS security awareness training programs.
35
Seabrooke, Kevin Christopher. "Multimodal brain volume registration using information theory". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ56364.pdf.
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Savov, Ivan. "Network information theory for classical-quantum channels". Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110349.
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Network information theory is the study of communication problems involving multiple senders, multiple receivers and intermediate relay stations. The purpose of this thesis is to extend the main ideas of classical network information theory to the study of classical-quantum channels. We prove coding theorems for the following communication problems: quantum multiple access channels, quantum interference channels, quantum broadcast channels and quantum relay channels. A quantum model for a communication channel describes more accurately the channel's ability to transmit information. By using physically faithful models for the channel outputs and the detection procedure, we obtain better communication rates than would be possible using a classical strategy. In this thesis, we are interested in the transmission of classical information, so we restrict our attention to the study of classical-quantum channels. These are channels with classical inputs and quantum outputs, and so the coding theorems we present will use classical encoding and quantum decoding.We study the asymptotic regime where many copies of the channel are used in parallel, and the uses are assumed to be independent. In this context, we can exploit information-theoretic techniques to calculate the maximum rates for error-free communication for any channel, given the statistics of the noise on that channel. These theoretical bounds can be used as a benchmark to evaluate the rates achieved by practical communication protocols. Most of the results in this thesis consider classical-quantum channels with finite dimensional output systems, which are analogous to classical discrete memoryless channels. In the last chapter, we will show some applications of our results to a practical optical communication scenario, in which the information is encoded in continuous quantum degrees of freedom, which are analogous to classical channels with Gaussian noise.La théorie de l'information multipartite étudie les problèmes de communication avec plusieurs émetteurs, plusieurs récepteurs et des stations relais. L'objectif de cette thèse est d'étendre les idées centrales de la théorie de l'information classique à l'étude des canaux quantiques. Nous allons nous intéresser aux scénarios de communication suivants: les canaux quantiques à accès multiples, les canaux quantiques à interférence, les canaux quantiques de diffusion et les canaux quantiques à relais. Dans chacun des ces scénarios de communication, nous caractérisons les taux de communication réalisables pour l'envoi d'information classique sur ces canaux quantiques. La modélisation quantique des canaux de communication est importante car elle fournit une représentation plus précise de la capacité du canal à transmettre l'information. En utilisant des modèles physiquement réalistes pour les sorties du canal et la procédure de détection, nous obtenons de meilleurs taux de communication que ceux obtenus dans un modèle classique. En effet, l'utilisation de mesures quantiques collectives sur l'ensemble des systèmes physiques en sortie du canal permet une meilleure extraction d'information que des mesures indépendantes sur chaque sous-système. Nous avons choisi d'étudier les canaux à entrée classique et sortie quantique qui constituent une abstraction utile pour l'étude de canaux quantiques généraux où l'encodage est restreint au domaine classique.Nous étudions le régime asymptotique où de nombreuses copies de du canal sont utilisées en parallèle, et les utilisations sont indépendantes. Dans ce contexte, il est possible de caractériser les limites absolues sur la transmission d'information d'un canal, si on connait les statistiques du bruit sur ce canal. Ces résultats théoriques peuvent être utilisées comme un point de repère pour évaluer la performance des protocoles de communication pratiques. Nous considérons surtout les canaux où les sorties sont des systèmes quantiques de dimension finie, analogues aux canaux classiques discrets. Le dernier chapitre présente des applications pratiques de nos résultats à la communication optique, où systèmes physiques auront des degrés de liberté continus. Ce contexte est analogue aux canaux classiques avec bruit gaussien.
37
Quinn, Kathleen Anne Sara. "Combinatorial structures with applications to information theory". Thesis, Royal Holloway, University of London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261791.
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Barrett, J. "Entanglement, non-locality and quantum information theory". Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596412.
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In this dissertation, motivated both by our incomplete physical understanding, and by quantum information theory, we investigate quantum non-locality. In Chapter 2, we ask the question, which quantum states are non-local? We show that any entangled pure state is non-local, but that things are complicated with mixed states. In particular, following Werner’s local hidden variable model for projective measurements on a class of entangled states, we write down an extended model that works for arbitrary positive operator valued measurements performed by the separated observers. We also show that the existence of such a model for one particular quantum state implies the existence of a similar model for a wide class of other quantum states. Finally, we discuss the fact that some quantum states display a hidden non-locality, and describe a general classification scheme for the non-locality of quantum states. In Chapter 3, we turn to a particular protocol of quantum information theory, namely, quantum teleportation. We discuss the connections between quantum teleportation and non-locality. We drive a Bell-type inequality pertaining to the teleportation scenario and investigate when it is violated. We give an example of a situation in which a teleportation fidelity of ¾ is achieved without non-locality, even though this is greater than the classical limit of 2/3. In Chapter 4, we describe the experiments that have been performed as tests of quantum non-locality and the associated loopholes. We point out an assumption, the no-memory assumption that is common to nearly all analyses of Bell-type experiments, yet is not implied by locality. We remove the assumption and give a new analysis of the ideal case.
39
Richardson, Sandra. "HEALTHCARE INFORMATION SYSTEMS:DESIGN THEORY, PRINCIPLES AND APPLICATION". Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3182.
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Healthcare information systems (HISs), as a class of systems, are not currently addressed in the MIS literature. This is in spite of a sharp increase in use over the past few years, and the uniquely qualified role that MIS has in the development of, impact and general understanding of HISs. In this project the design science paradigm frames the development of a set of design principles derived from the synthesis of the design literature, ethics literature, and professional guidelines, from both the medical and computing professions. The resulting principles are offered to address the design of healthcare information systems. Action research, a widely accepted methodology for testing design principles derived from the design science paradigm, is employed to test the HIS principles and to implement change in a healthcare organization through the use of an HIS. The action research project was a collaborative effort between a Central Florida hospice and the researcher, the result of which was an advanced directives decision support system. The system was design to meet a number of organizational goals that ranged from tracking compliance with federal regulations to increasing the autonomy of the patients that used the system. The result is a set of tested design principles and lessons learned from both anticipated and unanticipated consequences of the action research project.Ph.D.
Department of Management Information Systems
Business Administration
Business Administration: Ph.D.
40
Selig, Marco. "Information theory based high energy photon imaging". Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-178899.
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Goyal, Philip. "An information-theoretic approach to quantum theory". Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614984.
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Kojima, Naoki. "Essays on economic theory in asymmetric information". Toulouse 1, 2001. http://www.theses.fr/2001TOU10093.
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Cette thèse traite trois sujets différents de l'aspect de l'asymétrie de l'information, plus particulièrement de la sélection adverse : étude de la "relationship banking" dans le cadre de concurrence entre banques ; introduction des actions d'une entreprise en bourse (conflits d'intérêt entre la firme émettrice, l'entreprise financière chargée de la mise en vente et les investisseurs) ; mécanisme de la tarification optimale d'un monopole avec des consommateurs contraints en budget et proposition d'une nouvelle approche de ce problème de l'asymétrie d'information bidimensionnelleThis thesis deals with three different subject matters from the aspect of asymmetric information, especially adverse selection: relationship banking in the framework of competition amongst banks ; initial public offering (conflicts of interests between the issuer, the underwriter and investors) ; mechanism of optimal pricing by a monopolistic seller in the presence of budget constraints on the part of buyers and proposition of new approach to this bi-dimensional asymmetric information problem
43
Smith, Charles Eldon. "An information-processing theory of party identification /". The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487848531364663.
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Dunleavy, Andrew J. "Applying information theory to super-cooled liquids". Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683695.
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In this thesis we study super-cooled liquids through simulations of hard interacting particles: hard disks in two dimensions, and hard spheres in three dimensions. These systems provide simple models of glass-forming liquids in general and are good models for colloidal glass-forming systems specifically. Whether static structure exists, and the nature of any collective motion are two key questions about super-cooled liquids. Both involve correlation, and this motivates us to use information theory: we use Shannon entropy and mutual information to provide general, unbiased measurements of disorder and correlation. We use mutual information to define an order agnostic order parameter in ther hard disk system and show that static correlations are short-ranged in these simulations. Many of the simulations described in this thesis are performed in the isoconfigurational ensemble. This technique gives access to probability distributions of particle trajectories conditioned on the initial system configuration. By using information theory to investigate these distributions we are able to answer questions about predictability in quantitative terms. We measure the predictability of the dynamics of our hard sphere system; then, by classifying the structure of the initial configuration, we search for the salient features that have predictive power over the dynamics. We find that classifying the initial configuration in terms of geometrical motifs and local volume fraction gives some predictive power. By using information theory to quantify dynamic correlations between particles we show that this predictivity exists because the initial configuration specifies the positions of early-relaxing particles and slow-relaxing relatively stable regions. Most particles belong to neither of these regions and are presumably responsible for the unpredictable behaviour of the system. The final results chapter in this thesis measures changes in shape of the dynamical regions in our model systems using fractal dimension.
45
Smith, Julian P. "Neural networks, information theory and knowledge representation". Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/20801.
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Borsten, Leron. "Aspects of M-theory and quantum information". Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6051.
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As the frontiers of physics steadily progress into the 21st century we should bear in mind that the conceptual edifice of 20th-century physics has at its foundations two mutually incompatible theories; quantum mechanics and Einstein’s general theory of relativity. While general relativity refuses to succumb to quantum rule, black holes are raising quandaries that strike at the very heart of quantum theory. M-theory is a compelling candidate theory of quantum gravity. Living in eleven dimensions it encompasses and connects the five possible 10-dimensional superstring theories. However, Mtheory is fundamentally non-perturbative and consequently remains largely mysterious, offering up only disparate corners of its full structure. The physics of black holes has occupied centre stage in uncovering its non-perturbative structure. The dawn of the 21st-century has also played witness to the birth of the information age and with it the world of quantum information science. At its heart lies the phenomenon of quantum entanglement. Entanglement has applications in the emerging technologies of quantum computing and quantum cryptography, and has been used to realize quantum teleportation experimentally. The longest standing open problem in quantum information is the proper characterisation of multipartite entanglement. It is of utmost importance from both a foundational and a technological perspective. In 2006 the entropy formula for a particular 8-charge black hole appearing in M-theory was found to be given by the ’hyperdeterminant’, a quantity introduced by the mathematician Cayley in 1845. Remarkably, the hyperdeterminant also measures the degree of tripartite entanglement shared by three qubits, the basic units of quantum information. It turned out that the different possible types of three-qubit entanglement corresponded directly to the different possible subclasses of this particular black hole. This initial observation provided a link relating various black holes and quantum information systems. Since then, we have been examining this two-way dictionary between black holes and qubits and have used our knowledge of M-theory to discover new things about multipartite entanglement and quantum information theory and, vice-versa, to garner new insights into black holes and M-theory. There is now a growing dictionary, which translates a variety of phenomena in one language to those in the other. Developing these fascinating relationships, exploiting them to better understand both M-theory and quantum entanglement is the goal of this thesis. In particular, we adopt the elegant mathematics of octonions, Jordan algebras and the Freudenthal triple system as our guiding framework. In the course of this investigation we will see how these fascinating algebraic structures can be used to quantify entanglement and define new black hole dualities.
47
Kang, Wei. "Correlation and cooperation in network information theory". College Park, Md. : University of Maryland, 2008. http://hdl.handle.net/1903/8355.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
48
Takahashi, Maki. "Studies in relativity and quantum information theory". Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/9915.
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This thesis explores a broad range of topics in the foundations of relativity and quantum information theory. The first and main topic of this thesis is on relativistic quantum information theory. Here we construct a reformulation of quantum information, which is consistent with relativity theory. We will see that by providing a rigorous formulation starting with the field equations for a massive fermion and a photon we can construct a theory for relativistic quantum information. In particular we provide a measurement formalism, a transport equation which describes the unitary evolution of a state through spacetime as well as how to extend this to multipartite systems. The second topic concerns the nature of time, duration and clocks in current physical theories and in particular for Newtonian mechanics. We analyse the relationship between the readings of clocks in Newtonian mechanics with absolute time. We will see that in order to answer this question we must provide not only a model for a clock but also solve what is referred to as Newton’s Scholium problem. We then compare this with other dynamical theories in particular quantum mechanics and general relativity where the treatment of time is quite different from Newtonian mechanics. The final topic is rather different from the first two. In this chapter we investigate a range of methods to perform tomography in a solid-state qubit device, for which a priori initialization and measurement of the qubit is restricted to a single basis of the Bloch sphere. We explore and compare several methods to acquire precise descriptions of additional states and measurements, quantifying both stochastic and systematic errors, ultimately leading to a tomographically-complete set that can be subsequently used in process tomography. We focus in detail on the example of a spin qubit formed by the singlet-triplet subspace of two electron spins in a GaAs double quantum dot, although our approach is quite general.
49
Simpson, Mark Aloysius. "Complexity Theory of Leadership and Management Information". ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/6121.
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Implementing effective leadership strategies in management of information systems (MIS) can positively influence overall organizational performance. This study was an exploration of the general problem of failure to lead effectively in the current knowledge-based economy and the resulting deleterious effects on organizational performance and threats to continuing organizational viability. The specific problem was the lack of understanding regarding the interaction of leadership processes with MIS functions and the impact on organizational success. Managers' and employees' lived experiences of leadership in small- to medium-sized enterprises were explored, as well as how those experiences influenced the organization's adaptive responses regarding technology and performance in the knowledge-based economy. The complexity theory of leadership was applied as the theoretical foundation for this study. A phenomenological methodology was used. Data were collected through semi-structured interviews and analyzed through open coding to identify emergent themes from the data. The themes were leaders motivate employees' positive work-related behaviors, effective communication skills ensure accessibility and efficiency of the organizational information system, and leadership practices influence business productivity. This study contributes to social change by providing insights for managers and employees regarding effective strategies for working as teams and networks via the use of nontraditional leadership theory, which promotes company sustainability by demonstrating the benefits of responding to the changing economy.
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Zonzo, Giuseppe. "Quantum Information Theory in Condensed Matter Physics". Doctoral thesis, Universita degli studi di Salerno, 2017. http://hdl.handle.net/10556/2625.
Texto completoResumen
2015 - 2016Inthe“standard”Gizburg-Landauapproach,aphasetransitionisintimately connected to a local order parameter, that spontaneously breaks some symmetries. In addition to the “traditional” symmetry-breaking ordered phases, a complex quantum system exhibits exotic phases, without classical counterpart, that can be described, for example, by introducing non-local order parameters that preserve symmetries. In this scenario, this thesis aims to shed light on open problems, such as the localdistinguishabilitybetweengroundstatesofasymmetry-breakingordered phase and the classification of one dimensional quantum orders, in terms of entanglement measures, in systems for which the Gizburg-Landau approach fails. In particular, I briefly introduce the basic tools that allow to understand the nature of entangled states and to quantify non-classical correlations. Therefore, I analyze the conjecture for which the maximally symmetry-breaking ground states (MSBGSs) are the most classical ones, and thus the only ones selected in real-world situations, among all the ground states of a symmetry-breaking ordered phase. I make the conjecture quantitatively precise, by proving that the MSBGSs are the only ones that: i) minimize pairwise quantum correlations, as measured by the quantum discord; ii) are always local convertible, by only applying LOCC transformations; iii) minimize the residual tangle, satisfying at its minimum the monogamy of entanglement. Moreover,Ianalyzehowevolvesthedistinguishability,afterasuddenchange of the Hamiltonian parameters. I introduce a quantitative measure of distinguishability, in terms of the trace distance between two reduced density matrices. Therefore, in the framework of two integrable models that falls in two different classes of symmetries, i.e. XY models in a transverse magnetic field and the N-cluster Ising models, I prove that the maximum of the distinguishability shows a time-exponential decay. Hence, in the limit of diverging time, all the informations about the particular initial ground state disappear, even if a system is integrable. Far away from the Gizburg-Landau scenario, I analyze a family of fullyanalyticalsolvableonedimensionalspin-1/2models,namedtheN-clustermodels in a transverse magnetic field. Regardless of the cluster size N + 2, these modelsexhibitaquantumphasetransition,thatseparatesaparamagneticphase from a cluster one. The cluster phase coresponds to a nematic ordered phase or a symmetry-protected topological ordered one, for even or odd N respectively. Using the Jordan-Wigner transformations, it is possible to diagonalize these models and derive all their spin correlation functions, with which reconstruct their entanglement properties. In particular, I prove that these models have only a non-vanishing bipartite entanglement, as measured by the concurrence, between spins at the endpoints of the cluster, for a magnetic field strong enough. Moreover, I introduce the minimal set of nonlinear ground-states functionals to detect all 1-D quantum orders for systems of spin-1/2 and fermions. I show that the von Neumann entanglement entropy distinguishes a critical systemfromanoncriticalone,becauseofthelogarithmicdivergenceataquantum critical point. The Schmidt gap detect the disorder of a system , because it saturates to a constant value in a paramagnetic phase and goes to zero otherwise. The mutual information, between two subsystems macroscopically separated, identifiesthesymmetry-breakingorderedphases,becauseofitsdependenceon the order parameters. The topological order phases, instead, via their deeply non-locality, can be characterized by analyzing all three functionals. [edited by author]
In aggiunta alle tradizionali fasi ordinate con rottura spontanea di simmetria, ben descritte con un approccio alla Gizburg-Landau, dove una transizione di fase `e intimamente connessa alla rottura spontanea di qualche simmetria e ad un parametro d’ordine locale, un sistema quantistico presenta anche fasi esotiche,senzaanalogoclassico,chesonoperesempiocaratterizzatedaparametri d’ordine non locali, senza una necessaria rottura di simmetria. Partendo da questi presupposti, questa tesi si pone come obiettivo quello di fare luce su alcuni problemi ancora aperti, come la distinguibilit`a tra stati fondamentaliinsistemiquantisticiconrotturaspontaneadisimmetriaelaclassificazionedituttelefasipresentiinsistemiunidimensionalidispin-1/2efermioni, per i quali l’approccio alla Gizburg-Landau non fornisce una descrizione adeguata. Inparticolare,sid`aunaspiegazioneall’ipotesisecondolaqualeglistatifondamentali che rompono massimamente la simmetria sono quelli pi`u classici, e quindi selezionati dalla decoerenza dell’ambiente, tra tutti gli stati fondamentali,edenergeticamenteequivalenti,diunafaseordinataconrotturaspontanea di simmetria. Si dimostra, infatti, che gli stati che rompono massimamente la simmetria sono gli unici stati che soddisfano tre criteri di classicalit`a: i) minimizzano l’entanglement bipartito, come quantificato dalla discord; ii) sono gli uniciversocuituttiglialtristatifondamentalisonolocalmenteconvertibili,mediante LOCC; iii) minimizzano il tangle residuo, soddisfacendo al minimo la monogamia dell’entanglement. Viene analizzato, inoltre, come evolve la distinguibilit`a tra stati fondamentali, dopo un quench dei parametri Hamiltoniani. Dopo aver introdotto una misura quantitativa della distinguibilit`a, in termini della distanza tra due matrici densit`a ridotte, si dimostra, per due sistemi integrabili con diverse classi di simmetria, nel dettaglio il modello XY in campo magnetico e i modelli NclusterIsing,cheladistinguibilit`adecadeesponenzialmenteneltempoequindi, nel limite di tempi lunghi, tutte le informazioni sullo stato fondamentale di partenza si perdono, anche per sistemi integrabili, nei quali la termalizzazione non si verifica. LontanodalloscenarioGizburg-Landau,sianalizzaunafamigliadimodelli di spin-1/2 esattamente risolvibili, nel dettaglio i modelli N-cluster in campo magnetico, che mostrano una transizione tra una fase disordinata e una di tipo cluster, che pu`o essere nematica o topologica, rispettivamente per N pari o dispari. Usando le trasformazioni di Jordan-Wigner `e possibile diagonalizzare questi modelli, ricavare lo stato fondamentale, le funzioni di correlazione fermioniche e tutte le loro propriet`a di entanglement di. Si dimostra che questi modellinonhannoentanglementmultipartito,masoloentanglementbipartito, come misurato dalla concurrence, tra due spin alle estremit`a del cluster, per un campo magnetico sufficientemente intenso. Inoltre, sidimostrachel’entropiadivonNeumann,loSchmidtgapelamutualinformationrappresentanoilsetminimodifunzionalinonlinearidellamatrice densit`a ridotta, mediante le quali caratterizzare tutte le fasi presenti in sistemi unidimensionali di spin -1/2 e fermioni. In particolare, l’entropia di von Neumann caratterizza la criticalit`a del sistema, per la sua divergenza logaritmica al punto critico; lo Schmidt gap caratterizza il disordine di un sistema, perch´e satura ad un valore costante nelle fasi disordinate e va rapidamente a zero altrove; la mutual information cattura le fasi ordinate con rottura spontanea di simmetria, per le quali cio` e `e possibile definire un parametro d’ordine diverso da zero su un supporto finito. Le fasi topologiche, per via della loro natura fortemente non locale, necessitano di tutte e tre i funzionali per essere individuate. [a cura dell'autore]
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