Dissertations / Theses on the topic 'Recurrent Problems'
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Meister, Daniel. "The complexity of membership problems for finite recurrent systems and minimal triangulations." Doctoral thesis, [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981745369.
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Singh, Jayant. "Optimization Problems Arising in Stability Analysis of Discrete Time Recurrent Neural Networks." Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25537.
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We consider the method of Reduction of Dissipativity Domain to prove global Lyapunov
stability of Discrete Time Recurrent Neural Networks. The standard and advanced criteria for
Absolute Stability of these essentially nonlinear systems produce rather weak results. The method
mentioned above is proved to be more powerful. It involves a multi-step procedure with maximization
of special nonconvex functions over polytopes on every step. We derive conditions which
guarantee an existence of at most one point of local maximum for such functions over every hyperplane.
This nontrivial result is valid for wide range of neuron transfer functions.
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Bell, Tannisha D. "An Examination of Race and Recurrent Substance Problems in the United States." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/9582.
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Several studies show that African-Americans are less likely than whites to use alcohol or drugs. However, if African-Americans use drugs then they are more likely to become heavy and persistent users. African-Americans are also more likely to have a current substance abuse disorder. There is not much in the literature to explain this phenomenon. The purpose of this study is to examine the alcohol and drug abuse, use and dependence of blacks and whites in order to explain the differences in the course of the substance disorder, using data from the National Comorbidity Survey. There are many variables thought to contribute to the racial difference, such as socio-economic status (measured by income and education), religion, insurance, employment status, and marital status. The data in this literature indicate that the aforementioned variables do not explain the racial difference in substance disorders. However, after performing interaction analyses, it is clear that the effects of treatment are different for blacks and whites. Treatment is more effective for whites, and it may even cause the substance disorder to become worse for blacks. Several studies indicate that this may be the result of cultural differences between the treatment staff and the clients.Master of Science
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Nakayama, Masataka. "The problems of serial order in language:Clustering, context discrimination, temporal distance, and edges." Kyoto University, 2015. http://hdl.handle.net/2433/200480.
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Jeffrey, James Howard. "Recurrent problems in the construction process : an action research study of the design and construction quality of hospital en-suites." Thesis, University of Salford, 2010. http://usir.salford.ac.uk/26736/.
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Research was undertaken based upon the suspicion that there were recurrent problems with the design and construction of hospital en-suites. An investigation was planned to confirm whether or not this suspicion was true and that there were, in fact, recurrent problems. Following on from this it would be to find out if they existed, what they were and whether and how they could be overcome. These objectives needed to be formulated, and then positioned within a framework that identified if the practitioners within the industry even knew about the problems and if they did, whether they chose not to resolve them or could not overcome the barriers that prevented the resolution. A review of the Literature identified that little research had been undertaken in the area of problems with the design and construction of hospital en-suites. The broader perspective of problems within the construction industry was covered by the theories supporting construction Process Improvement. This area was reviewed and it was found that the results of practical implementation of Process Improvement were rather less successful than had originally been anticipated. The Sub-processes that combined together to make up the whole processes were considered and reviewed also. Theories relating to the improvement of the Sub-process of Design; Management, Quality and Briefing were reviewed. These reviews of the Process and Design Sub-processes identified that there were significant barriers within organisation that made improvements difficult to implement. The opportunity arose to review the suggested existence of problems with the design and construction of hospital en-suites by way of case Study research at the £330million Derby PFI hospital redevelopment. At this project approximately 400 en-suites were going to be constructed. Action Research was proposed to implement practical interventions aimed at identifying the problems and their solutions. During the course of the research a second project, the similarly sized £330 million PFI redevelopment of the Mansfield hospital project, also with approximately 400 en-suites. This provided the basis for a second Case Study. The original research approach of Action Research within a Case Study was modified to two Case Studies each embracing Action Research contained within an overarching Action Research strategy. Planned interventions in the construction processes were undertaken to identify whether knowledge could become embedded in that construction process that would eliminate any problems identified in the design and construction of hospital en-suites. The techniques for information gathering included workshops, constructing Mock-ups, Simulation exercises, Structured interview based on carefully prepared Questionnaires to form agenda's and Site Visits. From the research emerged the 'Notion of Solute' as a theoretical model for problem resolution which overcomes the difficulty of Knowledge Transfer. From the investigations within the two Case Studies into hospital en-suites a solution to the problems required the transfer of the knowledge of three components: The nature of the problems, The implications of not remedying the problems. Recommendations for resolving the problems. These three components, which formulate the solutions, were suggested to be defined as a 'Solute'. This is a distinct and focussed 'package of knowledge' that can be readily transferred, both between individuals and also between projects. This 'Solute' is a theoreticz model that could be transferred to other problems within hospitals, other problems within construction projects and even to problems in other industries. Each 'Solute' is then populated with the specific parameters required to enable a problem to be understood and a solution to be implemented. Keywords: Knowledge, Design, Quality, Hospital, En-suite.
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CAROTA, MASSIMO. "Neural network approach to problems of static/dynamic classification." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/580.
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The purpose of my doctorate work has consisted in the exploration of the potentialities and of the
effectiveness of different neural classifiers, by experimenting their application in the solution of
classification problems occurring in the fields of interest typical of the research group of the
“Laboratorio Circuiti” at the Department of Electronic Engineering in Tor Vergata.
Moreover, though inspired by works already developed by other scholars, the adopted neural
classifiers have been partially modified, in order to add to them interesting peculiarities not present
in the original versions, as well as to adapt them to the applications of interest.
These applications can be grouped in two great families. As regards the first application, the objects
to be classified are identified by features of static nature, while as regards the second family, the
objects to be classified are identified by features evolving in time. In relation to the research fields
taken as reference, the ones that belong to the first family are the following:
• classification, by means of fuzzy algorithms, of acoustic signals, with the aim of attributing
them to the source that generated them (recognition of musical instruments)
• exclusive classification of simple human motor acts for the purpose of a precocious
diagnosis of nervous system diseases
The second family of application has been represented by that research field that aims to the
development of neural tools for the Automatic Tanscription of piano pieces.
The first part of this thesis has been devoted to the detailed description of the adopted neural
classification techniques, as well as of the modifications introduced in order to improve their
behavior in relation to the particular applications. In the second part, the experiments by means of
which I have estimated the before-mentioned neural classification techniques have been introduced.
It exactly deals with experiments carried out in the chosen research fields. For every application, the
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results achieved have been reported; in some cases, the further steps to perform have also been
proposed.
After a brief introduction to the biological neural model, a description follows about the model of
the artificial neuron that has afterwards inspired all the other models: the one proposed by
McCulloch and Pitts in 1943. Subsequently, the different typologies of architectures that
characterize neural networks are shortly introduced, as regards the feed-forward networks as well as
the recursive networks. Then, a description of some learning strategies (supervised and
unsupervised), adopted in order to train neural networks, is also given; some criteria by means of
which one can estimate the goodness of an opportunely trained neural network are also given
(errors made vs. generalization capability). A great part of the adopted networks is based on
adaptations of the Backpropagation algorithm; the other networks have been instead trained by
means of algorithms based on statistical or geometric criteria. The Backpropagation algorithm has
been improved by augmenting the degrees of freedom to the learning ability of a feed-forward
neural network with the introduction of a spline adaptive activation function. A wide description
has been given of the recurrent neural networks and particularly of the locally recurrent neural
networks, networks for dynamic classification exploited in the automatic transcription of piano
music.
After a more or less rigorous definition of the concepts of classification and clustering, some
paragraphs have been devoted to some statistical and geometric neural architectures, exploited in
the implementation of static classifiers of common use and in particular in the application fields that
have regarded my doctorate work.
A separate paragraph has been devoted to the Simpson’s classifier and to the variants originated
from my research work. They have revealed themselves to be static classifiers very simple to
implement and at the same time very ductile and efficient, in many situations as well as regards the
problem of musical source recognition. Two have been the choices in this case. In the first one,
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these classifiers have been trained, by means of a pure supervised learning approach, while in the
second the training algorithm, though keeping a substantially supervised nature, is prepared by a
clustering phase, with the aim of improving, in terms of errors and generalization, the covering of
the input space. Subsequently, the locally recurrent neural networks seen as dynamic classifiers are
retrieved. However, their training has been rethought according to the effective reduction of the
classification error instead of the classic mean-square error.
The last three paragraphs have been devoted to a detailed description, in terms of specifications,
implementative choices and final results, of the aforesaid fields of applications. The results obtained
in all the three fields of application can be considered encouraging. Particularly, the recognition of
musical instruments by means of the adopted neural networks has shown results tha can be
considered out comparable if not better than those obtained by means of other techniques, but with
considerably less complex structures. In case of the Automatic Transcription of piano pieces, the
dynamic networks I adopted have given good results. Unfortunately, the required computational
resources required by such networks cannot be considered negligible. As far as the medical
applications, we are still in an incipent phase of the research. However, opinions expressed by those
people who work in this field can be considered substantially eulogistic.
The research activities my doctorate work is part of have been carried out in collaboration with the
Department “INFOCOM” of the first University of Rome “La Sapienza”, as far as the recognition
of musical instruments and the Automatic Transcription of piano pieces. The necessity to study the
potentialities of neural classifiers in medical application has instead come from a profitable existing
collaboration with the Istituto Superiore di Sanità in Rome.
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Mossina, Luca. "Applications d'apprentissage automatique à la résolution de problèmes récurrents en optimisation combinatoire." Electronic Thesis or Diss., Toulouse, ISAE, 2020. http://www.theses.fr/2020ESAE0043.
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Ce travail s'intéresse aux problèmes de décision pour lesquels on cherche une solution optimale ou quasi-optimale et dont il faut résoudre plusieurs instances successives (problèmes récurrents) lesquelles sont des variantes d'un même problème d'origine.On analyse la structure de tels problèmes afin de dégager les caractéristiques pouvant être exploitées efficacement et transférées d'une résolution à l'autre, afin d'améliorer incrémentalement la qualité de l'optimisation.On se place donc dans le cadre d'une interaction entre un processus d'apprentissage automatique (fouille de données d'optimisation) et un processus d'optimisation.D'une part, étant donné l'expérience de résolutions passées, on cherche à apprendre ce que l'on peut généraliser au problème courant.D'autre part, on cherche à utiliser ces connaissances au sein de l'algorithme d'optimisation afin de rendre son exécution plus efficace.En particulier, cette thèse présente trois contributions. La première introduit une méthode pour générer des sous-problèmes plus simple pour un instance d’un problème récurrent, en utilisant la classification multi-étiquette. Un sous-ensemble de variables décision est sélectionné et figé à une valeur de référence.La solution au sous-problème qui reste, même en étant pas garantie optimale pour le problème originale, peut être obtenu plus rapidement.La deuxième, emploie l’apprentissage supervisé, classification et régression, pour prédire et ajouter une contrainte additionnelle au problème récurrent modélisé par programmation mathématique. Au moment de résoudre une nouvelle instance, le modèle prédit en quelle mesure la solution au problème de référence est applicable, en permettant d’obtenir une résolution plus rapide.Dans la troisième, le contrôle dynamique de paramètres d’un algorithme évolutionnaire est encadré comme un problème d’apprentissage par renforcement. Les politiques de contrôle ainsi obtenues garantissent que l’algorithme d’optimisation atteint, en moyenne, la solution optimale dans le plus court délaiThe interest is on those decision problems for which an optimal or quasi-optimal solution is sought, and for which it is necessary to solve successive instances (recurrent problems) that are variations of a common original problem.The structure of such problems is analysed to identify the characteristics that can be exploited and transferred from one resolution to another, to incrementally improve the quality of the optimization process. The research is characterized by the interaction between a process of statistical learning (from optimization data) and a process of optimization. The information extracted from past resolutions is generalized to the current problem and integrated into the optimization algorithm to make its execution more resource-efficient.In particular, this thesis presents three contributions.The first, introduces a method that generates a simpler sub-problem to an instance of a recurrent problem, using multi-label classification. A subset of decision variables is selected and set to a reference value. The solution to the remaining sub-problem, while not guaranteed to be optimal for the original problem, can be obtained faster.The second employs Supervised Learning, classification and regression, to predict an additional constraint to a reference recurrent problem modelled via Mathematical Programming. When a new instance is solved, the model predicts how much of the solution to the reference problem is still applicable, allowing for a more rapid resolution.In the third, the dynamic control of the parameters of Evolutionary Algorithms is framed as a Reinforcement Learning problem. The control policies obtained guarantee that the optimization algorithm reaches an optimal solution within the shortest, average time
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Bermell, Måns. "Identification of Problem Gambling via Recurrent Neural Networks : Predicting self-exclusion due to problem gambling within the remote gambling sector by means of recurrent neural networks." Thesis, Umeå universitet, Institutionen för fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-159125.
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Under recent years the gambling industry has been moving towards providing their customer the possibility to gamble online instead of visiting a physical location. Aggressive marketing, fast growth and a multitude of actors within the market have resulted in a spike of customers who have developed a gambling problem. Decision makers are trying to fight back by regulating markets in order to make the companies take responsibility and work towards preventing these problems. One method of working proactively in this regards is to identify vulnerable customers before they develop a destructive habit. In this work a novel method of predicting customers that have a higher risk in regards to gambling-related problems is explored. More concretely, a recurrent neural network with long short-term memory cells is created to process raw behaviour data that are aggregated on a daily basis to classify them as high-risk or not. Supervised training is used in order to learn from historical data, where the usage of permanent self-exclusions due to gambling related problems defines problem gamblers. The work consists of: obtain a local optimal configuration of the network which enhances the performance for identifying problem gam- blers who favour the casino section over sports section, and analyze the model to provide insights in the field. This project was carried out together with LeoVegas Mobile Gaming Group. The group offers both online casino games and sports booking in a number of countries in Europe. This collaboration made both data and expertise within the industry accessible to perform this work. The company currently have a model in production to perform these predictions, but want to explore other approaches. The model that has been developed showed a significant increase in performance compared to the one that is currently used at the company. Specifically, the precision and recall which are two metrics important for a two class classification model, increased by 37% and 21% respectively. Using raw time series data, instead of aggregated data increased the responsiveness regarding customers change in behaviour over time. The model also scaled better with more history compared to the current model, which could be a result of the nature of a recurrent network compared to the current model used.
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Nielinger-Vakil, Carola. "Aphorism as a recurring problem in musical construction." Thesis, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300927.
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Benini, Fabriciu Alarcão Veiga. "Rede neural recorrente com perturbação simultânea aplicada no problema do caixeiro viajante." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18153/tde-29042009-102601/.
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O presente trabalho propõe resolver o clássico problema combinatorial conhecido como problema do caixeiro viajante. Foi usado no sistema de otimização de busca do menor caminho uma rede neural recorrente. A topologia de estrutura de ligação das realimentações da rede adotada aqui é conhecida por rede recorrente de Wang. Como regra de treinamento de seus pesos sinápticos foi adotada a técnica de perturbação simultânea com aproximação estocástica. Foi elaborado ainda uma minuciosa revisão bibliográfica sobre todos os temas abordados com detalhes sobre a otimização multivariável com perturbação simultânea. Comparar-se-á também os resultados obtidos aqui com outras diferentes técnicas aplicadas no problema do caixeiro viajante visando propósitos de validação.This work proposes to solve the classic combinatorial optimization problem known as traveling salesman problem. A recurrent neural network was used in the system of optimization to search the shorter path. The structural topology linking the feedbacks of the network adopted here is known by Wang recurrent network. As learning rule to find the appropriate values of the weights was used the simultaneous perturbation with stochastic approximation. A detailed bibliographical revision on multivariable optimization with simultaneous perturbation is also described. Comparative results with other different techniques applied to the traveling salesman are still presented for validation purposes.
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Venturella, Michael Anthony. "Modal Analysis of the Ice-Structure Interaction Problem." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/31749.
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In the present study, the author builds upon the single degree of freedom ice-structure interaction model initially proposed by Matlock, et al. (1969, 1971). The model created by Matlock, et al. (1969, 1971), assumed that the primary response of the structure would be in its fundamental mode of vibration. In order to glean a greater physical understanding of ice-structure interaction phenomena, it was critical that this study set out to develop a multi-mode forced response for the pier when a moving ice floe makes contact at a specific vertical pier location. Modal analysis is used in which the response of each mode is superposed to find the full modal response of the entire length of a pier subject to incremental ice loading. This incremental ice loading includes ice fracture points as well as loss of contact between ice and structure. In this model, the physical system is a bottom supported pier modeled as a cantilever beam. The frequencies at which vibration naturally occurs, and the mode shapes which the vibrating pier assumes, are properties which can be determined analytically and thus a more precise picture of pier vibration under ice loading is presented. Realistic conditions such as ice accumulation on the pier modeled as a point mass and uncertainties in the ice characteristics are introduced in order to provide a stochastic response. The impact of number of modes in modeling is studied as well as dynamics due to fluctuations of ice impact height as a result of typical tidal fluctuations. A Poincaré based analysis following on the research of Karr, et al. (1992) is employed to identify any periodic behavior of the system response. Recurrence plotting is also utilized to further define any existing structure of the ice-structure interaction time series for low and high speed floes. The intention of this work is to provide a foundation for future research coupling multiple piers and connecting structure for a comprehensive ice-wind-structural dynamics model.Master of Science
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Pinheiro, Tárcius Alievi. "SOLUÇÕES NÃO CLÁSSICAS PARA PROBLEMAS DA OBMEP." Universidade Federal de Santa Maria, 2013. http://repositorio.ufsm.br/handle/1/10936.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorSince 2005 the Brazilian Mathematical Olympiad of Public Schools (OBMEP) is present in many schools involving students and teachers by presenting different problems when compared to traditional models of exercises presented in textbooks. There is some special challenge in questions of OBMEP, requiring creativity in its solutions. Collecting cards and answers of the last OBMEP, in five schools in the municipality of Passo Fundo, held on June 5, 2012, we realized that exercises that involve some kind of recursive solution, there were a large numbers of errors. The objective of this work is to present alternative solutions to some problems of the OBMEP, herewith encourage high school teachers to use recurrence as a tool in building models and general solutions to mathematical problems. For this, we present some basic notes about recursive sequences, as well as a study on mathematical recurrence of first and second order, proving some basic theorems and citing some examples for better understanding of the subject. We finish, solving questions that involve recursive reasoning and that are related to OBMEP highlighting the variety of content of basic education that can be used in solving such problems.
Desde 2005, a Olimpíada Brasileira de Matemática das Escolas Públicas (OBMEP) está presente em muitas escolas envolvendo alunos e professores. Isso ocorre porque a competição apresenta problemas diferenciados quando comparados aos modelos tradicionais de exercícios contidos em livros didáticos. As questões propostas na OBMEP possuem um caráter desafiador que requer criatividade na construção das soluções. Coletamos os cartõesrespostas da última OBMEP, realizada no dia cinco de junho de 2012, em cinco escolas do município de Passo Fundo, e percebemos que exercícios envolvendo algum tipo de raciocínio recursivo apresentaram um grande número de respostas erradas. O objetivo deste trabalho é apresentar soluções alternativas para alguns problemas da OBMEP visando encorajar o professor do ensino médio a abordar e utilizar recorrência como uma ferramenta na construção de modelos e soluções gerais para problemas matemáticos. Para isso apresentamos apontamentos realizados por alguns autores a respeito de sequências recursivas. Além disso, explanamos um estudo sobre recorrência matemática de primeira e segunda ordens, no qual expomos alguns teoremas e suas respectivas demonstrações e citamos exemplos básicos para melhor compreensão do assunto. Nessa linha, selecionamos e resolvemos quatro questões que envolvem raciocínio recursivo e que estão relacionadas à OBMEP salientando a variedade de conteúdos do ensino básico que podem ser utilizados na resolução de tais problemas.
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Kohler, Matthew. "What Can the Collective Action Problem Tell Us about the Recurrence of Civil War and the Long-term Stability of a Country?" Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4955/.
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This study attempts to explain why some countries experience multiple civil wars while others who have experienced a civil war build long-term stability from the rubble of conflict. The explanation of why civil war recurs focuses on the collective action problem, centering on the rebel leaders' ability to solve the Rebel's Dilemma. I further argue that once the Rebel's Dilemma has been solved once it is much easier for rebel leaders to solve it again and again. The empirical finds suggest that the political situation resulting from the first war plays a strong role in the solutions to the collective action problem and thus the long-term stability following a civil war. Namely, the level of democracy, partition and third party enforcement of the peace all affect the ability of the rebel leaders to solve the collective action problem and the likelihood of another civil war.
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Van, Lierde Boris. "Developing Box-Pushing Behaviours Using Evolutionary Robotics." Thesis, Högskolan Dalarna, Datateknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:du-6250.
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The context of this report and the IRIDIA laboratory are described in the preface. Evolutionary Robotics and the box-pushing task are presented in the introduction.The building of a test system supporting Evolutionary Robotics experiments is then detailed. This system is made of a robot simulator and a Genetic Algorithm. It is used to explore the possibility of evolving box-pushing behaviours. The bootstrapping problem is explained, and a novel approach for dealing with it is proposed, with results presented.Finally, ideas for extending this approach are presented in the conclusion.
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Ward, William. "The recurring problem of subtraction : implications and alternative solutions for teachers helping UK primary school children overcome mathematical difficulties." Thesis, University of Surrey, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395571.
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Souza, Márcia Erondina Dias de. "UMA PROPOSTA DE ABORDAGEM AO PROBLEMA DE FLÁVIO JOSEFO APLICADA AO ENSINO MÉDIO." Universidade Federal de Santa Maria, 2013. http://repositorio.ufsm.br/handle/1/10935.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorIn this paper, we presents a didactic sequence of activities designed for a group of students of high school, their age were about 15 and 18 years old, with the main objective to study the problem proposed by the mathematician Flávio Josefo, in mid-year 64. The legend tells that a group of rebels, including Flávio Josefo, was trapped in a cave by the enemy army. Preferring the suicide to capture, the rebels decided to form a circle and, counting over this, to kill each third person of the rest of the group. Josefo was contrary of this suicide pact therefore, together with a friend, calculated very quickly the appropriated positions that both should take in this circle in order to get out of this terrible situation. To understand this solution, we propose, at the first moment, a review about the numerical sequences, including the special cases of arithmetic and geometric. Then, we introduce some notions about the de recurrence relations and the Principle of Mathematical Induction, allowing a generalization of concepts and results already known intuitively by the student group.
Neste trabalho, apresentamos uma sequência didática de atividades elaboradas para um grupo de alunos do ensino médio, na faixa etária de 15 a 18 anos, tendo como principal objetivo estudar o problema proposto pelo matemático Flávio Josefo, nos meados do ano 64. Conta a lenda que um grupo de rebeldes, dentre eles Flávio Josefo, foi encurralado numa caverna pelo exército inimigo. Preferindo o suicídio à captura, os rebeldes decidiram formar um círculo e, contando ao longo deste, matar cada terceira pessoa restante do grupo. Josefo era contrário a este pacto suicida e, por isso, juntamente com um amigo, calculou muito rapidamente as posições adequadas que ambos deveriam tomar nesse círculo de modo a saírem ilesos desta terrível situação. Para o entendimento desta solução propomos, inicialmente, uma revisão sobre sequências numéricas, incluindo os casos especiais de progressão aritmética e geométrica. Em seguida, introduzimos algumas noções a respeito de relações de recorrência e do Princípio da Indução Matemática, permitindo uma generalização dos conceitos e resultados já conhecidos intuitivamente pelo grupo de alunos.
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Flesch, Alexis. "Bandes de confiance par vraisemblance empirique : δ-méthode fonctionnelle et applications aux processus des événements récurrents." Phd thesis, Université de Franche-Comté, 2012. http://tel.archives-ouvertes.fr/tel-00955359.
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Disposant d'un jeu de données sur des infections nosocomiales, nous utilisons des techniques de vraisemblance empirique pour construire des bandes de confiance pour certaines quantité d'intérêt. Cette étude nous amène à renforcer les outils déjà existants afin qu'ils s'adaptent à notre cadre. Nous présentons dans une première partie les outils mathématiques issus de la littérature que nous utilisons dans ce travail de thèse. Nous les appliquons ensuite à diverses situations et donnons de nouvelles démonstrations lorsque cela est nécessaire. Nous conduisons aussi des simulations et obtenons des résultats concrets concernant notre jeu de données. Enfin, nous détaillons les algorithmes utilisés.
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Silva, Andrea Piranhe da. "Um estudo dos zeros de polinômios ortogonais na reta real e no círculo unitário e outros polinômios relacionados." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-18122017-110406/.
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O principal objetivo deste trabalho 6 estudar o comportamento dos zeros de polinômios ortogonais e similares. Inicialmente, consideramos uma relação entre duas sequências ele polinômios ortogonais, onde as medidas associadas estão relacionadas entre si. Usamos esta relação para estudar as propriedades de monotonicidade dos zeros dos polinômios ortogonais relacionados a uma medida obtida através da generalização da medida associada a uma outra sequência de polinômios ortogonais. Apresentamos, como exemplos, os polinômios ortogonais obtidos a partir da generalização das medidas associadas aos polinômios de Jacobi, Laguerre e Charlier. Em urna segunda etapa, consideramos polinômios gerados por uma certa relação de recorrência de três termos com o objetivo de encontrar limitantes, em termos dos coeficientes da relação de recorrência, para as regiões onde os zeros estão localizados. Os zeros são estudados através do problema de autovalor associado a uma matriz de Hessenberg. Aplicações aos polinômios de Szegó, polinômios para-ortogonais e polinômios com coeficientes complexos não-nulos são consideradas.The main purpose of this work is to study the behavior of the zeros of orthogonal and similar polynomials. Initially, we consider a relation between two sequences of orthogonal polynomials, where the associated measures are related to each other. We use this relation to study the monotonicity propertios of the zeros of orthogonal polynomials related with a measure obtained through a generalization of the measure associated with other sequence of orthogonal polynomials. As examples, we consider the orthogonal polynomials obtained in this way from the measures associated with the Jacobi, Laguerre and Charlier polynomials. We also consider the zeros of polynomials generated by a certain three term recurrence relation. Here, the main objective is to find bounds, in terms of the coefficients of the recurrence relation, for the regions where the zeros are located. The zeros are explored through an eigenvalue representation associated with a Hessenberg matrix. Applications to Szegõ polynomials, para-orthogonal polynomials anti polynomials with non-zero complex coefficients are considered.
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Kaumanns, Franz David [Verfasser], and Hinrich [Akademischer Betreuer] Schütze. "Assessment and analysis of the applicability of recurrent neural networks to natural language understanding with a focus on the problem of coreference resolution / Franz David Kaumanns ; Betreuer: Hinrich Schütze." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/1121507999/34.
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Nunes, Josiani Batista [UNESP]. "Limitantes para os zeros de polinômios gerados por uma relação de recorrência de três termos." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/94251.
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nunes_jb_me_sjrp.pdf: 1005590 bytes, checksum: 7da54a97a1f2ab452a315062071f2c4e (MD5)Este trabalho trata do estudo da localização dos zeros dos polinômios gerados por uma determinada relação de recorrência de três termos. O objetivo principal é estudar limitantes, em termos dos coeficientes da relação de recorrência, para as regiões onde os zeros estão localizados. Os zeros são explorados atravé do problema de autovalor associado a uma matriz de Hessenberg. As aplicações são consideradas para polinômios de Szego fSng, alguns polinômios para- ortogonais ½Sn(z) + S¤n (z) 1 + Sn(0) ¾ e ½Sn(z) ¡ S¤n (z) 1 ¡ Sn+1(0) ¾, especialmente quando os coeficientes de reflexão são reais. Um outro caso especial considerado são os zeros do polinômio Pn(z) = n Xm=0 bmzm, onde os coeficientes bm; para m = 0; 1; : : : ; n, são complexos e diferentes de zeros.
In this work we studied the localization the zeros of polynomials generated by a certain three term recurrence relation. The main objective is to study bounds, in terms of the coe±cients of the recurrence relation, for the regions where the zeros are located. The zeros are explored through an eigenvalue representation associated with a Hessenberg matrix. Applications are considered to Szeg}o polynomials fSng, some para-orthogonal polyno- mials ½Sn(z) + S¤n (z) 1 + Sn(0) ¾and ½Sn(z) ¡ S¤n (z) 1 ¡ Sn+1(0) ¾, especially when the re°ection coe±cients are real. As another special case, the zeros of the polynomial Pn(z) = n Xm=0 bmzm, where the non-zero complex coe±cients bm for m = 0; 1; : : : ; n, were considered.
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Vandomme, Elise. "Contributions to combinatorics on words in an abelian context and covering problems in graphs." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GRENM010/document.
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Cette dissertation se divise en deux parties, distinctes mais connexes, qui sont le reflet de la cotutelle. Nous étudions et résolvons des problèmes concernant d'une part la combinatoire des mots dans un contexte abélien et d'autre part des problèmes de couverture dans des graphes. Chaque question fait l'objet d'un chapitre. En combinatoire des mots, le premier problème considéré s'intéresse à la régularité des suites au sens défini par Allouche et Shallit. Nous montrons qu'une suite qui satisfait une certaine propriété de symétrie est 2-régulière. Ensuite, nous appliquons ce théorème pour montrer que les fonctions de complexité 2-abélienne du mot de Thue--Morse ainsi que du mot appelé ''period-doubling'' sont 2-régulières. Les calculs et arguments développés dans ces démonstrations s'inscrivent dans un schéma plus général que nous espérons pouvoir utiliser à nouveau pour prouver d'autres résultats de régularité. Le deuxième problème poursuit le développement de la notion de mot de retour abélien introduite par Puzynina et Zamboni. Nous obtenons une caractérisation des mots sturmiens avec un intercepte non nul en termes du cardinal (fini ou non) de l'ensemble des mots de retour abélien par rapport à tous les préfixes. Nous décrivons cet ensemble pour Fibonacci ainsi que pour Thue--Morse (bien que cela ne soit pas un mot sturmien). Nous étudions la relation existante entre la complexité abélienne et le cardinal de cet ensemble. En théorie des graphes, le premier problème considéré traite des codes identifiants dans les graphes. Ces codes ont été introduits par Karpovsky, Chakrabarty et Levitin pour modéliser un problème de détection de défaillance dans des réseaux multiprocesseurs. Le rapport entre la taille optimale d'un code identifiant et la taille optimale du relâchement fractionnaire d'un code identifiant est comprise entre 1 et 2 ln(|V|)+1 où V est l'ensemble des sommets du graphe. Nous nous concentrons sur les graphes sommet-transitifs, car nous pouvons y calculer précisément la solution fractionnaire. Nous exhibons des familles infinies, appelées quadrangles généralisés, de graphes sommet-transitifs pour lesquelles les solutions entière et fractionnaire sont de l'ordre |V|^k avec k dans {1/4, 1/3, 2/5}. Le second problème concerne les (r,a,b)-codes couvrants de la grille infinie déjà étudiés par Axenovich et Puzynina. Nous introduisons la notion de 2-coloriages constants de graphes pondérés et nous les étudions dans le cas de quatre cycles pondérés particuliers. Nous présentons une méthode permettant de lier ces 2-coloriages aux codes couvrants. Enfin, nous déterminons les valeurs exactes des constantes a et b de tout (r,a,b)-code couvrant de la grille infinie avec |a-b|>4. Il s'agit d'une extension d'un théorème d'AxenovichThis dissertation is divided into two (distinct but connected) parts that reflect the joint PhD. We study and we solve several questions regarding on the one hand combinatorics on words in an abelian context and on the other hand covering problems in graphs. Each particular problem is the topic of a chapter. In combinatorics on words, the first problem considered focuses on the 2-regularity of sequences in the sense of Allouche and Shallit. We prove that a sequence satisfying a certain symmetry property is 2-regular. Then we apply this theorem to show that the 2-abelian complexity functions of the Thue--Morse word and the period-doubling word are 2-regular. The computation and arguments leading to these results fit into a quite general scheme that we hope can be used again to prove additional regularity results. The second question concerns the notion of return words up to abelian equivalence, introduced by Puzynina and Zamboni. We obtain a characterization of Sturmian words with non-zero intercept in terms of the finiteness of the set of abelian return words to all prefixes. We describe this set of abelian returns for the Fibonacci word but also for the Thue-Morse word (which is not Sturmian). We investigate the relationship existing between the abelian complexity and the finiteness of this set. In graph theory, the first problem considered deals with identifying codes in graphs. These codes were introduced by Karpovsky, Chakrabarty and Levitin to model fault-diagnosis in multiprocessor systems. The ratio between the optimal size of an identifying code and the optimal size of a fractional relaxation of an identifying code is between 1 and 2 ln(|V|)+1 where V is the vertex set of the graph. We focus on vertex-transitive graphs, since we can compute the exact fractional solution for them. We exhibit infinite families, called generalized quadrangles, of vertex-transitive graphs with integer and fractional identifying codes of order |V|^k with k in {1/4,1/3,2/5}. The second problem concerns (r,a,b)-covering codes of the infinite grid already studied by Axenovich and Puzynina. We introduce the notion of constant 2-labellings of weighted graphs and study them in four particular weighted cycles. We present a method to link these labellings with covering codes. Finally, we determine the precise values of the constants a and b of any (r,a,b)-covering code of the infinite grid with |a-b|>4. This is an extension of a theorem of Axenovich
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Lani, James Anthony. "Improving a Marker-Based System to Rate Assimilation of Problematic Experiences." Miami University / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=miami1055936557.
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Jones, Benjamin Thomas. "The Past is Ever-Present: Civil War as a Dynamic Process." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1374173688.
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Nunes, Josiani Batista. "Limitantes para os zeros de polinômios gerados por uma relação de recorrência de três termos /." São José do Rio Preto : [s.n.], 2009. http://hdl.handle.net/11449/94251.
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Orientador: Eliana Xavier Linhares de AndradeBanca: Alagacone Sri Ranga
Banca: Andre Piranhe da Silva
Resumo: Este trabalho trata do estudo da localização dos zeros dos polinômios gerados por uma determinada relação de recorrência de três termos. O objetivo principal é estudar limitantes, em termos dos coeficientes da relação de recorrência, para as regiões onde os zeros estão localizados. Os zeros são explorados atravé do problema de autovalor associado a uma matriz de Hessenberg. As aplicações são consideradas para polinômios de Szeg"o fSng, alguns polinômios para- ortogonais ½Sn(z) + S¤n (z) 1 + Sn(0) ¾ e ½Sn(z) ¡ S¤n (z) 1 ¡ Sn+1(0) ¾, especialmente quando os coeficientes de reflexão são reais. Um outro caso especial considerado são os zeros do polinômio Pn(z) = n Xm=0 bmzm, onde os coeficientes bm; para m = 0; 1; : : : ; n, são complexos e diferentes de zeros.
Abstract: In this work we studied the localization the zeros of polynomials generated by a certain three term recurrence relation. The main objective is to study bounds, in terms of the coe±cients of the recurrence relation, for the regions where the zeros are located. The zeros are explored through an eigenvalue representation associated with a Hessenberg matrix. Applications are considered to Szeg}o polynomials fSng, some para-orthogonal polyno- mials ½Sn(z) + S¤n (z) 1 + Sn(0) ¾and ½Sn(z) ¡ S¤n (z) 1 ¡ Sn+1(0) ¾, especially when the re°ection coe±cients are real. As another special case, the zeros of the polynomial Pn(z) = n Xm=0 bmzm, where the non-zero complex coe±cients bm for m = 0; 1; : : : ; n, were considered.
Mestre
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"Solving variational inequalities and related problems using recurrent neural networks." Thesis, 2007. http://library.cuhk.edu.hk/record=b6074418.
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During the past two decades, numerous recurrent neural networks (RNNs) have been proposed for solving VIs and related problems. However, first, the theories of many emerging RNNs have not been well founded yet; and their capabilities have been underestimated. Second, these RNNs have limitations in handling some types of problems. Third, it is certainly not true that these RNNs are best choices for solving all problems, and new network models with more favorable characteristics could be devised for solving specific problems.In the research, the above issues are extensively explored from dynamic system perspective, which leads to the following major contributions. On one hand, many new capabilities of some existing RNNs have been revealed for solving VIs and related problems. On the other hand, several new RNNs have been invented for solving some types of these problems. The contributions are established on the following facts. First, two existing RNNs, called TLPNN and PNN, are found to be capable of solving pseudomonotone VIs and related problems with simple bound constraints. Second, many more stability results are revealed for an existing RNN, called GPNN, for solving GVIs with simple bound constraints, and it is then extended to solve linear VIs (LVIs) and generalized linear VIs (GLVIs) with polyhedron constraints. Third, a new RNN, called IDNN, is proposed for solving a special class of quadratic programming problems which features lower structural complexity compared with existing RNNs. Fourth, some local convergence results of an existing RNN, called EPNN, for nonconvex optimization are obtained, and two variants of the network by incorporating two augmented Lagrangian function techniques are proposed for seeking Karush-Kuhn-Tucker (KKT) points, especially local optima, of the problems.
Variational inequality (VI) can be viewed as a natural framework for unifying the treatment of equilibrium problems, and hence has applications across many disciplines. In addition, many typical problems are closely related to VI, including general VI (GVI), complementarity problem (CP), generalized CP (GCP) and optimization problem (OP).
Hu, Xiaolin.
"July 2007."
Adviser: Jun Wang.
Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1102.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2007.
Includes bibliographical references (p. 193-207).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract in English and Chinese.
School code: 1307.
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Wei, Zhu Zhen, and 朱振緯. "Discriminability-Optimization-Based Recurrent Fuzzy Neural Networks for Classification Problems." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/20974608071614806883.
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博士國立暨南國際大學
電機工程學系
101
The discriminative capability plays a significant role in determining classification performance. To increase the discriminative capability, this thesis proposes a Takagi–Sugeno(TS)-type maximizing-discriminability-based recurrent fuzzy network (MDRFN) which can classify highly confusable patterns. The proposed MDRFN considers minimum classification error (MCE) and minimum training error (MTE). In MCE, the weights are updated by maximizing the discrimination among different classes. In MTE, the parameter learning adopts the gradient–descent method to reduce the cost function. Therefore, the novelty of MDRFN is that it not only minimizes the cost function but maximizes the discriminative capability as well. Moreover, to enhance the “discriminability”, an enhanced discriminability recurrent fuzzy neural network (EDRFNN) was proposed. The feedback topology of the proposed EDRFNN is fully connected in order to handle temporal pattern behavior. It is constructed from structure and parameter learning. Simulations and comparisons with other recurrent fuzzy neural networks verify the performance of proposed recurrent fuzzy neural network under noisy conditions. In the experiments, other RFNs, including the singleton-type recurrent neural fuzzy network (SRNFN), TS-type RFN (TRFN), and simple RFN (SRFN), are compared. Analysis results indicate that the proposed MDRFN and EDRFNN exhibit excellent classification performance.
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Zhang, Saizheng. "Recurrent neural models and related problems in natural language processing." Thèse, 2019. http://hdl.handle.net/1866/22663.
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Goyette, Kyle. "On two sequential problems : the load planning and sequencing problem and the non-normal recurrent neural network." Thesis, 2020. http://hdl.handle.net/1866/24314.
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The work in this thesis is separated into two parts. The first part deals with the load planning and sequencing problem for double-stack intermodal railcars, an operational problem found at many rail container terminals. In this problem, containers must be assigned to a platform on which the container will be loaded, and the loading order must be determined. These decisions are made with the objective of minimizing the costs associated with handling the containers, as well as minimizing the cost of containers left behind. The deterministic version of the problem can be cast as a shortest path problem on an ordered graph. This problem is challenging to solve because of the large size of the graph. We propose a two-stage heuristic based on the Iterative Deepening A* algorithm to compute solutions to the load planning and sequencing problem within a five-minute time budget. Next, we also illustrate how a Deep Q-learning algorithm can be used to heuristically solve the same problem.The second part of this thesis considers sequential models in deep learning. A recent strategy to circumvent the exploding and vanishing gradient problem in recurrent neural networks (RNNs) is to enforce recurrent weight matrices to be orthogonal or unitary. While this ensures stable dynamics during training, it comes at the cost of reduced expressivity due to the limited variety of orthogonal transformations. We propose a parameterization of RNNs, based on the Schur decomposition, that mitigates the exploding and vanishing gradient problem, while allowing for non-orthogonal recurrent weight matrices in the model.Le travail de cette thèse est divisé en deux parties. La première partie traite du problème de planification et de séquencement des chargements de conteneurs sur des wagons, un problème opérationnel rencontré dans de nombreux terminaux ferroviaires intermodaux. Dans ce problème, les conteneurs doivent être affectés à une plate-forme sur laquelle un ou deux conteneurs seront chargés et l'ordre de chargement doit être déterminé. Ces décisions sont prises dans le but de minimiser les coûts associés à la manutention des conteneurs, ainsi que de minimiser le coût des conteneurs non chargés. La version déterministe du problème peut être formulé comme un problème de plus court chemin sur un graphe ordonné. Ce problème est difficile à résoudre en raison de la grande taille du graphe. Nous proposons une heuristique en deux étapes basée sur l'algorithme Iterative Deepening A* pour calculer des solutions au problème de planification et de séquencement de la charge dans un budget de cinq minutes. Ensuite, nous illustrons également comment un algorithme d'apprentissage Deep Q peut être utilisé pour résoudre heuristiquement le même problème. La deuxième partie de cette thèse examine les modèles séquentiels en apprentissage profond. Une stratégie récente pour contourner le problème de gradient qui explose et disparaît dans les réseaux de neurones récurrents (RNN) consiste à imposer des matrices de poids récurrentes orthogonales ou unitaires. Bien que cela assure une dynamique stable pendant l'entraînement, cela se fait au prix d'une expressivité réduite en raison de la variété limitée des transformations orthogonales. Nous proposons une paramétrisation des RNN, basée sur la décomposition de Schur, qui atténue les problèmes de gradient, tout en permettant des matrices de poids récurrentes non orthogonales dans le modèle.
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Meister, Daniel [Verfasser]. "The complexity of membership problems for finite recurrent systems and minimal triangulations / von Daniel Meister." 2006. http://d-nb.info/981745369/34.
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Bai, You-Chung, and 白有中. "A Recurrent Neural Fuzzy Network with Improved Particle Swarm Optimization for Solving Nonlinear System Control Problems." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/20563612663583550439.
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碩士朝陽科技大學
資訊工程系碩士班
95
In this thesis, we proposed a recurrent neural fuzzy network (RNFN) with improved particle swarm optimization (IPSO) for solving nonlinear system control problem. The RNFN model is a feedforward multi-layer network which integrates traditional Takagi-Sugeno-Kang (TSK) fuzzy model and the wavelet neural networks (WNN). The recurrent property comes from feeding the internal variables, derived from membership function matched degree, back to itself. In the training strategy, we adopt supervised learning method and reinforcement learning method. In the supervised learning method consist of the improved particle swarm optimization (IPSO) and self-organizing improved particle swarm optimization (SOIPSO). The IPSO method which consists of the modified evolutionary direction operator (MEDO) and the particle swarm optimization (PSO). A MEDO combining the evolutionary direction operator (EDO) and the migration operation is also proposed. The MEDO will improve strengthen the global search solution of the evolutionary algorithm. Therefore, we use MEDO enhance PSO for solving nonlinear system control. Moreover, the SOIPSO can determine the fuzzy rules of the recurrent neural fuzzy network and tune the parameters in the RNFN automatically. The structure learning adopts several sub-swarms to constitute variable fuzzy systems and uses an elite-based structure strategy (ESS) to find suitable the number of fuzzy rules. The parameter learning is called an improved particle swarm optimization (IPSO). Although the IPSO and SOIPSO can obtain good performance in the experimental results, however in some real-world applications exact training data may be expensive or even impossible to obtain. To solve this problem, the reinforcement learning method called the reinforcement improved particle swarm optimization (R-IPSO) is proposed. In the R-IPSO, we formulate a number of time steps before failure occurs as the fitness function. The IPSO is used as a way to perform parameter learning. In the experimental results, efficiency of the proposed supervised and reinforcement learning methods are verified from these results.
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Sha, Hao. "Solving Prediction Problems from Temporal Event Data on Networks." Thesis, 2021. http://dx.doi.org/10.7912/C2/46.
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Indiana University-Purdue University Indianapolis (IUPUI)Many complex processes can be viewed as sequential events on a network. In this thesis, we study the interplay between a network and the event sequences on it. We first focus on predicting events on a known network. Examples of such include: modeling retweet cascades, forecasting earthquakes, and tracing the source of a pandemic. In specific, given the network structure, we solve two types of problems - (1) forecasting future events based on the historical events, and (2) identifying the initial event(s) based on some later observations of the dynamics. The inverse problem of inferring the unknown network topology or links, based on the events, is also of great important. Examples along this line include: constructing influence networks among Twitter users from their tweets, soliciting new members to join an event based on their participation history, and recommending positions for job seekers according to their work experience. Following this direction, we study two types of problems - (1) recovering influence networks, and (2) predicting links between a node and a group of nodes, from event sequences.
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Huang, Ching-I., and 黃瀞儀. "Through the Theory of Risk Society to Analyze the problems and Strategies in Recurrent Education in Higher Education in Taiwan." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/48616599713836624850.
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碩士國立中正大學
成人及繼續教育所
94
The research focuses on“risk society”and “the development of macro dimension, meso dimension and micro dimension in recurrent education in higher education in Taiwan ”. And also, the research bases on “risk society”which is advocated by Beck and Giddens. Through the theory to analyze the problems and strategies in recurrent education in higher education in Taiwan. The background of the research is about the transition from Industrial Society to Risk Society. Accordingly, the policies, curriculums and individual learners in the recurrent education in higher education must face many risks and problems. Taken altogether, the purposes of the research is “examine the theory of Risk Society”, “understand the development and comprehension of recurrent education in higher education”, “through the theory of risk society to analyze the risks of the recurrent education in higher education in Taiwan ”and “establish the strategies to solve the risks”. The research uses the method of Theory Analysis and with some discussion and analysis, came to the following conclusions. 1.The theory of Risk Society includes the comprehension of“risk”, “individualization”, and “reflexive modernization”. 2.The theory of Risk Society emphasize “learning reason”, “life narrative ”, and “reflexive learning”. 3.The original of the recurrent education is from Sweden, and the essence emphasize the equality of educational opportunity and learning right. 4.The recurrent education emphasize the learning model of education－work－leisure. 5.The development of the recurrent education in higher education in Taiwan includes protecting the learning right, opening the gat of the recurrent education in higher education, paid education leave, and accreditation of learning achievement. 6.The development of the recurrent education in higher education in Taiwan can generalize 10 phenomenon in the dimensions of policies, curriculums and individual learners. 7.The development of the recurrent education in higher education in Taiwan can generalize 10 risks in the dimensions of policies, curriculums and individual learners. 8.Finally, we can develop 7 strategies to keep off the risks in recurrent education in higher education in Taiwan. Key words:Risk, Risk society, Recurrent Education in Higher Education, Individualization, Reflexive Modernization
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(11048391), Hao Sha. "SOLVING PREDICTION PROBLEMS FROM TEMPORAL EVENT DATA ON NETWORKS." Thesis, 2021.
Find full textAbstract:
Many complex processes can be viewed as sequential events on a network. In this thesis, we study the interplay between a network and the event sequences on it. We first focus on predicting events on a known network. Examples of such include: modeling retweet cascades, forecasting earthquakes, and tracing the source of a pandemic. In specific, given the network structure, we solve two types of problems - (1) forecasting future events based on the historical events, and (2) identifying the initial event(s) based on some later observations of the dynamics. The inverse problem of inferring the unknown network topology or links, based on the events, is also of great important. Examples along this line include: constructing influence networks among Twitter users from their tweets, soliciting new members to join an event based on their participation history, and recommending positions for job seekers according to their work experience. Following this direction, we study two types of problems - (1) recovering influence networks, and (2) predicting links between a node and a group of nodes, from event sequences.
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Chen, Muye. "Vanishing Gradient Problem in Training Neural Networks." Thesis, 2022. http://hdl.handle.net/1885/268662.
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The Vanishing Gradient Problem (VGP) is a frequently encountered numerical problem in training Feedforward Neural Networks (FNN) and Recurrent Neural Networks (RNN). The gradient involved in neural network optimisation can vanish and become zero in a number of ways. In this thesis we focus on the following definition of the VGP: the tendency for network loss gradients, calculated with respect to the model weight parameters, to vanish numerically in the back propagation step of network training. Due to the differences in data types on which the two types of networks are trained, the model architectures are different. Consequently the methods to alleviate the problem take different forms and focus on different model components. This thesis attempts to introduce basic neural network model architectures to readers who are new to deep learning and using neural networks, with a particular focus on how the VGP can affect the model performance. We conduct the relevant research of RNNs in the context of a simple classification task in the field of Natural Language Processing (NLP). We have im- implemented and analysed the existing solutions to the VGP through mathematical details and graphical results from experiments. The thesis is extended to two types of advanced RNN-class models which are designed to be resistant to the VGP. However our experimental results reveal that under a strict indicator, the two advanced models instead exhibit stronger tendency of the VGP, than the standard RNN model does. With regards to this finding, we introduce a different viewpoint proposed by Rehmer & Kroll (2020) regarding the VGP in RNN-class models, which support our results. We have discussed its relevance to our experiments and extended their derivations to another RNN-class model they have not covered.
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Chin, Tai-Lin, and 金台齡. "On the Time Scheduling Problem of Uniform Recurrence Equations." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/44704529731090887534.
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碩士國立交通大學
資訊工程學系
85
In this thesis, we study a series of hyperplane-based time scheduling methods for uniform recurrence equations. The studied schedules are linear schedule, uniform affine schedule, affine schedule, and multi-dimensional schedule.In addition, a schedule named as multi-dimensional affine schedule is studied.It improves the execution time of the multi-dimensional schedule. All these scheduling problems are formulated as linear programs. Time scheduling problem is a very important problem on parallel cmputing field. It plays an important role in the designs of parallel processor array and parallel compilers. Besides, for illustration, these scheduling methods are implemented for some real examples, including convolution, selection sort, 2D filter and a complex example of uniform recurrence equations. From these illustrative examples, the quality of various time scheduling methods can be explored. Moreover, the importance of the time scheduling problem in parallel algorithms can be seen.
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Kanuparthi, Bhargav. "Towards better understanding and improving optimization in recurrent neural networks." Thesis, 2020. http://hdl.handle.net/1866/24319.
Full textAbstract:
Recurrent neural networks (RNN) are known for their notorious exploding and vanishing gradient problem (EVGP). This problem becomes more evident in tasks where the information needed to correctly solve them exist over long time scales, because it prevents important gradient components from being back-propagated adequately over a large number of steps. The papers written in this work formalizes gradient propagation in parametric and semi-parametric RNNs to gain a better understanding towards the source of this problem. The first paper introduces a simple stochastic algorithm (h-detach) that is specific to LSTM optimization and targeted towards addressing the EVGP problem. Using this we show significant improvements over vanilla LSTM in terms of convergence speed, robustness to seed and learning rate, and generalization on various benchmark datasets. The next paper focuses on semi-parametric RNNs and self-attentive networks. Self-attention provides a way by which a system can dynamically access past states (stored in memory) which helps in mitigating vanishing of gradients. Although useful, it is difficult to scale as the size of the computational graph grows quadratically with the number of time steps involved. In the paper we describe a relevancy screening mechanism, inspired by the cognitive process of memory consolidation, that allows for a scalable use of sparse self-attention with recurrence while ensuring good gradient propagation.Les réseaux de neurones récurrents (RNN) sont connus pour leur problème de gradient d'explosion et de disparition notoire (EVGP). Ce problème devient plus évident dans les tâches où les informations nécessaires pour les résoudre correctement existent sur de longues échelles de temps, car il empêche les composants de gradient importants de se propager correctement sur un grand nombre d'étapes. Les articles écrits dans ce travail formalise la propagation du gradient dans les RNN paramétriques et semi-paramétriques pour mieux comprendre la source de ce problème. Le premier article présente un algorithme stochastique simple (h-detach) spécifique à l'optimisation LSTM et visant à résoudre le problème EVGP. En utilisant cela, nous montrons des améliorations significatives par rapport au LSTM vanille en termes de vitesse de convergence, de robustesse au taux d'amorçage et d'apprentissage, et de généralisation sur divers ensembles de données de référence. Le prochain article se concentre sur les RNN semi-paramétriques et les réseaux auto-attentifs. L'auto-attention fournit un moyen par lequel un système peut accéder dynamiquement aux états passés (stockés en mémoire), ce qui aide à atténuer la disparition des gradients. Bien qu'utile, il est difficile à mettre à l'échelle car la taille du graphe de calcul augmente de manière quadratique avec le nombre de pas de temps impliqués. Dans l'article, nous décrivons un mécanisme de criblage de pertinence, inspiré par le processus cognitif de consolidation de la mémoire, qui permet une utilisation évolutive de l'auto-attention clairsemée avec récurrence tout en assurant une bonne propagation du gradient.
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Lemańczyk, Michał. "Recurrence of stochastic processes in some concentration of measure and entropy problems." Doctoral thesis, 2022. https://depotuw.ceon.pl/handle/item/4158.
Full textAbstract:
Let X = (Xi)i∈Z, where Xi ∈ X and X is a (measurable) state space, be a stochastic process. The
thesis is focused on the role played by the return time process R = (Ri)i∈Z of consecutive return
times of X to some prescribed subset of X Z, both in probability and in ergodic theory. In the most
simple case, given A ⊂ X , the corresponding return time process is de ned as
Ri =
inf{j ≥ 0 : Xj ∈ A}, i = 0,
inf{j > Ri−1 : Xj ∈ A}, i ≥ 1,
sup{j < Ri+1 : Xj ∈ A}, i ≤ −1.
(1.1)
The main result on the probability side is proving a Bernstein inequality for additive functionals of
general not necessarily strongly aperiodic Markov chains (see [A3]), thus answering an open question
from [1]. We also prove a new version of the Bernstein inequality for 1-dependent processes (this class
is strongly related to Markov chains due to the regeneration technique). On the ergodic theory side, the
main results contain explicit formulas and estimates for the entropy rate of coordinatewise products of
processes (see [A1]). This, in turn, serves as a tool in solving several problems. We give a new explicit
formula for the topological pressure of BBB-free systems (for short BFSs). We prove the uniqueness of
equilibrium measures for BFSs for potentials depending on one coordinate (thus extending the result
on the intrinsic ergodicity from [3, 2]). At last, we answer open questions on the entropy of BFSs
from [2] (see [A1]) and we show that the measure of maximal entropy does not satisfy the Gibbs
property (see [A2]) which answers the question posed by Peckner in [3].
Part of the material included in this thesis is new, part of it is based on the following three articles:
[A1] J. Kuªaga-Przymus and M.D. Lema«czyk. Entropy rate of product of independent processes.
Preprint: arXiv:2004.07648, 2020.
[A2] J. Kuªaga-Przymus and M.D. Lema«czyk. Hereditary subshifts whose measure of maximal en-
tropy has no Gibbs property. To appear in Colloquium Mathematicum, arXiv:2004.07643, 2020.
[A3] M.D. Lema«czyk. General Bernstein-like inequality for additive functionals of Markov chains.
Journal of Theoretical Probability, 2020.Niech X = (Xi)i∈Z, gdzie Xi ∈ X a X jest (mierzaln¡) przestrzeni¡ stanów, b¦dzie procesem stochasty- cznym. Niniejsza rozprawa doktorska koncentruje si¦ na procesach czasów powrotu R = (Ri)i∈Z kolejnych powrotów Xi do A oraz ich roli zarówno w teorii prawdopodobie«stwa, jak i w teorii ergody- cznej. Przypomnijmy, »e dla danego podzbioru A ⊂ X odpowiadaj¡cy mu proces czasów powrotu jest zde niowany jako Ri = inf{j ≥ 0 : Xj ∈ A}, i = 0, inf{j > Ri−1 : Xj ∈ A}, i ≥ 1, sup{j < Ri+1 : Xj ∈ A}, i ≤ −1. (1.1) Gªównym rezultatem rozprawy w teorii prawdopodobie«stwa jest dowód nierówno±ci Bernsteina dla funkcjonaªów addytywnych ogólnych, niekoniecznie silnie aperiodycznych, ªa«cuchów Markowa, co daje odpowied¹ na pytanie sformuªowane w pracy [1] (patrz [A3]). Dowodzimy równie» pewnej nowej wersji nierówno±ci Bernsteina dla 1-zale»nych procesów (klasa ta jest silnie zwi¡zana z ªa«cuchami Markowa dzi¦ki tzw. technice regeneracji). Gªówne rezultaty w teorii ergodycznej dotycz¡ dokªadnych wzorów, b¡d¹ nierówno±ci, zwi¡zanych z entropi¡ (ang. entropy rate) punktowego iloczynu procesów (patrz [A1]). Staj¡ si¦ one narz¦dziem do rozwi¡zania kilku otwartych problemów. Podajemy nowy, jawny wzór na ci±nienie topologiczne ukªadów BBB-wolnych oraz, w pewnych przypadkach, dowodzimy jedyno±ci stanów równowagi dla ukªadu wyznaczonego przez BBB (co rozszerza rezultaty o wewn¦trznej ergodyczno±ci udowodnione w [3, 2]). Odpowiadamy na pytanie postawione w [3] o braku wªasno±ci Gibbsa dla miary o maksymalnej entropii (patrz [A2]). W ko«cu, odpowiadamy na kilka pyta« doty- cz¡cych entropii ukªadów BBB-wolnych z pracy [2] (patrz [A1]). Cz¦±¢ rezultatów rozprawy jest nowa, pozostaªe rezultaty pochodz¡ z nast¦puj¡cych trzech artykuªów: [A1] J. Kuªaga-Przymus and M.D. Lema«czyk. Entropy rate of product of independent processes. Preprint: arXiv:2004.07648, 2020. [A2] J. Kuªaga-Przymus and M.D. Lema«czyk. Hereditary subshifts whose measure of maximal en- tropy has no Gibbs property. To appear in Colloquium Mathematicum, arXiv:2004.07643, 2020. [A3] M.D. Lema«czyk. General Bernstein-like inequality for additive functionals of Markov chains. Journal of Theoretical Probability, 2020.
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Liao, Jian-Wei, and 廖建維. "An Ensemble Learning Approach for Data Stream with Concept Drift and Recurring Class Problem." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/39769659102476301628.
Full textAbstract:
碩士國立臺灣科技大學
資訊工程系
102
Recently, concept drift has become an important issue while analyzing non-stationary distribution data in data mining. For example, data streams carry a characteristic that data vary by time, and there is probably concept drift in this type of data. Concept drifts can be categorized into sudden and gradual concept drifts in brief. Most of researches concentrate on solving one type of concept drift since the type of concept drift is usually difficult to be identified. Moreover, there is an important issue in the data stream called recurring class problem which is caused by concept drift. This problem often occurs in the non-stationary environment. In light of these reasons, we propose two new weighting mechanisms to base models in the ensemble and new arriving data in order to adapt to current concept quickly. The experimental results show that our method is not only stable enough on the datasets with gradual concept drifts but also flexible to adapt to sudden concept drifts and the recurring class problem.
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Senna, Daniel Lordêllo. "O Estatuto do Árbitro Numa Perspectiva De Direito Comparado Entre Portugal e Brasil." Master's thesis, 2017. http://hdl.handle.net/10316/84014.
Full textAbstract:
Dissertação de Mestrado em Direito: Especialidade em Ciências Juridico-Forenses apresentada à Faculdade de DireitoO Estatuto do Árbitro Numa Perspectiva De Direito Comparado Entre Portugal e Brasil.O árbitro é figura central do instituto da arbitragem, e, neste trabalho, procurou-se enfatizar a importância da sua atuação para o crescimento desta forma alternativa de solução de litígios, com especial ênfase nos ordenamentos português e brasileiro.Verificou-se uma série de problemas e dificuldades às quais estão os árbitros submetidos ao cumprirem a sua função, especialmente aqueles relacionados à questão de quem pode exercer o encargo, os deveres inerentes à investidura e principalmente os atributos da independência e imparcialidade.Na mesma esteira, não se deixou de analisar os direitos dos árbitros e demais partes envolvidas na arbitragem. Questões controvertidas na jurisprudência foram analisadas, especialmente aquelas atinentes à recusa do árbitro e o dever de revelação, problemas que claramente predominam entre as intempéries às quais está exposta a arbitragem.O presente trabalho contém, ainda, uma sugestão de alteração nas legislações portuguesa e brasileira, para que se passe a exigir a presença de ao menos um jurista na constituição do tribunal arbitral, com o objetivo de fazer reduzir o número de incidentes trazidos por algum desconhecimento da matéria legal dos árbitros e seu estatuto.Frise-se que tal exigência já existe na legislação espanhola e em diversos outros países hispano-americanos. Resta claro que esta proposta passa longe de ser inatacável ou livre de críticas, posto que boa parte da doutrina defende que tal alteração seria antidemocrática, corporativista e protecionista.Contudo, observa-se que os problemas que envolvem a arbitragem no Brasil e em Portugal, estão, em grande medida, relacionados à falta de conhecimento, por parte dos árbitros não juristas, de premissas básicas e basilares do direito, nomeadamente questões que envolvem a independência e imparcialidade como condição precípua para o exercício da função, afinal, tais atributos são fundamento da legitimidade do poder de julgar. Também importante é a discussão que se trava na jurisprudência portuguesa acerca do grau de fundamentação da sentença arbitral. Há acórdãos recentes em que se percebe a absoluta discrepância entre os entendimentos acerca da matéria.Aqui se defendeu o entendimento de que há rigor excessivo por parte dos juízes dos tribunais estaduais e que tal exigência acaba por abrir flancos indesejáveis a ações anulatórias que, em última análise, enfraquecem o instituto da arbitragem.
The statute of the arbitrator in a comparative law perspective between Portugal and Brazil.The arbitrator is a central figure of the arbitration institute and, in this work, we tried to emphasize the importance of its action for the growth of this alternative form of dispute settlement, with special emphasis on Portuguese and Brazilian law.There have been a number of problems and difficulties to which the arbitrators are subjected in carrying out their duties, especially those related to the question of who can perform the task, the duties inherent to the investiture, and especially the attributes of independence and impartiality.In the same vein, the rights of the arbitrators and other parties involved in the arbitration were also examined. Controversial issues in the case-law have been examined, especially those concerning refusal by the arbitrator and the duty to disclose, problems which clearly prevail among the weather to which arbitration is exposed.The present work also contains a suggestion of alteration in Portuguese and Brazilian legislation, so that it is necessary to have at least one jurist present in the constitution of the arbitral tribunal, in order to reduce the number of incidents brought about by some unknown Of the legal matter of the arbitrators and their status.It is frightened that such a requirement already exists in Spanish law and in several other Spanish-American countries. It remains clear that this proposal is far from being unassailable or free from criticism, since much of the doctrine holds that such a change would be undemocratic, corporatist and protectionist.However, it is observed that the problems involving arbitration in Brazil and Portugal are, to a large extent, related to the lack of knowledge by non-legal arbitrators of basic and basic premises of law, namely issues involving Independence and impartiality as the precondition for the exercise of the function, after all, such attributes are the basis of the legitimacy of the power to judge.Also important is the discussion in Portuguese jurisprudence about the degree of justification of the arbitration award. There are recent judgments in which the absolute discrepancy between the understandings about the matter is perceived.Here it was defended the understanding that there is excessive rigor on the part of the judges of the state courts and that this requirement ends up opening undesirable flanks to annulatory actions that, in the end, weaken the institute of the arbitration.
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Beauregard, Julie. "Trajectoires et profils des adolescents placés en centre de réadaptation présentant des troubles de comportement sérieux." Thèse, 2018. http://hdl.handle.net/1866/21339.
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