O crescimento do uso de sistemas de posicionamento global (GPS) e outros sistemas de localização espacial tornaram possível o rastreamento de objetos móveis, produzindo um grande volume de um novo tipo de dado, chamado trajetórias de objetos móveis. Existe, entretanto, uma forte lacuna entre a quantidade de dados extraídos destes dispositivos, dotados de sistemas GPS, e a descoberta de conhecimento que se pode inferir com estes dados. Um tipo de descoberta de conhecimento em dados de trajetórias de objetos móveis é a classificação. A classificação de trajetórias é um tema de pesquisa relativamente novo, e poucos métodos tem sido propostos até o presente momento. A maioria destes métodos foi desenvolvido para uma aplicação específica. Poucos propuseram um método mais geral, aplicável a vários domínios ou conjuntos de dados. Este trabalho apresenta um novo método de classificação que transforma as trajetórias em séries temporais, de forma a obter características mais discriminativas para a classificação. Experimentos com dados reais mostraram que o método proposto é melhor do que abordagens existentes. / The growing use of global positioning systems (GPS) and other location systems made the tracking of moving objects possible, producing a large volume of a new kind of data, called trajectories of moving objects. However, there is a large gap between the amount of data generated by these devices and the knowledge that can be inferred from these data. One type of knowledge discovery in trajectories of moving objects is classification. Trajectory classification is a relatively new research subject, and a few methods have been proposed so far. Most of these methods were developed for a specific application. Only a few have proposed a general method, applicable to multiple domains or datasets. This work presents a new classification method that transforms the trajectories into time series, in order to obtain more discriminative features for classification. Experiments with real trajectory data revealed that the proposed approach is more effective than existing approaches.

A presente tese analisa a maneira como a probabilidade influencia a formação da decisão sobre os fatos (contexto de descobrimento), bem como a motivação acerca dessas decisões (contexto justificativo). Mediante prévia análise da relevância da verdade no processo judicial, demonstra-se também que no terreno processual somente é possível falar em probabilidade, o que implica a ideia de um modelo probabilístico do juízo de fato, cujo núcleo é o módulo da escolha entre as alternativas possíveis. Portanto, são oferecidos critérios para a escolha das alternativas, os quais são denominados como diretrizes probatórias. De outro lado, a fim de que o convencimento do juiz a respeito dos fatos seja o mais racional possível, também é examinada a obrigatoriedade da motivação das decisões judiciais. Para tanto, é realizada abordagem à luz do Estado Constitucional e, ao final, demonstra-se que a probabilidade igualmente conforma o contexto justificativo, pois faz com que a motivação seja um discurso probatório racional. / This thesis examines how probability influences the fact-finding process (context of discovery) and the motivation about the trial of facts (context of justification). Considering the analysis of the relevance of truth in the judicial process, also in the procedural field only probability is taken into account, which implies the idea of a probabilistic model of factual judgment, whose core is the module of choice among the possible alternatives. Therefore, guidelines are offered for the choice of alternatives, which are called as evidentiary guidelines. On the other hand, in order to achieve the most rational conviction of the trier, mandatory legal motivation is also examined. The approach focuses on the Constitutional State and, in the end, is shown that the probability also conforms the context of justification, in order to make the legal motivation as a rational evidence speech.

This thesis consists of three essays examining the impact and consequences of the trading behaviour of a finely disaggregated category of investors in an electronic limit order book equity market, the Malta Stock Exchange (MSE). The three essays in market microstructure are closely related and examine how investor heterogeneity impacts the informational content of the limit order book, the informational content of individual trades, the price impact of investor trades, the aggressiveness of order submission strategies and the price discovery process within such a market. The first essay investigates the role of the financial intermediary in the price discovery process in a limit order market. We address this issue by analysing the trades of brokers within the Malta Stock Exchange by comparing the profitability of their individual trades and the impact of these trades on the price discovery process. The results of a Weighted Price Contribution methodology indicate that more active brokers that dominate the market in terms of volume and amount traded account for a significant portion of the price discovery process. We also find that the level of profitability of these brokers is directly proportional to the amount of volume traded and their relative share in the price discovery process. This appears to rule out the possibility of manipulative trades by these brokers in order to influence profitabilityThe second essay examines the price impact of the order flow emanating from finely disaggregated classes of investor with the aim of determining whether detectable differences exist in the extent to which orders emanating from particular groups of investors impact on the evolution of stock prices. On the aggregate stock level, results indicate price impact is inversely related to liquidity and as such the price impact of trades is of a higher magnitude and significance in stocks that are less liquid. Significantly, we find that stocks with higher liquidity and trading volume adjust quickly to price changes and the cumulative impact is realised earlier for these stocks. Similarly, for investor classes, our results show that the magnitude and significance of individual price impact increases as liquidity of the stocks declines, showing that as liquidity increases in the order book, the impact of information asymmetry begins to diminish. Institutional investors consistently have the highest significant impact on the evolution of prices across all the stocks. The final essay examines how investors structure their order submission choice in response to changes in the limit order book and market conditions (such as order depth, volatility, returns, and height of the limit order book). We identify 7 distinct investor classes who differ in their trading requirement and the information set available to them, and as such we expect that these investors will adopt different strategies to maximise their trades. The results show variability in the submission strategies adopted by investors as trade sides changes from buy to sell trades. It also indicate that investors have to balance between execution risk, the timely use of private information and the risk of being picked-off by other informed investors. In analysing the varied responses of these investors, we find that the order submission strategies adopted is most responsive to the risk of non-execution.

The Internet has evolved into a medium centered around content: people watch videos on YouTube, share their pictures via Flickr, and use Facebook to keep in touch with their friends. Yet, the only globally deployed service to discover content - i.e., Domain Name System (DNS) - does not discover content at all; it merely translates domain names into locations. The lack of persistent naming, in particular, makes content discovery, instead of domain discovery, challenging. Content Distribution Networks (CDNs), which augment DNSs with location-awareness, also suffer from the same problem of lack of persistent content names. Recently, several infrastructure- level solutions to this problem have emerged, but their fundamental limitation is that they fail to preserve the autonomy of network participants. Specifically, the storage requirements for resolution within each participant may not be proportional to their capacity. Furthermore, these solutions cannot be incrementally deployed. To the best of our knowledge, content discovery services based on peer-to-peer (P2P) networks are the only ones that support persistent content names. These services also come with the built-in advantage of scalability and deployability. However, P2P networks have been deployed in the real-world only recently, and their real-world characteristics are not well understood. It is important to understand these real-world characteristics in order to improve the performance and propose new designs by identifying the weaknesses of existing designs. In this dissertation, we first propose a novel, lightweight technique for capturing P2P traffic. Using our captured data, we characterize several aspects of P2P networks and draw conclusions about their weaknesses. Next, we create a botnet to demonstrate the lethality of the weaknesses of P2P networks. Finally, we address the weaknesses of P2P systems to design a P2P-based content discovery service, which resolves the drawbacks of existing content discovery systems and can operate at Internet-scale. This dissertation includes both previously published/unpublished and co-authored material.

As estrategias de passes têm sido sempre de interesse para a pesquisa de futebol. Desde os inícios do futebol, os técnicos tem usado olheiros, gravações de vídeo, exercícios de treinamento e feeds de dados para coletar informações sobre as táticas e desempenho dos jogadores. No entanto, a natureza dinâmica das estratégias de passes são bastante complexas para refletir o que está acontecendo dentro do campo e torna difícil o entendimento do jogo. Além disso, existe uma demanda crecente pela deteção de padrões e analise de estrategias de passes popularizado pelo tiki-taka utilizado pelo FC. Barcelona. Neste trabalho, propomos uma abordagem para abstrair as sequências de pases e agrupálas baseadas na geometria da trajetória da bola. Para analizar as estratégias de passes, apresentamos um esquema de visualização interátiva para explorar a frequência de uso, a localização espacial e ocorrência temporal das sequências. A visualização Frequency Stripes fornece uma visão geral da frequencia dos grupos achados em tres regiões do campo: defesa, meio e ataque. O heatmap de trajetórias coordenado com a timeline de passes permite a exploração das formas mais recorrentes no espaço e tempo. Os resultados demostram oito trajetórias comunes da bola para sequências de três pases as quais dependem da posição dos jogadores e os ângulos de passe. Demonstramos o potencial da nossa abordagem com utilizando dados de várias partidas do Campeonato Brasileiro sob diferentes casos de estudo, e reportamos os comentários de especialistas em futebol. / Passing strategies analysis has always been of interest for soccer research. Since the beginning of soccer, managers have used scouting, video footage, training drills and data feeds to collect information about tactics and player performance. However, the dynamic nature of passing strategies is complex enough to reflect what is happening in the game and makes it hard to understand its dynamics. Furthermore, there exists a growing demand for pattern detection and passing sequence analysis popularized by FC Barcelona’s tiki-taka. We propose an approach to abstract passing strategies and group them based on the geometry of the ball trajectory. To analyse passing sequences, we introduce a interactive visualization scheme to explore the frequency of usage, spatial location and time occurrence of the sequences. The frequency stripes visualization provide, an overview of passing groups frequency on three pitch regions: defense, middle, attack. A trajectory heatmap coordinated with a passing timeline allow, for the exploration of most recurrent passing shapes in temporal and spatial domains. Results show eight common ball trajectories for three-long passing sequences which depend on players positioning and on the angle of the pass. We demonstrate the potential of our approach with data from the Brazilian league under several case studies, and report feedback from a soccer expert.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A tese pretende estabelecer o que estaria o mais próximo possível de uma lógica da descoberta para as ciências sociais. A narrativa dessas disciplinas não seria neutra nem objetiva, mas procuraria produzir, retoricamente, os efeitos de neutralidade e objetividade, evitando a heroicização, a vilanização e a vitimização dos agentes. Isso decorreria da necessidade de o cientista social validar sua narrativa perante um auditório ideal ou potencialmente universal, abrigando, em princípio, todo o tipo de valores. Essa pluralidade de visões de mundo não permite que os agentes sejam ingenuamente tratados como heróis, vilões ou vítimas. Com isso, o autor do texto de ciências sociais procuraria simular um ponto de vista de Deus, como ironista supremo, que tudo vê, acima dos participantes imperceptivos de seu relato. Foi feito um estudo de caso a partir do debate sobre populismo no Brasil, no qual foram identificados quatro pontos básicos em torno dos quais girou a controvérsia: o das estruturas prototípicas, o da estruturação imaginária, o da estrutura intersubjetiva e a dinâmica da relação entre grande teoria e pesquisa empírica. / The aim of this thesis is to get as close as possible to a logic of discovery for the social sciences. Those disciplines do not have a neutral and objective narrative, but try to achieve, rhetorically, neutrality and objectivity effects, avoiding to portrait agents as heroes, villains or victims. It follows from the need to validate scientific narratives in face of an ideally or potentially universal auditory, withholding, in principle, all kinds of values. Such plurality of world visions makes it difficult to naively treat agents as heroes, villains, or victims. As a consequence, the social scientist simulates a Gods Eye view, placing himself in a Supreme Ironist perspective, who sees everything from above, whose vision reaches beyond what nonperceptive agents can see. To make my point, I took as case study the Brazilian controversy over populism. Based on it, four main topics of development were identified: one refered to the prototypical theoretic structures, other to its imaginary structuration, another to its intersubjective structure, and a last one to the relationship of empirical research to grand theory.

Aplicações cientes de contexto precisam de mecanismos para recuperar informações sobre o seu contexto de execução. Com base no contexto atual, tais aplicações são capazes de se autoadaptar para fornecer informações e serviços adequados aos seus usuários. A abordagem comum para infraestruturas de apoio às aplicações sensíveis ao contexto fornece serviços para a descoberta de recursos através da utilização de pares <chave-valor> e motores que executam apenas correspondência sintática. Esta abordagem não considera as possíveis relações semânticas entre as palavras-chave usadas. Portanto, a sua expressividade semântica limitada, leva a um serviço de descoberta que provê baixa taxa de recuperação e baixa acurácia. Este trabalho apresenta a utilização de uma outra abordagem para o serviço de contexto e descoberta, que utiliza ontologias para representar os recursos do contexto de execução e capturar a semântica da consulta do usuário, melhorando assim o processo de descoberta para a autoadaptação de sistemas sensíveis ao contexto. A abordagem proposta oferece também pontos de extensão para as aplicações clientes através da utilização de outras ontologias. Esta abordagem foi integrada à infraestrutura CDRF, de forma a adicionar semântica aos serviços desenvolvidos neste projeto. Exemplos de aplicações são também propostos para demonstrar a utilização dos novos serviços. / Context-aware applications demand ways of retrieving context information from the environment. Based on the current context, such applications are able to self-adapt to provide the correct information and services to its users. The usual approach for supporting infrastructures for context-aware applications provides facilities for resource discovery using <key-value> pairs and discovery engines that perform syntactic matching. This approach does not consider the possible semantic relations between the keywords used. So its limited semantic expressiveness often leads to poor discovery results. This paper presents the use of a different approach for service discovery that uses ontologies to represent resources and capture the semantics of the users query, improving the discovery process for self-adaptation of context-aware systems. The proposed approach also offers extension hooks to the client applications through the use of other ontologies. This approach is integrated into the CDRF framework and adds semantics to the services developed in that project. Example applications are also proposed to demonstrate the use of the new services.

Atualmente, técnicas de recuperação e análise de informações, principalmente textuais, são de extrema importância. Após o grande BOOM da Internet, muitos problemas que já eram conhecidos em contextos fechados passaram a preocupar também toda a comunidade científica. No âmbito deste trabalho os problemas relacionados à sobrecarga de informações, que ocorre devido ao grande volume de dados a disposição de uma pessoa, são os mais importantes. Visando minimizar estes problemas, este trabalho apresenta um estudo sobre métodos de agrupamento de objetos textuais (documentos no formato ASCII), onde os objetos são organizados automaticamente em grupos de objetos similares, facilitando sua localização, manipulação e análise. Decorrente deste estudo, apresenta-se uma metodologia de aplicação do agrupamento descrevendo-se suas diversas etapas. Estas etapas foram desenvolvidas de maneira que após uma ter sido realizada ela não precisa ser refeita, permitindo que a etapa seguinte seja aplicada diversas vezes sobre os mesmos dados (com diferentes parâmetros) de forma independente. Além da metodologia, realiza-se um estudo comparativo entre alguns algoritmos de agrupamento, inclusive apresentando-se um novo algoritmo mais eficiente. Este fato é comprovado em experimentos realizados nos diversos estudos de caso propostos. Outras contribuições deste trabalho incluem a implementação de uma ferramenta de agrupamento de textos que utiliza a metodologia elaborada e os algoritmos estudados; além da utilização de uma fórmula não convencional de cálculo de similaridades entre objetos (de abordagem fuzzy), aplicada a informações textuais, obtendo resultados satisfatórios. / The Internet is the vital media of today and, as being a mass media, problems known before to specific fields of Science arise. One of these problems, capable of annoying many people, is the information overload problem caused by the excessive amount of information returned in response to the user’s query. Due to the information overload problem, advanced techniques for information retrieval and analysis are needed. This study presents some aids in these fields, presenting a methodology to help users to apply the clustering process in textual data. The technique investigated is capable of grouping documents of several subjects in clusters of documents of the same subject. The groups identified can be used to simplify the process of information analysis and retrieval. This study also presents a tool that was created using the methodology and the algorithms analyzed. The tool was implemented to facilitate the process of investigation and demonstration of the study. The results of the application of a fuzzy formula, used to calculate the similarity among documents, are also presented.

Social entrepreneurship (SE) has become a rapidly advancing domain of enquiry and holds a place in policy makers consideration around the globe. Opportunities have been regarded as critical in SE, but are often portrayed in abstract and unspecified ways. Research on this topic remains relatively scarce, theory building is not yet established and integrated, and the dearth of empirical studies further constrains theoretical development in SE. Researchers have thus called for more exploration and a comprehensive theoretical understanding of SE opportunities. The purpose of this study is to explore SE opportunities through empirical investigation and theoretical development. As an exploratory study, this study addresses two broad research questions: (1) What are SE opportunities? And (2) How do they emerge? To answer these questions, I draw on the broader entrepreneurship literature which provides two main alternative explanations: opportunity discovery (nexus theory) and opportunity creation (effectuation theory). While the discovery/creation debate is still ongoing, recent theoretical advancement has shown a possible path of forwarding entrepreneurial opportunity research, suggesting that research should incorporate structure and agency simultaneously in studying opportunities. Following this path, this study contributes to SE opportunity research by providing a comprehensive understanding of SE opportunities, it also helps address the discovery/creation debate in the context of SE. To make this contribution, this study first adopts critical realism as a research philosophy as well as methodology. Critical realism incorporates the effects of both structure and agency through its ontological assumptions of three domains of reality, while providing an explanatory framework to assess competing theories. Second, this study selects China as a context for empirical study. As a relation-oriented society, China provides a useful context for studying the causal relations between the social structure (guanxi) and SE opportunity. China s institutional context and fast growing social enterprise sector also provides a promising setting for exploratory research on SE opportunities. Based on critical realism, I used a three-step qualitative multi-case study to develop an explanatory framework in which guanxi and social capital theory provide theoretical explanations of the social structure and its causal powers, which lead to SE opportunity emergence in China. Data were collected from 45 interviews with Chinese social entrepreneurs, their employees and other key stakeholders in 36 organisations in Beijing, Hunan Province and Shanghai. My research findings show that SE opportunities develop in all of the three domains defined by critical realism. In the domain of empirical a world of human experience of social events a SE opportunity can be described as discovered, created, or as both discovered and created. In the domain of actual the social events under study a SE opportunity consists of three internal and necessary constituents: unjust social equilibrium (USE), social entrepreneurs beliefs (SEB), and social feasibility (SF). In the domain of real deeper structures, causal powers and mechanism that produce the social event the emergence of SE opportunities can be seen as the result of a resource acquisition and mobilisation mechanism whereby USE, SEB and SF are identified or formed through social entrepreneurs social capital embedded in guanxi. Building on these findings, this study concludes with a theoretical framework that offers a comprehensive explanation of SE opportunity emergence in China. This study is the first attempt to apply critical realism to the study of opportunities in the context of SE in China. It contributes to the SE and general entrepreneurship literature by developing a theoretical framework of SE opportunity emergence that provides an alternative explanation for the existence of discovery and creation opportunities, and by extending our theoretical understandings of some key concepts of SE. This research further provides an example of the use of qualitative methods to apply critical realism in SE and general entrepreneurship research, which contributes to the development of relatively rigorous research design and research methods in studying complex social events.

Atualmente, técnicas de recuperação e análise de informações, principalmente textuais, são de extrema importância. Após o grande BOOM da Internet, muitos problemas que já eram conhecidos em contextos fechados passaram a preocupar também toda a comunidade científica. No âmbito deste trabalho os problemas relacionados à sobrecarga de informações, que ocorre devido ao grande volume de dados a disposição de uma pessoa, são os mais importantes. Visando minimizar estes problemas, este trabalho apresenta um estudo sobre métodos de agrupamento de objetos textuais (documentos no formato ASCII), onde os objetos são organizados automaticamente em grupos de objetos similares, facilitando sua localização, manipulação e análise. Decorrente deste estudo, apresenta-se uma metodologia de aplicação do agrupamento descrevendo-se suas diversas etapas. Estas etapas foram desenvolvidas de maneira que após uma ter sido realizada ela não precisa ser refeita, permitindo que a etapa seguinte seja aplicada diversas vezes sobre os mesmos dados (com diferentes parâmetros) de forma independente. Além da metodologia, realiza-se um estudo comparativo entre alguns algoritmos de agrupamento, inclusive apresentando-se um novo algoritmo mais eficiente. Este fato é comprovado em experimentos realizados nos diversos estudos de caso propostos. Outras contribuições deste trabalho incluem a implementação de uma ferramenta de agrupamento de textos que utiliza a metodologia elaborada e os algoritmos estudados; além da utilização de uma fórmula não convencional de cálculo de similaridades entre objetos (de abordagem fuzzy), aplicada a informações textuais, obtendo resultados satisfatórios. / The Internet is the vital media of today and, as being a mass media, problems known before to specific fields of Science arise. One of these problems, capable of annoying many people, is the information overload problem caused by the excessive amount of information returned in response to the user’s query. Due to the information overload problem, advanced techniques for information retrieval and analysis are needed. This study presents some aids in these fields, presenting a methodology to help users to apply the clustering process in textual data. The technique investigated is capable of grouping documents of several subjects in clusters of documents of the same subject. The groups identified can be used to simplify the process of information analysis and retrieval. This study also presents a tool that was created using the methodology and the algorithms analyzed. The tool was implemented to facilitate the process of investigation and demonstration of the study. The results of the application of a fuzzy formula, used to calculate the similarity among documents, are also presented.