abstract: Answer Set Programming (ASP) is one of the main formalisms in Knowledge Representation (KR) that is being widely applied in a large number of applications. While ASP is effective on Boolean decision problems, it has difficulty in expressing quantitative uncertainty and probability in a natural way. Logic Programs under the answer set semantics and Markov Logic Network (LPMLN) is a recent extension of answer set programs to overcome the limitation of the deterministic nature of ASP by adopting the log-linear weight scheme of Markov Logic. This thesis investigates the relationships between LPMLN and two other extensions of ASP: weak constraints to express a quantitative preference among answer sets, and P-log to incorporate probabilistic uncertainty. The studied relationships show how different extensions of answer set programs are related to each other, and how they are related to formalisms in Statistical Relational Learning, such as Problog and MLN, which have shown to be closely related to LPMLN. The studied relationships compare the properties of the involved languages and provide ways to compute one language using an implementation of another language. This thesis first presents a translation of LPMLN into programs with weak constraints. The translation allows for computing the most probable stable models (i.e., MAP estimates) or probability distribution in LPMLN programs using standard ASP solvers so that the well-developed techniques in ASP can be utilized. This result can be extended to other formalisms, such as Markov Logic, ProbLog, and Pearl’s Causal Models, that are shown to be translatable into LPMLN. This thesis also presents a translation of P-log into LPMLN. The translation tells how probabilistic nonmonotonicity (the ability of the reasoner to change his probabilistic model as a result of new information) of P-log can be represented in LPMLN, which yields a way to compute P-log using standard ASP solvers or MLN solvers. / Dissertation/Thesis / Masters Thesis Computer Science 2017

This thesis explores the effects of institutions on macroeconomic performance. It does so in two main chapters, a summary of each of which is given below. In the first main chapter of the thesis, the interactions between government spending, government borrowing, political corruption and political turnover were examined. Incorporating these factors in a sovereign default model, we show how sovereign default decisions and business cycle fluctuations are affected by the level of corruption. In particular, we show that when there is turnover, corruption can generate higher risks of default and higher credit spreads when there is enough stability. Intuitively, we establish that a change in power from a less corrupt to a more corrupt government is more likely to cause default than the reverse. The results also shows that households suffer welfare losses as a result of corruption. As regards business cycles, the general effect of corruption is to alter business cycle statistics. Further, we estimate an empirical model using data on sovereign default, corruption, political stability and other macroeconomic variables for a sample of emerging economies. The results of this provide strong evidence of a positive relationship between both corruption and political stability and sovereign default. The second main chapter of the thesis looks at the effects of limited financial contract enforcement in a dynamic stochastic general equilibrium framework where firms have access to both internal and external means of finance. The results shows how limited enforceability affects fluctuations in key macroeconomic variables (e.g., output, employment and price) through its impact on key financial variables (e.g., interest rates, risk premium, default risk and leverage). In particular, we find that weaker enforcement tends to amplify the effects of shocks, creating greater volatility, as well as lowering small firm funding. We provide some empirical evidence to support our results. Using cross-country data on measures of financial market imperfections, we find that limited enforcement has a negative effect on output and that this effect is exacerbated by poor credit information. We also find that weaker contract enforcement is associated with higher output volatility.

L'utilisation massive des plateformes multi-cœurs et multi-processeurs a pour effet de favoriser la programmation parallèle à mémoire partagée. Néanmoins, exploiter efficacement et de manière correcte le parallélisme sur ces plateformes reste un problème de recherche ouvert. De plus, leur modèle d'exécution sous-jacent, et notamment les modèles de mémoire "relâchés", posent de nouveaux défis pour les outils d'analyse statiques et dynamiques. Dans cette thèse nous abordons deux aspects importants dans le cadre de la programmation sur plateformes multi-cœurs et multi-processeurs: l'optimisation de sections critiques implémentées selon l'approche pessimiste, et l'analyse dynamique de flots d'informations. Les sections critiques définissent un ensemble d'accès mémoire qui doivent être exécutées de façon atomique. Leur implémentation pessimiste repose sur l'acquisition et le relâchement de mécanismes de synchronisation, tels que les verrous, en début et en fin de sections critiques. Nous présentons un algorithme générique pour l'acquisition/relâchement des mécanismes de synchronisation, et nous définissons sur cet algorithme un ensemble de politiques particulier ayant pour objectif d'augmenter le parallélisme en réduisant le temps de possession des verrous par les différentes threads. Nous montrons alors la correction de ces politiques (respect de l'atomicité et absence de blocages), et nous validons expérimentalement leur intérêt. Le deuxième point abordé est l'analyse dynamique de flot d'information pour des exécutions parallèles. Dans ce type d'analyse, l'enjeu est de définir précisément l'ordre dans lequel les accès à des mémoires partagées peuvent avoir lieu à l'exécution. La plupart des travaux existant sur ce thème se basent sur une exécution sérialisée du programme cible. Ceci permet d'obtenir une sérialisation explicite des accès mémoire mais entraîne un surcoût en temps d'exécution et ignore l'effet des modèles mémoire relâchées. A contrario, la technique que nous proposons permet de prédire l'ensemble des sérialisations possibles vis-a-vis de ce modèle mémoire à partir d'une seule exécution parallèle ("runtime prediction"). Nous avons développé cette approche dans le cadre de l'analyse de teinte, qui est largement utilisée en détection de vulnérabilités. Pour améliorer la précision de cette analyse nous prenons également en compte la sémantique des primitives de synchronisation qui réduisent le nombre de sérialisations valides. Les travaux proposé ont été implémentés dans des outils prototype qui ont permit leur évaluation sur des exemples représentatifs. / The invasion of multi-core and multi-processor platforms on all aspects of computing makes shared memory parallel programming mainstream. Yet, the fundamental problems of exploiting parallelism efficiently and correctly have not been fully addressed. Moreover, the execution model of these platforms (notably the relaxed memory models they implement) introduces new challenges to static and dynamic program analysis. In this work we address 1) the optimization of pessimistic implementations of critical sections and 2) the dynamic information flow analysis for parallel executions of multi-threaded programs. Critical sections are excerpts of code that must appear as executed atomically. Their pessimistic implementation reposes on synchronization mechanisms, such as mutexes, and consists into obtaining and releasing them at the beginning and end of the critical section respectively. We present a general algorithm for the acquisition/release of synchronization mechanisms and define on top of it several policies aiming to reduce contention by minimizing the possession time of synchronization mechanisms. We demonstrate the correctness of these policies (i.e. they preserve atomicity and guarantee deadlock freedom) and evaluate them experimentally. The second issue tackled is dynamic information flow analysis of parallel executions. Precisely tracking information flow of a parallel execution is infeasible due to non-deterministic accesses to shared memory. Most existing solutions that address this problem enforce a serial execution of the target application. This allows to obtain an explicit serialization of memory accesses but incurs both an execution-time overhead and eliminates the effects of relaxed memory models. In contrast, the technique we propose allows to predict the plausible serializations of a parallel execution with respect to the memory model. We applied this approach in the context of taint analysis , a dynamic information flow analysis widely used in vulnerability detection. To improve precision of taint analysis we further take into account the semantics of synchronization mechanisms such as mutexes, which restricts the predicted serializations accordingly. The solutions proposed have been implemented in proof of concept tools which allowed their evaluation on some hand-crafted examples.

Orientador: Germán Jesus Lozada Cruz / Banca: Alexandre Nolasco de Carvalho / Banca: Waldemar Donizete Bastos / Resumo: Neste trabalho vamos estudar um modelo matemático que descreve as oscilações não lineares de uma ponte suspensa. Este modelo é dado por um sistema de equações diferenciais parciais que estão acopladas. Basicamente, estudaremos a existência e unicidade da solução fraca do sistema. Usaremos a teoria de operadores maximais monótonos para modelo linear e os semigrupos fortemente contínuos de contração para o modelo não linear. / Abstract: In this work we study a mathematical model which describes the nonlinear oscillations of a bridge suspended. This model is given by a system of partial di®erential equations which are coupled. Basically, we study the existence and uniqueness of weak solution of the system. We use the theory of maximal monotone operators to model linear and strongly continuous semigroups of contraction for the nonlinear model. / Mestre

Despite the increasing popularity of the concept of entrepreneurship for sustainable development in both academia and policy making, there is no agreement on how this process should unfold and which objectives it should pursue. Perceived tensions between the paradigms of sustainability and economic development as well as alack of shared definitions and assumptions lead to ambiguous understandings of the idea of sustainable entrepreneurship. This thesis uses the theoretical framework of ecological economics to investigate a leading discourse within the field of sustainable entrepreneurship and aims toclarify the underlying assumptions and implications of the current discourse. The analysed discourse is created by SEED, a global UN partnership which promotes entrepreneurship for sustainable development with a focus on African countries. The discourse analysis is conducted according to four analytical elements as defined by Dryzek (1997: 2013). The theoretical reflection of the discourse through the lensof ecological economics and its strong sustainability paradigm functions as a foundation for the conceptualisation of strong sustainable entrepreneurship from which implications for the current sustainable entrepreneurship discourse are derived.

Made available in DSpace on 2014-06-11T19:22:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-01Bitstream added on 2014-06-13T19:49:16Z : No. of bitstreams: 1 valle_rml_me_sjrp.pdf: 866733 bytes, checksum: 903cda2dc88f2ecf24f8cec8bd5ce702 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho utilizamos simulações de Monte Carlo para estudar as propriedades elétricas e conformacionais de polianfóteros fracos, investigando o efeito da estrutura primária, do pH da solução da valência dos contraíons. O polímero foi representado por um conjunto de esferas rígidas conectadas por um potencial harmônico (modelo bead-spring ) e os contraíons da solução, de valência 1, 2 e 3, foram tratados de maneira explícita segundo o modelo primitivo restrito. Todo o sistema foi confinado em uma célula esférica com o polímero fixado em seu centro. Dentre as análises de propriedades elétricas do polianfótero, foi observado que a fração de grupos básicos protonados se aproxima do caso ideal com o aumento da valência dos contraíons, para todas as sequências primárias estudadas. Diferentemente do que ocorre para homopolímeros carregados, nos quais os efeitos de correlação entre contraíons multivalentes provocam alta compactação da cadeia, o raio de giração de polienfóteros com contra ons trivalentes se mostrou muito próximo de cadeias (self-avoiding walk ). Em relação ao efeito da sequência primária, cadeias com baixa carga líquida apresentaram maior compactação nos casos de distribuição de monômero com menor número de blocos, assim como já previsto na literatura utilizando eletrólito implícito através da teoria de Debye-Hückel. A medida que aumentamos o valor de pH, o polinafótero ca carregado e conformações globulares não são mais observadas. Nestas condições, verificamos a formação de estruturas conhecidas como tadpoles apenas utilizando contraíons monovalente. Em nossa análise de Scaling, os valores conhecidos na literatura para o índice v da relação Rg ~ N vm foram obtidos para os casos Alternado (caso SAW) e Dibloco (caso globular) em regimes de pH nos quais a macromolécula está neutra apenas considerando diluição infinita / In this work we use the Monte Carlo simulations to study conformational and electrical properties of weak Polyampholytes and investigate the e ect of the primary structure, pH and the valency of the counterion on these conformations. The polymer was represented by a set of rigid spheres connected by a harmonic potential (bead-spring model) and the counterions of the solution of valency 1, 2 and 3 were treated explicitly according to the restricted primitive model. The system was enclosed in a spherical cell with the polymer set at its center. Among the analysis of electrical properties of the polyampholyte, it was observed that the fraction of protonated basic groups approaches the ideal case with the increase in valency of the counterion for all the primary sequence studied. Di erently from what occurs for homopolymers, in which the e ects of correlation between multivalent counterions cause high compression of the chain, the radius of gyration of polyampholytes considering trivalent counterions is very close to those obtained for Gaussian chains with excluded volume interaction (Self-Avoiding Walk ). Regarding the e ect of primary sequence, chains with low net charge showed higher compression in cases of fewer blocks monomers distribution, as already provided in previous work using implicit counterions by the Debye-H uckel theory. As the pH increased, the polyampholyte has a net charge and globular conformations are no longer observed. Accordingly, we observed the formation of structures known as tadpoles using monovalent counterions. In our analysis of Scaling, the known values for the index (in Rg N m) were obtained for Alternating case (SAW) and Diblock case (globular) in pH regimes in which the macromolecule has no net charge and only considering in nite dilution

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In this thesis, we present the space BMO, the one-parameter Hardy-Littlewood maximal function, and the two-parameter strong maximal function. We use the John-Nirenberg inequality, the relation between Muckenhoupt weights and BMO, and the Coifman-Rochberg proposition on constructing A1 weights with the Hardy- Littlewood maximal function to show the boundedness of the Hardy-Littlewood maximal function on BMO. The analogous statement for the strong maximal function is not yet understood. We begin our exploration of this problem by discussing an equivalence between the boundedness of the strong maximal function on rectangular BMO and the fact that the strong maximal function maps A∞ weights into the A1 class. We then extend a multiparameter counterexample to the Coifman-Rochberg proposition proposed by Soria (1987) and discuss the difficulties in modifying it into an A∞ counterexample that would disapprove the boundedness of the strong maximal function.

Este trabalho propõe uma metodologia para enumerar soluções, que indiquem a barra e a compensação de potência reativa necessária para o sistema elétrico sob análise, que atendam aos requisitos avaliados pela função objetivo e as restrições. Nessa alocação de compensação ótima de potência reativa, obtemos as melhores barras e configurações de potências e tecnologias de dispositivos de compensação, minimizando as perdas totais de potência ativa da rede. Em redes fracas com conversores de frequência (por exemplo, para conexão de fontes renováveis, ou interligações utilizando conversores HVDC), esta metodologia proposta busca a melhor relação de curto-circuito trifásico (SCR) no ponto de conexão do conversor de frequência, melhorando a conexão da barra de interesse. O método busca soluções para alocar um único dispositivo de compensação, e soluções alocando simultaneamente dois dispositivos. A metodologia proposta baseia-se na enumeração exaustiva das soluções, e o estudo de caso nos sistemas de 14 e 30 barras do IEEE mostrou a aplicabilidade e funcionalidade da metodologia proposta. / This work proposes a methodology to enumerate solutions, which indicate the bar and the reactive power compensation required for the electrical system under analysis, that meet the requirements evaluated by the objective function and the constraints. In this allocation of optimal compensation of reactive power, we obtain the optimal bars and technologies of compensation devices, minimizing the total losses of active power of the network. In weak networks with frequency converters (e.g. for connection of renewable sources, or interconnections using HVDC converters), the proposed methodology seeks the best threephase short-circuit (SCR) relation at the connection point, improving the connection of the new generation. The method looks for solutions to allocate a single compensation device, and solutions to allocate two devices simultaneously. The proposed methodology is based on the exhaustive enumeration of the solutions. A case study carried out in the IEEE 14 and 30 bus systems shows the applicability and performance of the proposed methodology.

Extensões de Ore são anéis de polinômios, denotados por R[x o &], nos quais a variável x e os elementos de R não comutam necessariamente. Algebras de Hopf fracas são algebras que tamb em são coálgebras e satisfazem um conjunto de axiomas de compatibilidade entre essas estruturas. Neste trabalho investigamos extensões de Ore cujo anel base e uma algebra de Hopf fraca. Mais especi camente, dada uma algebra de Hopf fraca R, estudamos sob quais condições R[x o &] e uma algebra de Hopf fraca com uma estrutura que estende a estrutura de R. Sob certas hipóteses, obtemos condições necessárias e su cientes para que a extensão de Ore seja uma álgebra de Hopf fraca, obtendo assim um resultado que generaliza um teorema de Panov para o contexto de algebras de Hopf fracas. / Ore extensions are polynomial rings, denoted by R[x o &], in which the variable x and the elements of R do not commute necessarily. Weak Hopf algebras are algebras which are also coalgebras and satisfy a set of axioms of compatibility betweem these structures. In this work, we investigate Ore extensions whose base ring is a weak Hopf algebra. More speci cally, if R is a weak Hopf algebra then we study under what conditions R[xo &] is a weak Hopf algebra extending the structure of R. Under certain hypotheses, we obtain necessary and su cient conditions for an Ore extension to be a weak Hopf algebra, obtaining a result that generalizes a Panov's theorem to the setting of weak Hopf algebras.