Semantics of logic programs with explicit negation

After a historical introduction, the bulk of the thesis concerns the study of a declarative semantics for logic programs. The main original contributions are: ² WFSX (Well–Founded Semantics with eXplicit negation), a new semantics for logic programs with explicit negation (i.e. extended logic programs), which compares favourably in its properties with other extant semantics. ² A generic characterization schema that facilitates comparisons among a diversity of semantics of extended logic programs, including WFSX. ² An autoepistemic and a default logic corresponding to WFSX, which solve existing problems of the classical approaches to autoepistemic and default logics, and clarify the meaning of explicit negation in logic programs. ² A framework for defining a spectrum of semantics of extended logic programs based on the abduction of negative hypotheses. This framework allows for the characterization of different levels of scepticism/credulity, consensuality, and argumentation. One of the semantics of abduction coincides with WFSX. ² O–semantics, a semantics that uniquely adds more CWA hypotheses to WFSX. The techniques used for doing so are applicable as well to the well–founded semantics of normal logic programs. ² By introducing explicit negation into logic programs contradiction may appear. I present two approaches for dealing with contradiction, and show their equivalence. One of the approaches consists in avoiding contradiction, and is based on restrictions in the adoption of abductive hypotheses. The other approach consists in removing contradiction, and is based in a transformation of contradictory programs into noncontradictory ones, guided by the reasons for contradiction.

Transverse Vibrations in Beams Supported by a Piece-Wise Homogeneous Visco- Elastic Foundation

Transversal vibrations induced by a load moving uniformly along an infinite beam resting on a piece-wise homogeneous visco-elastic foundation are studied. Special attention is paid to the additional vibrations, conventionally referred to as transition radiations, which arise as the point load traverses the place of foundation discontinuity. The governing equations of the problem are solved by the normalmode analysis. The solution is expressed in a form of infinite sum of orthogonal natural modes multiplied by the generalized coordinate of displacement. The natural frequencies are obtained numerically exploiting the concept of the global dynamic stiffness matrix. This ensures that the frequencies obtained are exact. The methodology has restrictions neither on velocity nor on damping. The approach looks simple, though, the numerical expression of the results is not straightforward. A general procedure for numerical implementation is presented and verified. To illustrate the utility of the methodology parametric optimization is presented and influence of the load mass is studied. The results obtained have direct application in analysis of railway track vibrations induced by high-speed trains when passing regions with significantly different foundation stiffness.

As 'conversas informais' extraprocessuais como meio de prova em processo penal

In the present thesis, we examine the approach to the so-called “informal conversations”, especially between a suspect or defendant and criminal police authorities. Our goal is to understand if criminal police authorities are allowed to testify about the content of these conversations, revealing facts that the suspect or defendant may have shared with them, as well as about evidence that they may have acquired through these statements. Firstly, we briefly present the notion of “informal conversations” and the great variety of situations they may encompass: intra or extra-procedural; prior or subsequent to someone acquires the status of defendant. Secondly, we analyse some of the principles and rules that are involved in this controversial issue: principles concerning the procedural structure, organization and dynamic; principles concerning the production and assessment of evidence in the trial hearing; principles concerning the prosecution and the powers of criminal police authorities; the procedural status of the defendant; the rules concerning the reading of statements in the trial hearing; the rules concerning hearsay testimonies. Thirdly, we go through the great amount of case law on the so-called “informal conversations” and related matters, analysing the most relevant cases and the arguments that sustain them, as well as the legal literature. Our goal is to understand the evolution, throughout the last two decades, of the different opinions regarding the approach to the various situations in which “informal conversations” may occur and in which the admissibility of a testimony by criminal police authorities is questioned. Finally, we defend a different approach for testimonies by criminal police authorities prior and subsequent to someone acquiring the status of defendant. We see the moment when someone acquires the status of defendant as a border area in the admissibility of “informal conversations”, because from then on the statements have to be collected and assessed according to the law, so all the other conversations (or any other evidence) collected informally are irrelevant. As to the specific case of the testimony about the re-enactment of the crime, given the high degree of difficulty in separating the defendant’s contributions that may be considered essential and those that may be considered less useful, but still relevant, we support the qualification of the defendant’s contributions as inseparable from the re-enactment, allowing it to be replicated and assessed in the trial hearing with no restrictions.

Market risk charge of the trading book: a comparison of the Basel II and Basel III

This paper aims to investigate if the market capital charge of the trading book increased in Basel III compared to Basel II. I showed that the capital charge rises by 232% and 182% under the standardized and internal model, respectively. The varying liquidity horizons, the calibration to a stress period, the introduction of credit spread risk, the restrictions on correlations across risk categories and the incremental default charge boost Basel III requirements. Nevertheless, the impact of Expected shortfall at 97.5% is low and long term shocks decrease the charge. The standardized approach presents advantages and disadvantages relative to internal models.

Is the Basel III Leverage Ratio countercyclical? A study for Portuguese banks

This work analyses how the leverage ratio behaves through the cycle, vis-à-vis other capital ratios. For a sample of the largest Portuguese banks, the Basel III leverage ratio is indeed countercyclical. This result is relevant from a regulatory perspective, since the introduction of a limit on the leverage ratio will function as a restriction in the banks’ balance sheet size, reducing the economic costs associated with the excessive growth of leverage in periods of economic expansion followed by aggressive deleveraging in the downturn. However, one cannot exclude that restrictions on banks’ leverage incentivize its transference to less regulated intermediaries.

Portuguese commercial banking: An assessment of competition in the 1960-2013 period

Strong consolidation is one of the most evident developments of banking markets around the world in recent decades. This change is raising questions on how and to what an extent competition is affected by the expansion of the largest banks. The aim of the present study is to measure the degree of competition in the Portuguese commercial banking market in the long-run, during the period ranging from1960 to 2013, by using the non-structural model developed by Panzar and Rosse. The main findings are that the Portuguese banking system, despite the legal restrictions in place, operated mostly in a market with some degree of competition and, at some points in time, presented some interesting competitive features. More recently, it has evolved into functioning as a cartel.

A cultura da vinha em Portugal e as consequências da adesão à União Europeia. Caso de estudo: A Região Demarcada do Douro

O negócio do vinho em Portugal esteve sempre sujeito a crises que resultaram da lei da oferta e da procura, ou seja, da produção e do consumo. Considerado um bom caso de integração na União Europeia (UE), levou-nos a questionar a sua dinâmica, com o foco na componente da vinha, após a adesão à então Comunidade Económica Europeia e compreender as transformações entretanto ocorridas. Desde o século XVIII, o vinho tem uma forte presença na historiografia e na cultura portuguesa. Portugal é pioneiro a nível internacional na demarcação de uma região vitícola, a região do Douro, e no papel que o Estado desempenhou. Se há atividade económica que se impôs em Portugal como lobby foi o vinho, com evidência para a época entre o final do século XIX e meados do século XX. Com este objetivo fez-se uma resenha histórica da vinha em Portugal. O condicionamento da cultura da vinha com início em 1932, por um lado, e as regiões vitícolas por outro, (que, embora criadas no início do século passado, possuem as suas raízes em épocas anteriores), sofreram o impacto da adaptação à União Europeia e à sua organização comum do mercado para a vinha e o vinho. O país teve de se harmonizar com novas regras, construir um cadastro vitícola atualizado e uniformizar as suas instituições ao edifício legal da UE. A aplicação das políticas estruturais e de coesão foram um pilar fundamental para a renovação dos vinhedos envelhecidos, incentivando a modernização de práticas culturais e dinamizando novas regiões. A opção por este território é o corolário de um estudo de caso da região mais internacional e mais sujeita a regras de restrição, que procurou manter a sua gestão secular e abrir-se à modernização. O despertar de uma região adormecida levou ao aparecimento de algumas práticas mais agressivas ou erradas, mas nunca colocou em perigo a sua substância e o seu capital mais precioso, o vinho do Porto. Em suma, é apropriado afirmar, face ao resultado da investigação desenvolvida, que Portugal teve ganhos importantes na renovação do património vitícola e na redescoberta das suas castas tradicionais, ao mesmo tempo que deu uma nova vida a toda a cadeia que produz o vinho. As novas necessidades encontradas conduziram a uma estratégia de incentivo à internacionalização da fileira assentando na promoção, na expansão dos vinhos em países específicos e na divulgação internacional do património genético das variedades tradicionais. O aumento do valor das exportações, contribuindo para uma melhoria da balança comercial, espelha a boa rentabilidade dos investimentos realizados e é um suporte para levar a cabo uma estratégia coletiva que atenue as crises cíclicas e reforce a marca “Wines of Portugal” como abóbada para a internacionalização das marcas portuguesas.

As Necrópoles alto-medievais do concelho de Cascais : séculos VI e VII

A presente dissertação teve como finalidade estudar os testemunhos arqueológicos respeitantes às práticas funerárias levadas a cabo no atual concelho de Cascais durante os séculos VI e VII. As necrópoles em estudo são sítios bem conhecidos pelos investigadores, uma vez que a descoberta de algumas é precoce, datando de finais do século XIX. Com este trabalho, pretendeu-se introduzir uma série de componentes que a investigação privilegia atualmente, sobretudo no que respeita às vivências nos espaços rurais entre o fim do Império Romano e o domínio muçulmano na Península Ibérica. A investigação desenvolvida baseou-se no estudo preliminar das coleções osteológicas de quatro das cinco necrópoles, bem como na prospeção e no levantamento arqueológicos. O inventário antropológico teve como objetivo apurar o número mínimo de indivíduos por necrópole e por sepultura e fazer uma caracterização básica do sexo e da idade dos inumados. A prospeção assentou na análise das fontes bibliográficas sobre os sítios. Os trabalhos de campo desenvolveram-se no sentido de apurar o estado de conservação dos vestígios, na eventual identificação de outros novos e no consequente levantamento gráfico e fotográfico dos mesmos. Foi igualmente examinado o espólio cerâmico e metálico recolhido aquando da escavação das necrópoles, de modo obter uma visão abrangente sobre os rituais funerários e a estabelecer cronologias mais precisas. Embora se trate de um estudo limitado devido à inexistência de um registo mais rigoroso dos vestígios, foi possível tirar algumas conclusões e constatar alguns padrões. Os resultados possibilitaram apontar um conjunto de condições que se repetem nos locais onde estes cemitérios se implantam, percebendo dinâmicas em relação a fatores de caráter natural e de carácter antrópico. Também se apurou que existiriam diferentes formas de organizar os espaços funerários e que estes seriam constituídos por sepulturas muito diversas do ponto de vista construtivo. Além disso, começa-se a desvelar as razões para a reutilização de sepulturas para vários enterramentos e a entender a forma como as comunidades rurais conduziam os rituais funerários, ainda muito enraizados numa antiga matriz pagã.

Crowdfunding

Crowdfunding, as we know it today, is a very recent activity that was born almost accidentally in the end of the 90’s decade. Due to the advent of the internet and the social networks, entrepreneurs are now able to promote their projects to a very large community. Whether it is composed by family, friends, acquaintances or simply people that are interested in the same topic or share the passion, the community is able to fund new ventures by individually investing modest amounts of money. In return, the entrepreneur can offer symbolic rewards, shares or other financial returns. New crowdfunding platforms are born almost every day all over the world, offering a new way of raising capital for their projects or a new way to invest their money in innovative ventures. Although crowdfunding is still finding its place in the financial services, successful cases such as Kickstarter demonstrate the power of the crowd in boosting creativity and productivity, financing thousands of projects by raising millions of dollars from thousands of investors. Due to regulatory restrictions, the most prominent model for now is reward-based crowdfunding, where the investors are prized with symbolic returns or privileged access to the products or services offered by the entrepreneurs. Other models such as peer-to-peer lending are also surging, allowing borrowers access to capital at a lower cost compared to so-called traditional financial institutions, and offering lenders a higher rate of return. But when it comes to offering shares to investors, i.e. using equity-based crowdfunding, entrepreneurs face regulatory obstacles in almost every country, where legislation was passed decades ago with the objective of promoting financially-capable ventures and protecting investors. Access to capital has become more difficult after the global economic recession of 2008, and for most countries it will not get easier in the near future, leaving start-ups and small enterprises with few options to start or expand their operations. In this study we attempt to answer the following research questions: how has equity-based crowdfunding evolved since its creation? Where and how has equity-based crowdfunding been implemented so far? What are the constraints and opportunities for implementing equity-crowdfunding in the world, and more particularly in Portugal? Finally, we will discuss the risks of crowdfunding and reflect on the future of this industry.