Sistemas de lógica modal em dedução natural

Formalization of logical systems in natural deduction brings many metatheoretical advantages, which Normalization proof is always highlighted. Modal logic systems, until very recently, were not routinely formalized in natural deduction, though some formulations and Normalization proofs are known. This work is a presentation of some important known systems of modal logic in natural deduction, and some Normalization procedures for them, but it is also and mainly a presentation of a hierarchy of modal logic systems in natural deduction, from K until S5, together with an outline of a Normalization proof for the system K, which is a model for Normalization in other systems

Of madness and many-valuedness: an investigation into Suszko's Thesis

Suszko’s Thesis is a philosophical claim regarding the nature of many-valuedness. It was formulated by the Polish logician Roman Suszko during the middle 70s and states the existence of “only but two truth values”. The thesis is a reaction against the notion of many-valuedness conceived by Jan Łukasiewicz. Reputed as one of the modern founders of many-valued logics, Łukasiewicz considered a third undetermined value in addition to the traditional Fregean values of Truth and Falsehood. For Łukasiewicz, his third value could be seen as a step beyond the Aristotelian dichotomy of Being and non-Being. According to Suszko, Łukasiewicz’s ideas rested on a confusion between algebraic values (what sentences describe/denote) and logical values (truth and falsity). Thus, Łukasiewicz’s third undetermined value is no more than an algebraic value, a possible denotation for a sentence, but not a genuine logical value. Suszko’s Thesis is endorsed by a formal result baptized as Suszko’s Reduction, a theorem that states every Tarskian logic may be characterized by a two-valued semantics. The present study is intended as a thorough investigation of Suszko’s thesis and its implications. The first part is devoted to the historical roots of many-valuedness and introduce Suszko’s main motivations in formulating the double character of truth-values by drawing the distinction in between algebraic and logical values. The second part explores Suszko’s Reduction and presents the developments achieved from it; the properties of two-valued semantics in comparison to many-valued semantics are also explored and discussed. Last but not least, the third part investigates the notion of logical values in the context of non-Tarskian notions of entailment; the meaning of Suszko’s thesis within such frameworks is also discussed. Moreover, the philosophical foundations for non-Tarskian notions of entailment are explored in the light of recent debates concerning logical pluralism.

Estudo teórico das propriedades eletrônicas e termodinâmicas de nanofitas quasiperiódicas BCN

Nanoscale materials composed of boron, nitrogen, and carbon have unique properties and may be useful in new technologies. In this thesis, we investigate some properties of BCN nanoribbons constructed according to the Fibonacci quasiperiodic sequence. We analyze properties such as structural stability, electronic density of states, electronic specific heat, band structure, and energy band gap. We have performed first-principles calculations based on density functional theory implemented in the SIESTA code. The results showed that nanoribbons present a fixed value of the formation energy. The electronic density of states was used to calculate the specific heat. We found an oscillatory behavior of the electronic specific heat, in the low temperature regime. We analyze the electronic band structure to determine the energy band gap. The energy band gap oscillates as a function of the Fibonacci generation index n. Our work suggest that appropriate choice of the building block materials of the quasiperiodic sequence, may lead to a tuneable band gap of the quasiperiodic nanoribbons.

Todo nordeste que couber a gente publica: o The New York Times e as representações do nordeste brasileiro na era da política da boa vizinhança (1933-1945)

The Brazilian Northeast has been a constant subject for journalists of one of the world's leading media companies - The New York Times - between 1933 and 1945. This time, the US government implemented a new foreign policy for Latin America - known as the Good Neighbor Policy. It preached, various points including more respect and attention to the countries south of U.S. borders. Because of her geostrategic importance, Brazil was one of the countries that received the most attention of the bureaucracy and American press. This study investigates the multiple Northeast representations formulated in The New York Times' pages when the Americans were spotlight is on the region. It delineates similarities and differences between the NYT, the press and the governments of the United States and Brazil from the ways of conceiving this particular part of Brazil. Through the analysis of texts, photographs and maps, it is dedicated to establish connections between spaces, press and politics of the 1930s and 1940s. These decades there were relevant changes in the political landscape of both countries that permeated the news, reports and articles of NYT. Circumstances such as the 1935 armed uprisings - known as Communist Conspiracy - the installation and operation of the New State, and especially the Brazilian and US participation in World War II and the bilateral negotiations on the installation of US bases in Brazil were cardinal for the various Northeast images that circulated in the publication. The region was repeatedly subject of correspondent of the New York newspaper in Brazil, Frank M. Garcia, but also present on matters of professionals responsible for various sections: review of books, publishing, tourism, foreign affairs, etc. Along the investigated period, the visions of the region made in the articles published in the newspaper that suffered major metamorphoses. Starting with Northeast of the drought, famine and death recurrent in Brazilian literature to the most dangerous point for hemispheric defense, passing through representations of the American West lawless nineteenth century and the Latin America marked by the dominance of exotic nature and stagnation, a space to be transformed by the US technical knowledge.

Grande Missa Nordestina de Clóvis Pereira: estudo para interpretação

Esse trabalho tem como objetivo realizar um estudo sobre os elementos técnicos, estéticos e históricos, que possa contribuir para uma interpretação mais consciente e consistente da GRANDE MISSA NORDESTINA, do compositor Clóvis Pereira. Escrita para coro, solistas e orquestra em 1977, essa obra se destaca por ser uma das principais composições produzidas em Pernambuco durante o Movimento Armorial nos anos de 1970. Pretendemos na primeira parte, expor como uma cadeia consequente de elos a partir da experiência de vida do compositor, aliada à sua vivência musical, assim como, ao conhecimento técnico e estético junto a nomes como César Guerra-Peixe e Ariano Suassuna, geraram uma práxis musical, tornando essa obra uma espécie de síntese da produção do compositor nesse período. Na segunda parte apresentaremos um conjunto de sugestões interpretativas a partir das ideias musicais extraídas entre a comparação das duas gravações realizadas pelo compositor, assim como, do relato de experiências adquiridas pelo autor desse trabalho durante os processos de interpretação dessa obra.