Multigraph approach to quantum non-locality

Non-contextuality (NC) and Bell inequalities can be expressed as bounds $\Omega$ for positive linear combinations $S$ of probabilities of events, $S \leq \Omega$. Exclusive events in $S$ can be represented as adjacent vertices of a graph called the exclusivity graph of $S$. In the case that events correspond to the outcomes of quantum projective measurements, quantum probabilities are intimately related to the Gr\"otschel-Lov\'asz-Schrijver theta body of the exclusivity graph. Then, one can easily compute an upper bound to the maximum quantum violation of any NC or Bell inequality by optimizing $S$ over the theta body and calculating the Lov\'asz number of the corresponding exclusivity graph. In some cases, this upper bound is tight and gives the exact maximum quantum violation. However, in general, this is not the case. The reason is that the exclusivity graph does not distinguish among the different ways exclusivity can occur in Bell-inequality (and similar) scenarios. An interesting question is whether there is a graph-theoretical concept which accounts for this problem. Here we show that, for any given $N$-partite Bell inequality, an edge-coloured multigraph composed of $N$ single-colour graphs can be used to encode the relationships of exclusivity between each party's parts of the events. Then, the maximum quantum violation of the Bell inequality is exactly given by a refinement of the Lov\'asz number that applies to these edge-coloured multigraphs. We show how to calculate upper bounds for this number using a hierarchy of semi-definite programs and calculate upper bounds for $I_3$, $I_{3322}$ and the three bipartite Bell inequalities whose exclusivity graph is a pentagon. The multigraph-theoretical approach introduced here may remove some obstacles in the program of explaining quantum correlations from first principles.Comment: 21 pages, 5 figure

A stochastic precipitation generator conditioned by a climate index.

This work presents a stochastic daily precipitation generator that incorporates a climate index to reflect the associated, seasonally varying, influence on simulated precipitation statistics. The weather generator is based on a first-order, two-state Markov chain to simulate the occurrence of daily precipitation and a gamma distribution to compute the nonzero daily precipitation amounts. Therefore, it has four parameters that are, in turn, allowed to vary daily following an autoregressive linear model in Gaussian space that simulates the parameters’ deviations from their climatological seasonal cycle. This model is forced by the independently predicted evolution of a climate index and captures how the model parameters and, therefore, precipitation are gradually shifted by the associated climate signal. In this case, the Niño-3.4 index is used to account for the influence of the El Niño–Southern Oscillation (ENSO) phenomenon on precipitation in Uruguay. However, the methodology is general and could be readily transferable to indices of other climate modes or downscaling algorithms for seasonal climate prediction. The results show that the proposed methodology successfully captures the ENSO signal on precipitation, including its seasonality. In doing so, it greatly reduces the underestimation of the seasonal and interannual precipitation variability, a well-known limitation of standard weather generators termed the “overdispersion” phenomenon. This work opens interesting opportunities for the application of seasonal climate forecasts in several process-based models (e.g., crop, hydrological, electric power system, water resources), which may be used to inform the decision-making and planning processes to manage climate-related risks

Economic impact of considering El Niño-Southern Oscillation on the representation of streamflow in an electric system simulator

The Electric Power System Simulator (SimSEE) is a model that optimizes and simulates the operation of an electric system and has been widely used to analyze the integrated power system in Uruguay. Among the stochastic processes that SimSEE needs to represent are the streamflow inputs to the hydroelectric dams, which constitute a key factor for both energy dispatches and mid-term planning. A dominant feature of streamflow time series is that they show very high interannual variability, which represents a major uncertainty for energy operation in Uruguay. Part of this variability is associated with El Niño-Southern Oscillation (ENSO) phenomena. In this work, a climate index associated with ENSO is incorporated to the stochastic generator of streamflow series used by the SimSEE. Forty six-month-long simulations are performed with and without such modifications. We find that the system operator can take advantage of the ENSO-related information incorporated to SinSEE in 65% of the cases (semesters) considered, reducing the total costs of operation. This result still holds in a scenario with larger firm capacity. The amounts saved, however, are reduced as the firm capacity increases. The enhanced generation options associated with a larger firm capacity diminish the overall costs of generation, especially in times of low streamflow, rendering the savings associated with a more efficient management of the reservoir less significant. Keywords : economic impact, electric system simulator, ENSO, stochastic process, streamflow representatio

BIOGRAFAR, IMAGINAR, ESCREVER: ESCRITA BIOGRÁFICA E IMAGINAÇÃO HISTÓRICA EM JOÃO MANUEL PEREIRA DA SILVA (1817-1898)

This  article  seeks  to  study  the  relationship  between  biographical  writing  and historical  imagination  in  the  works  of  João  Manuel  Pereirada  Silva,  especially  in  Plutarco Brasileiro. The twenty biographies produced by the historian in this work constitute the main source of this work. From these, it is possible to understand the author's thinking about the use of the imaginative capacity inthe historiographic work. Later on, from the reflections of Luiz Costa Lima, it will be shown how Pereira da Silva exerts on his historical novels a control of the imaginary in order to guide his readers for a possible reading of his work.Este artigo busca estudar a relação entre escrita biográfica e imaginação histórica nas obras de João Manuel Pereira da Silva, especialmente em Plutarco Brasileiro. As vinte biografias produzidas pelo historiador nesse trabalho constituem a fonte principal deste trabalho. A partir delas, é possível compreender o pensamento do autor sobre a utilização da capacidade imaginativa no trabalho historiográfico. Posteriormente, a partir das reflexões de Luiz Costa Lima, será demonstrado de que forma Pereira da Silva exerce sobre seus romances históricos um controle do imaginário a fim de orientar seus leitores para uma leitura possível de sua obra

Biografia e Historia Magistra Vitae : aproximações e afastamentos no Brasil oitocentista

Pereira da Silva (1817-1898) foi um dos historiadores mais profícuos do século XIX. No ano de 1847, ele publica Plutarco Brasileiro. Nessa obra, encontram-se vinte biografias de importantes personalidades que, na sua imensa maioria, viveram durante o período colonial, sobretudo de escritores e poetas. Uma leitura mais detalhada da obra em questão permite depreender que a relação estabelecida com o tempo ali é, em um primeiro momento, caracterizada pela ideia de continuidade entre passado, presente e futuro, em que o passado parece ser o princípio norteador entre os três estratos temporais. Nesse sentido, a biografia, ou em melhores termos, a escrita biográfica torna-se útil na medida em que possibilita o cumprimento de um dever para com os tempos pretéritos. Ou seja, há implícito em Plutarco Brasileiro um sentido moralizante, encomiástico e memorialístico. Com isso, a opção pela biografia, enquanto gênero de escrita, aproximava-se da historia magistra vitae na tentativa de legar à posteridade os feitos dos homens do passado para serem passíveis de imitação no presente. Por sua vez, Um estadista do Império, de Joaquim Nabuco (1849-1910), é publicado no ano de 1898. A obra conta a vida de José Tomás Nabuco de Araújo Filho. Contudo, para além de somente retratar a vida de seu pai, Nabuco também busca traçar um quadro de época, no caso o Segundo Reinado. Ao buscar isso, a obra ultrapassou os limites encontrados pela biografia de dever memorialístico. Esta tese buscar compreender de que modo biografia e história se relacionaram no Brasil do século XIX, tendo como eixo central de análise os trabalhos dos referidos autores. Objetiva-se, por conseguinte, demonstrar que as aproximações entre biografia e história não se estabeleceram por uma única diretriz. A hipótese é que essa mudança, que não se dá de maneira linear e nem progressiva, está associada à própria disciplina histórica, pensada como singular coletivo. Na medida em que a história busca sua autonomia disciplinar e passa por reconfigurações relacionadas ao tempo histórico, a produção de biografias parece indicar uma importante mudança em sua concepção.Pereira da Silva (1817-1898) was one of the most fruitful historians of the 19th century. In the year 1847, he published Plutarco Brasileiro. In this work, there are twenty biographies of important personalities who, in the vast majority, lived during the colonial period, especially of writers and poets. A more detailed reading of the work in question allows us to understand that the relationship established with time there is, at first, characterized by the idea of continuity between past, present and future, in which the past seems to be the guiding principle between the three strata temporal. In this sense, biography, or in better terms, biographical writing becomes useful to the extent that it makes it possible to fulfill a duty towards past times. In other words, there is implicit in Plutarco Brasileiro a moralizing, commendable and memorialistic sense. With this, the option for biography, as a genre of writing, approached the history magistra vitae in an attempt to bequeath to posterity the deeds of men of the past to be subject to imitation in the present. In turn, A statesman of the Empire, by Joaquim Nabuco (1849-1910), is published in the year 1898. The work tells the life of José Tomás Nabuco de Araújo Filho. However, in addition to only portraying his father's life, Nabuco also seeks to draw a picture of the period, in this case the Second Reign. In seeking this, the work went beyond the limits found by the biography of memorialistic duty. This thesis seeks to understand how biography and history were related in 19th century Brazil, having as a central axis of analysis the works of these authors. Therefore, the objective is to demonstrate that the approximations between biography and history were not established by a single guideline. The hypothesis is that this change, which is neither linear nor progressive, is associated with the historical discipline itself, thought of as a collective singular. As history seeks its disciplinary autonomy and undergoes reconfigurations related to historical time, the production of biographies seems to indicate an important change in its conception

História e justiça: sobre os usos políticos do passado

This brief essay aims to understand how the relationship between History and Justice, the historian and the judge, arises from debates, sometimes controversial, that occurred around the Holocaust. Using as a reference the discussions that took place in France and Germany, this essay is based mainly on the judicial process involving the writer David Irving and the historian Deborah Lipstadt. In the final part of this work, the films Denial (2016) and Judgment at Nuremberg (1961), are referred to as examples of cinema's ability to demonstrate how history is mobilized in the courts.Este breve ensaio tem o objetivo de compreender de que modo ocorre a relação entre História e Justiça, o historiador e o juiz, a partir de debates, por vezes polêmicos, ocorridos em torno do Holocausto. Utilizando como referência as discussões acontecidas na França e na Alemanha, este ensaio baseia-se principalmente no processo judicial envolvendo o escritor David Irving e a historiadora Deborah Lipstadt. Na parte final deste trabalho, os filmes Negação (2016) e Tribunal de Nuremberg (1961) são referenciados como exemplos da capacidade do cinema de demonstrar como a história é mobilizada nos tribunais. &nbsp

EM DEFESA (DE QUAL) DA HISTÓRIA? REFLEXÕES SOBRE PÓSMODERNIDADE E MARXISMO A PARTIR DA ESCRITA DA HISTÓRIA.

This article basically consists of a bibliographical discussion and review made and motivated during the last class of the discipline of Social Relations of Domination and Resistance - Bibliographic Analysis 1, at the Federal University of Rio Grande do Sul. The problematic, at that moment, concerned the different ways of conceiving historical knowledge. In this sense, I favored a reflection on the writing of history, from the modernity / post-modernity debate. If the beginning of this article starts from the reading of the collection organized by Ellen Wood and John Foster, throughout the text, other authors were necessary for the reflection to deepen. Keywords: History of historiography; Historical knowledge; Story writing.Este artigo consiste basicamente em uma discussão e revisão bibliográficas feitas e motivadas durante a última aula da disciplina de Relações Sociais de Dominação e Resistência - Análise Bibliográfica 1, na Universidade Federal do Rio Grande do Sul. A problemática, naquele momento, dizia respeito sobre as diferentes formas de se conceber o conhecimento histórico. Nesse sentido, privilegiei uma reflexão sobre a escrita da história, a partir do debate modernidade/pós-modernidade. Se o início deste artigo parte da leitura realizada da coletânea organizada por Ellen Wood e John Foster, ao longo do texto outros autores foram necessários para que a reflexão se aprofundasse. RECEBIDO: 09.02.2018 AVALIADO: 05.04.201