5,788 research outputs found

    Symbolic Abstractions for Quantum Protocol Verification

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    Quantum protocols such as the BB84 Quantum Key Distribution protocol exchange qubits to achieve information-theoretic security guarantees. Many variants thereof were proposed, some of them being already deployed. Existing security proofs in that field are mostly tedious, error-prone pen-and-paper proofs of the core protocol only that rarely account for other crucial components such as authentication. This calls for formal and automated verification techniques that exhaustively explore all possible intruder behaviors and that scale well. The symbolic approach offers rigorous, mathematical frameworks and automated tools to analyze security protocols. Based on well-designed abstractions, it has allowed for large-scale formal analyses of real-life protocols such as TLS 1.3 and mobile telephony protocols. Hence a natural question is: Can we use this successful line of work to analyze quantum protocols? This paper proposes a first positive answer and motivates further research on this unexplored path

    A Prize to Give for: An Experiment on Public Good Funding Mechanisms

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    This paper investigates fund-raising mechanisms based on a prize as a way to overcome free riding in the private provision of public goods, under the assumptions of income heterogeneity and incomplete information about income levels. We compare experimentally the performance of a lottery, an all-pay auction and a benchmark voluntary contribution mechanism. We find that prize-based mechanisms perform better than voluntary contribution in terms of public good provision after accounting for the cost of the prize. Comparing the prize-based mechanisms, total contributions are significantly higher in the lottery than in the all-pay auction. Focusing on individual income types, the lottery outperforms voluntary contributions and the all-pay auction throughout the income distribution.Auctions, Lotteries, Public Goods, Laboratory Experiments

    The square as the epicenter of local development

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    There is no denying that the capital has penetrated too deep and far away in body and soul of the people, in their intelligence, psyche and imagination, in their core of 'vitality'; and while such 'vitality' has become the primary source of value in capitalism. In addition to this, the dramatic centralization of political and economic power that characterizes our way of organizing society leads, ultimately, a deep divorce between the citizen’s requirements and the content of economic and social development. The local empowerment emerges as a new way to aggregate, create meaning, invent devices for appreciation and self-respect; and also an important tool that can facilitate the organized expression of community needs and assist in setting democratic priorities of local development. There is no doubt that something new is emerging in various parts of the territory in Sao Paulo – the biggest city of Brazil, with over eleven billion people. It is remarkable that there is a growing desire and political will of the inhabitants to relinquish their passive attitudes and assume, collectively, the changes in favor of the creation of improved living conditions of the neighborhood. In an area comprising four neighborhoods of the west Sao Paulo it was identified three social experiences that follows singular paths, but have the same goal: promoting the improvement of the square nearby their homes and, thereby, encourage the use of public space. The aim of this report is to analyze these three social experiences and compare them with the concept of local development. To support this essay, it was made a literature review on the concept of Development and Local Development based, fundamentally, on the ideas of Amartya Sen, Ladislau Dowbor, Ignacy Sachs, Celso Furtado and Alain Lipietz. The author of this essay participated actively in the three social experiments from February to December 2010 producing 'thick descriptions' (GEERTZ, 1989) about the meetings, the dynamics of neighborhoods and squares and informal conversations with participants. This essay concludes that the square in the urban territory can symbolize the epicenter of local development. Key words: social experiences; square; local empowerment; local development.

    A numerical method for the dynamics of non-spherical cavitation bubbles

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    A boundary integral numerical method for the dynamics of nonspherical cavitation bubbles in inviscid incompressible liquids is described. Only surface values of the velocity potential and its first derivatives are involved. The problem of solving the Laplace equation in the entire domain occupied by the liquid is thus avoided. The collapse of a bubble in the vicinity of a solid wall and the collapse of three bubbles with collinear centers are considered

    Suarez resurgitur : adapting the early modern Jus Gentium in contemporary international jurisprudence : on the fourth centenary of' Francisco Suarez's De legibus

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    Taking its cues from Francisco Suarez's treatise De legibus (1612) and from a recent case before the International Court of Justice, this article examines the parallels between the Spanish philosopher's view of the 'jus gentium', as a law concerning both the relations between states and humanity as a whole, and contemporary trends in international jurisprudence, which reject the exclusively inter-state conception of international law that shaped its underlying philosophy and 'practice for over three centuries after the Treaty of Westphalia (1648). In the context of the gradual recognition of individuals as true subjects of international law, resulting from the rise of humanitarian and human rights law and accelerated by globalisation, Suarez's vision of a strong complementary connection between individuals and states as holders of rights and bearers of obligations may offer some useful insights and perspectives for the philosophical underpinning of future developments in international law.peer-reviewe

    A Reduced Semantics for Deciding Trace Equivalence

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    Many privacy-type properties of security protocols can be modelled using trace equivalence properties in suitable process algebras. It has been shown that such properties can be decided for interesting classes of finite processes (i.e., without replication) by means of symbolic execution and constraint solving. However, this does not suffice to obtain practical tools. Current prototypes suffer from a classical combinatorial explosion problem caused by the exploration of many interleavings in the behaviour of processes. M\"odersheim et al. have tackled this problem for reachability properties using partial order reduction techniques. We revisit their work, generalize it and adapt it for equivalence checking. We obtain an optimisation in the form of a reduced symbolic semantics that eliminates redundant interleavings on the fly. The obtained partial order reduction technique has been integrated in a tool called APTE. We conducted complete benchmarks showing dramatic improvements.Comment: Accepted for publication in LMC

    Partial Order Reduction for Security Protocols

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    Security protocols are concurrent processes that communicate using cryptography with the aim of achieving various security properties. Recent work on their formal verification has brought procedures and tools for deciding trace equivalence properties (e.g., anonymity, unlinkability, vote secrecy) for a bounded number of sessions. However, these procedures are based on a naive symbolic exploration of all traces of the considered processes which, unsurprisingly, greatly limits the scalability and practical impact of the verification tools. In this paper, we overcome this difficulty by developing partial order reduction techniques for the verification of security protocols. We provide reduced transition systems that optimally eliminate redundant traces, and which are adequate for model-checking trace equivalence properties of protocols by means of symbolic execution. We have implemented our reductions in the tool Apte, and demonstrated that it achieves the expected speedup on various protocols

    Interdisciplinary teams training strategies and methodology to work in habitat

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    La interdisciplina es una construcción a la que no se accede espontáneamente ya que, en sí, conlleva una ruptura epistemológica con la forma de adquirir los conocimientos unidisciplinarios, e introduce una dimensión vital, grupal y no solo profesionalmente referencial al involucrarse en la acción. Formar la capacidad interdisciplinaria en la universidad es una opción que desarrollamos aquí. Se plantean algunas características de la formación inicial de equipos, encuadrada en la teoría de los grupos operativos, asistidos por una coordinación que facilita el proceso hacia la interdisciplina. Proceso que requiere de una lectura y elaboración de las líneas de poder que se juegan en el interior de esos grupos y en las formas de transferencia hacia la intervención en las comunidades. Al llevar la propuesta al territorio, definimos hábitat y metodologías para el encuentro con pobladores. Encuentro que coloca a esos pobladores en el lugar de decisión de las características que desean para el territorio habitado por ellos. Tanto la formación en gabinete como la práctica en terreno son instancias de aprendizaje fundamental para actuar en el hábitat.Interdisciplinary group work is not a spontaneous construction because it has an epistemological rupture with the way the uni-disciplinary knowledge is acquired, introducing common vital dimensional and nonreferential action. To teach interdisciplinary capacities is a procedure we developed at university. We build these capacities by introducing some characteristics for the formation of the initial groups; this fits within the theory of the operatives groups. This kind of groups needs specific roles of coordination and facilitation, in order to go through the process toward interdisciplinary. In a second instance, when the interdisciplinary team take this proposal to the territory, we define the habitat and methodology to meet the inhabitants. The encounter professionals and inhabitants empower the action in a decision making position about the characteristics they would like to have for their own territory. These methodologies and practice made the team and inhabitant assume the fundamental learning to take charge of their own territory and habitat

    The square as the epicenter of local development

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    There is no denying that the capital has penetrated too deep and far away in body and soul of the people, in their intelligence, psyche and imagination, in their core of 'vitality'; and while such 'vitality' has become the primary source of value in capitalism. In addition to this, the dramatic centralization of political and economic power that characterizes our way of organizing society leads, ultimately, a deep divorce between the citizen's requirements and the content of economic and social development. The local empowerment emerges as a new way to aggregate, create meaning, invent devices for appreciation and self-respect; and also an important tool that can facilitate the organized expression of community needs and assist in setting democratic priorities of local development. There is no doubt that something new is emerging in various parts of the territory in Sao Paulo - the biggest city of Brazil, with over eleven billion people. It is remarkable that there is a growing desire and political will of the inhabitants to relinquish their passive attitudes and assume, collectively, the changes in favor of the creation of improved living conditions of the neighborhood. In an area comprising four neighborhoods of the west Sao Paulo it was identified three social experiences that follows singular paths, but have the same goal: promoting the improvement of the square nearby their homes and, thereby, encourage the use of public space. The aim of this report is to analyze these three social experiences and compare them with the concept of local development. To support this essay, it was made a literature review on the concept of Development and Local Development based, fundamentally, on the ideas of Amartya Sen, Ladislau Dowbor, Ignacy Sachs, Celso Furtado and Alain Lipietz. The author of this essay participated actively in the three social experiments from February to December 2010 producing 'thick descriptions' (GEERTZ, 1989) about the meetings, the dynamics of neighborhoods and squares and informal conversations with participants. This essay concludes that the square in the urban territory can symbolize the epicenter of local development
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