679 research outputs found

    Blockchain Software Verification and Optimization

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    In the last decade, blockchain technology has undergone a strong evolution. The maturity reached and the consolidation obtained have aroused the interest of companies and businesses, transforming it into a possible response to various industrial needs. However, the lack of standards and tools for the development and maintenance of blockchain software leaves open challenges and various possibilities for improvements. The goal of this thesis is to tackle some of the challenges proposed by blockchain technology, to design and implement analysis, processes, and architectures that may be applied in the real world. In particular, two topics are addressed: the verification of the blockchain software and the code optimization of smart contracts. As regards the verification, the thesis focuses on the original developments of tools and analyses able to detect statically, i.e. without code execution, issues related to non-determinism, untrusted cross-contracts invocation, and numerical overflow/underflow. Moreover, an approach based on on-chain verification is investigated, to proactively involve the blockchain in verifying the code before and after its deployment. For the optimization side, the thesis describes an optimization process for the code translation from Solidity language to Takamaka, also proposing an efficient algorithm to compute snapshots for fungible and non-fungible tokens. The results of this thesis are an important first step towards improving blockchain software development, empirically demonstrating the applicability of the proposed approaches and their involvement also in the industrial field

    Antonio Invernizzi (Turin, 1 January 1941 – 2 December 2021)

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    Obituary Prof. Antonio Invernizzi UniversitĂ  di Torin

    Archaeological Evidence for a Climatic and Agrarian Crisis in Swat between 530 and 660: Possible Effects of the So-called “Late Antique Little Ice Age” (LALIA)

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    The short article evaluates the possible impacts of the Late Antique Little Ice Age (LALIA)—a long cooling period that occurred between 536 and 660 CE in the adjacent regions of Inner Asia (BĂŒntigen et al. 2016; Whittow 2019). The high mountain valley of Swat in Pakistan potentially experienced a collapse of agro-production with dramatic implications for the Buddhist society, which began a long and inexorable decline around the mid-6th century

    The effect of the Basset history force on particle clustering in Homogeneous and Isotropic Turbulence

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    We study the effect of the Basset history force on the dynamics of small particles transported in homogeneous and isotropic turbulence and show that this term, often neglected in previous numerical studies, reduces the small-scale clustering typical of inertial particles. The contribution of this force to the total particle acceleration is, on average, responsible for about 10% of the total acceleration and particularly relevant during rare strong events. At moderate density ratios, i.e. sand or metal powder in water, its presence alters the balance of forces determining the particle acceleration

    Patterns of Early Urbanisation in Swat: A Reassessment of the Data from the Recent Excavations at Barikot

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    The study presents a set of new data, all coming from recent excavations in the ancient urban site of Barikot (Swat, Pakistan), which may allow a new look at phenomena hitherto considered certain, such as the delay of protohistoric phases, the so-called marginalization of Swat, and the beginning of urban phases seen in association with the Indo-Greek colonial power. In our reconstruction, the protohistoric phases end around 800 BCE, while, after a phase of negative interface, i.e. of significant abandonment, towards the middle of the first millennium, there are conditions for the establishment of an urban settlement in Barikot. At this stage, very significantly, for the first time, the local ceramic tradition is replaced by Gangetic and Iranian forms, which are interpreted as markers of a growing process of trans-regional trade relations. In this ongoing process of historical reconstruction, the silence of the archaeological component towards the so-called Mauryan phase, of which field archaeology has not yet managed to provide a clear picture, remains strident

    The View from Malakand: Harold Deane's 'Note on Udyana and Gandhara'

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    The View from Malakand: Harold Deane's 'Note on Udyana and Gandhara' presents an edition with introductions and extensive commentary of a manuscript, discovered by Luca M. Olivieri in the fort at Malakand, Swat, Pakistan, of a seminal and pioneering account of the antiquities of Swat and Peshawar by Harold Deane. The article of which this manuscript is an earlier draft, the first significant contribution to the archaeology of Swat, was published in the Journal of the Asiatic Society (1896), and the manuscript contains interesting additional information that did not make the final text. The book presents and transcribes the manuscript, also including introductory material on its discovery and the life and significance of Deane, and (most importantly) extended notes identifying and describing the places that Deane discusses in his article. The book thus doubles as a gazetteer of this immensely rich archaeological space, and a history of its archaeological discovery. The book includes images of the original article, the manuscript, some of the artefacts referred to by Deane in his article, and an appendix publishing a manuscript by J. W. McCrindle, 'Alexander's Campaign in Afghanistan', found among a small number of Deane's papers in the possession of his great-grandson in England, which is directly relevant to the composition of his article

    On-Chain Smart Contract Verification over Tendermint

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    Smart contracts are computer code that runs in blockchain and expresses the rules of an agreement among parties. A bug in their code has major consequences, such as rule violations and security attacks. Smart contracts are immutable and cannot be easily replaced to patch a bug. To overcome these problems, there exist automatic static analyzers that find bugs before smart contracts are installed in blockchain. However, this off-chain verification is optional: programmers are not forced to use it. This paper defines on-chain verification instead, that occurs inside the same blockchain nodes, when the code of smart contracts is installed. It acts as a mandatory entry filter that bans code that does not abide to the verification rules, that are consequently part of the consensus rules of the blockchain. Thus, an improvement in on-chain verification entails a consensus update of the network. This paper provides an implementation of on-chain verification for smart contracts written in the Takamaka subset of Java, running as a Tendermint application. It shows that on-chain verification works, reporting actual experiments

    Swat after the Indo‑Greeks. The City, the Sanctuaries and the Economy. An Archaeological Overview on the Saka‑Parthian period

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    The article presents an overview of the archaeological data (updated to 2021) from the recent excavations at Barikot, Swat (Pakistan), and preliminary results from ongoing studies of the other archaeological evidence related to the post‑Indo‑Greek phases in Swat and Gandhara (ca. 50 BC–50 AD). The article introduces some of the most distinctive markers of material culture in this context, as well as the evidence of new fortifications and building activity both in urban centres and Buddhist sanctuaries. The data collected thus far underpin a new interpretation of this little‑known historical phase of ancient northwestern India. The phase is characterized by a building program and political vibrancy, which do not correspond with the model of an economic recession advanced by scholars thus far. Indeed, in this framework, the so‑called ‘Great Debasement’ attributed to Azes II, might have had alternative implications

    Cybersecurity Impacts of the Covid-19 Pandemic in Italy

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    The Covid-19 pandemic has pushed companies to the extensive use of digital services, to implement home working and provide online services to people in lockdown. As a consequence, it is interesting to study how this has affected the number, kind and distribution of cybersecurity attacks. This paper gives an empirical evaluation of the cybersecurity attacks at the beginning of the Covid-19 pandemic in Italy, based on data collected from the questionnaires of the annual Digital Attacks Observatory. It shows that the overall number of attacks has not increased, but attacks have affected smaller companies than before. This can be explained with the fact that the Italian industrial scenario is mostly populated by small and medium enterprises, that have been obliged to a quick reconversion of their IT systems and typically lack the necessary cybersecurity culture