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An overview on smart contracts : Challenges, advances and platforms

Service Oriented Architecture Concepts Technology And Design

Mobile Opportunistic Network (MON) is characterized by intermittent connectivity where communication largely depends on the mobility pattern of the participating nodes. In MON, a node can take the custody of a packet for a long time and carry it until a new forwarding path has been established, unlike mobile adhoc network (MANET), where a node must drop the packet otherwise. Therefore, routing in MON depends on the repeated make-and-break of communication links, which again depends on the mobility of the nodes as they encounter and drift away from each other. MONs can simply be formed by humans carrying hand-held devices (like Personal Digital Assistant [PDAs] or cell phones) or on-board devices installed in vehicles. Therefore, with mobility playing a major role in the performance of MON, researchers have repeatedly tried to understand the nature of mobility with respect to humans, vehicles, and wild animals. To study the nature of mobility, researchers have collected mobility traces, proposed mobility models, and analyzed the performance of MON with respect to various mobility parameters. This article provides a detailed survey of different mobility models which have been proposed to date and how mobility largely determines the performance of opportunistic routing. We divide the article into four major sections. First, we provide a detailed survey of all the synthetic mobility models which have been developed to date. Second, we study the various mobility traces which have been collected and analyzed. Third, we study how mobility parameters affect the performance of MON. Finally, we highlight on some of the research areas and open challenges which yet remain unsolved.

Mobility Models, Traces and Impact of Mobility on Opportunistic Routing Algorithms: A Survey

At the core of the economic logic of cryptocurrencies lies the problem of surmounting the double-spending problem, which poses an accounting and accountability challenge that effective cryptocurrencies have sought to overcome. This discussion paper reviews the salient literature so as to better inform academic and practitioner inquiry on the double-spending problems in cryptocurrencies.

The Double Spending Problem and Cryptocurrencies

 The more intelligent systems based on sub-symbolic techniques pervade our everyday lives, the less human can understand them. This is why symbolic approaches are getting more and more attention in the general effort to make AI interpretable, explainable, and trustable. Understanding the current state of the art of AI techniques integrating symbolic and sub-symbolic approaches is then of paramount importance, nowadays—in particular in the XAI perspective. This is why this paper provides an overview of the main symbolic/sub-symbolic integration techniques, focussing in particular on those targeting explainable AI systems.

On the integration of symbolic and sub-symbolic techniques for XAI: A survey

Precisely when the success of artificial intelligence (AI) sub-symbolic techniques makes them be identified with the whole AI by many non-computer-scientists and non-technical media, symbolic approaches are getting more and more attention as those that could make AI amenable to human understanding. Given the recurring cycles in the AI history, we expect that a revamp of technologies often tagged as “classical AI”—in particular, logic-based ones—will take place in the next few years. On the other hand, agents and multi-agent systems (MAS) have been at the core of the design of intelligent systems since their very beginning, and their long-term connection with logic-based technologies, which characterised their early days, might open new ways to engineer explainable intelligent systems. This is why understanding the current status of logic-based technologies for MAS is nowadays of paramount importance. Accordingly, this paper aims at providing a comprehensive view of those technologies by making them the subject of a systematic literature review (SLR). The resulting technologies are discussed and evaluated from two different perspectives: the MAS and the logic-based ones.

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Logic-based technologies for multi-agent systems: a systematic literature review

Together with the disruptive development of modern sub-symbolic approaches to artificial intelligence (AI), symbolic approaches to classical AI are re-gaining momentum, as more and more researchers exploit their potential to make AI more comprehensible, explainable, and therefore trustworthy. Since logic-based approaches lay at the core of symbolic AI, summarizing their state of the art is of paramount importance now more than ever, in order to identify trends, benefits, key features, gaps, and limitations of the techniques proposed so far, as well as to identify promising research perspectives. Along this line, this paper provides an overview of logic-based approaches and technologies by sketching their evolution and pointing out their main application areas. Future perspectives for exploitation of logic-based technologies are discussed as well, in order to identify those research fields that deserve more attention, considering the areas that already exploit logic-based approaches as well as those that are more likely to adopt logic-based approaches in the future.

Logic-Based Technologies for Intelligent Systems: State of the Art and Perspectives

The testing of the performance of opportunistic communication protocols and applications is usually done through simulation as i) deployments are expensive and should be left to the final stage of the development process, and ii) the number of varying parameters in thesesystems is so high that it would be very hard to conduct thorough testing of all the functionality within a single deployment. Therefore, protocols and applications are often plugged into mobility simulators to test their performance; however, until recently, most of the testing has been conducted with random mobility models which do not mirror reality. Furthermore, despite disconnections playing a veryprominent role in the performance of any opportunistic mobile system, most models do not really account for it. A different approach to testing is the use of real traces of movement collected in specific domains as test cases. These cases, however, do not allow for flexible performance testing, as they are specific for a given scenario withfixed connectivity properties.In this paper we propose the Connectivity Trace Generator (CTG), a tool for the automatic generation of connectivity traces, which takes as input real mobility traces and is able to output a set of traces with similar connectivity properties, which can be used as test cases. This allows developers to investigate the impact of the variation of connectivity patterns, number of hosts, and other parameters on the protocol or application under investigation.We use a real case study (the Dartmouth campus connectivity traces) to show how CTG allows protocol developers to play with some connectivity and density parameters so to best conduct performance testing of different aspects of protocols and applications.

/pdf/ctg-a-connectivity-trace-generator-for-testing-the-fruioenqud.pdf

CTG: a connectivity trace generator for testing the performance of opportunistic mobile systems

The blockchain is a novel approach to support distributed systems enabling a common, consistent view of a shared state among distributed nodes. There, smart contracts are computer programs that allow users to deploy arbitrary computations, in charge of automatically regulate state transitions and enforce properties. In this paper we speculate on how the blockchain and smart contracts could take advantage of a logic programming approach, and, complementarily, on how logic programming can benefit from the blockchain infrastructure. Accordingly, we discuss some possible research directions and open questions for future research.

/pdf/from-the-blockchain-to-logic-programming-and-back-research-59l2pqrinl.pdf

Roberta Calegari

Papers

On the integration of symbolic and sub-symbolic techniques for XAI: A survey

Logic-based technologies for multi-agent systems: a systematic literature review

Logic-Based Technologies for Intelligent Systems: State of the Art and Perspectives

CTG: a connectivity trace generator for testing the performance of opportunistic mobile systems

From the Blockchain to Logic Programming and Back: Research Perspectives