221,845 research outputs found

    Evolutionary games on multilayer networks: A colloquium

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    Networks form the backbone of many complex systems, ranging from the Internet to human societies. Accordingly, not only is the range of our interactions limited and thus best described and modeled by networks, it is also a fact that the networks that are an integral part of such models are often interdependent or even interconnected. Networks of networks or multilayer networks are therefore a more apt description of social systems. This colloquium is devoted to evolutionary games on multilayer networks, and in particular to the evolution of cooperation as one of the main pillars of modern human societies. We first give an overview of the most significant conceptual differences between single-layer and multilayer networks, and we provide basic definitions and a classification of the most commonly used terms. Subsequently, we review fascinating and counterintuitive evolutionary outcomes that emerge due to different types of interdependencies between otherwise independent populations. The focus is on coupling through the utilities of players, through the flow of information, as well as through the popularity of different strategies on different network layers. The colloquium highlights the importance of pattern formation and collective behavior for the promotion of cooperation under adverse conditions, as well as the synergies between network science and evolutionary game theory.Comment: 14 two-column pages, 8 figures; accepted for publication in European Physical Journal

    Evaluation of an Internet Document Delivery Service

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    An Internet-based Document Delivery Service (DDS) has been developed within the framework of the CNR ( the Italian Research National Council) Project BiblioMIME, in order to take advantage of new Internet technologies and promote cooperation among CNR and Italian university libraries. Adopting such technologies changes the traditional organisation of DDS and may drastically reduce costs and delivery times. An information system managing DDS requests and monitoring the temporal evolution of the service has been implemented, running on the local-area network of a test-site library. It aims to track number and types of documents requested and received, user distribution, delivery times and types (surface mail, fax, Internet), to automate repetitive manual procedures and to deal with the various accounting methods used by other libraries. Transmission of documents is carried out by means of an e-mail/Web gateway system supporting document exchange via Internet, which assists receiving libraries in retrieving requested documents. This paper describes the architecture and main design features of the e-mail/Web gateway server (the BiblioMime server). This approach permits librarians to continue using e-mail service to send large documents, while resolving problems that users may encounter when downloading large size files with e-mail agents. The library operator sends the document as an attachment to the destination address; on fly the e-mail server extracts and saves the attachments in a web-server disk file and substitutes them with a new message part that includes an URL pointing to the saved document. The receiver can download these large objects by means of a user-friendly browser. We further discuss the data gathered during the triennium 1998-2000; this consists of about 5,000 DDS transactions per annum with 300 other Italian scientific and bio-medical libraries and commercial document suppliers. Use of the instruments described above allowed us to evaluate the performance of service “before” and “after” the use of Internet Document Delivery and to extract some critical data regarding DDS. Those include: a) libraries with which we have greater numbers of exchanges and their turnaround times; b) extraordinary reduction in costs and delivery times; c) the most frequently requested serial titles (allowing cost-effective decisions on new subscriptions); d) impact on DDS of library participation in consortia which allow user access to greater numbers of online serials

    Cooperation techniques between LTE in unlicensed spectrum and Wi-Fi towards fair spectral efficiency

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    On the road towards 5G, a proliferation of Heterogeneous Networks (HetNets) is expected. Sensor networks are of great importance in this new wireless era, as they allow interaction with the environment. Additionally, the establishment of the Internet of Things (IoT) has incredibly increased the number of interconnected devices and consequently the already massive wirelessly transmitted traffic. The exponential growth of wireless traffic is pushing the wireless community to investigate solutions that maximally exploit the available spectrum. Recently, 3rd Generation Partnership Project (3GPP) announced standards that permit the operation of Long Term Evolution (LTE) in the unlicensed spectrum in addition to the exclusive use of the licensed spectrum owned by a mobile operator. Alternatively, leading wireless technology developers examine standalone LTE operation in the unlicensed spectrum without any involvement of a mobile operator. In this article, we present a classification of different techniques that can be applied on co-located LTE and Wi-Fi networks. Up to today, Wi-Fi is the most widely-used wireless technology in the unlicensed spectrum. A review of the current state of the art further reveals the lack of cooperation schemes among co-located networks that can lead to more optimal usage of the available spectrum. This article fills this gap in the literature by conceptually describing different classes of cooperation between LTE and Wi-Fi. For each class, we provide a detailed presentation of possible cooperation techniques that can provide spectral efficiency in a fair manner

    Metric clusters in evolutionary games on scale-free networks

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    The evolution of cooperation in social dilemmas in structured populations has been studied extensively in recent years. Whereas many theoretical studies have found that a heterogeneous network of contacts favors cooperation, the impact of spatial effects in scale-free networks is still not well understood. In addition to being heterogeneous, real contact networks exhibit a high mean local clustering coefficient, which implies the existence of an underlying metric space. Here, we show that evolutionary dynamics in scale-free networks self-organize into spatial patterns in the underlying metric space. The resulting metric clusters of cooperators are able to survive in social dilemmas as their spatial organization shields them from surrounding defectors, similar to spatial selection in Euclidean space. We show that under certain conditions these metric clusters are more efficient than the most connected nodes at sustaining cooperation and that heterogeneity does not always favor--but can even hinder--cooperation in social dilemmas. Our findings provide a new perspective to understand the emergence of cooperation in evolutionary games in realistic structured populations

    Features, operation principle and limits of SPI and I2C communication protocols for smart objects: a novel SPI-based hybrid protocol especially suitable for IoT applications

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    The Internet of Things (IoT) is an expression, sometimes abused by companies given the absence of an unambiguous meaning, that indicates the upcoming evolution of Internet as it has been known so far. In fact, all objects will have network capabilities which will be exploited to overcome, in certain situations, human intervention. Thanks to the direct cooperation of new class of devices, aware of their operating scenario and interconnected in subnetworks, our life style will be strongly enhanced and simplified. IoT, however, is not yet the “El Dorado” of technology, capable of revolutionizing everyday life: some aspects and open issues have to be carefully analyzed. The huge complexity of this new technology forces companies to select a specific research field: for this reason, they focus only on some features that an IoT device should have to guarantee fulfillment of requirements. In this context, this research work concerns an analysis of features, operation principle and limits of SPI and I2C communication protocols followed by the proposal of a new hybrid protocol suited for embedded systems, named FlexSPI, thought as an evolution of the classic SPI. Thanks to a robust software architecture, it is able to provide many features that can be used by smart objects to enhance their capabilities. In this way, sensors and actuators or, more in general, subsystems, can quickly exchange data and efficiently react to malfunctioning; moreover, number of devices on bus can be safely increased even while smart object is performing operations

    Why is IPv6 Deployment Important for the Internet Evolution?, Journal of Telecommunications and Information Technology, 2011, nr 2

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    Replacing the IPv4 protocol with IPv6 on the Internet is currently one of the aims of the European Union policy. The main reason for this replacement is the effeteness of the addresses pool in the IPv4 protocol, which can cause serious complications in the evolution of the Internet and its adaptation in new areas, e.g., in next generation mobile telephony or the so called Internet of Things. Simultaneously, the addressing capabilities of the IPv6 protocol are practically unlimited and its new functionalities increase the attractiveness of its usage. The article discusses the problems connected with the IPv6 deployment on the Internet. Especially, the rules for realization of the IPv6 deployment and rules for cooperation of IPv4 with IPv6 (including cooperation tests) in network infrastructure and in applications are presented. Moreover, the European projects’ results and the activity’s directions of the national project Future Internet Engineering are discussed

    ICANN—Now and Then: ICANN’s Reform and Its Problems

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    This paper sheds some light upon the major problem arising from the current normative infrastructure of the DNS and provides a possible solution to the current physical problem of the DNS. The paper\u27s main focus is the single-entity control of the A Root. The paper uses as a starting point the Blueprint prepared by the Committee on ICANN Evolution and Reform and raises the question: Has this reform done anything to resolve the single-entity control of the A Root? The paper argues that the reform has done nothing to solve the problem because the international privatization of the DNS merely substitutes the administration of the DNS function without making changes to the normative infrastructure of the DNS. In light of the above, the paper argues that there is a need to declare independence from a one-entity controlled DNS. The suggested approach is to share authority over the root by acknowledging that countries that are accountable to their populations are the authorities for their own ccTLDs. Once technical and political independence has been achieved, the technical and, to some degree, political management of the DNS should be exercised through an international body. In order to initiate a discussion for a truly international body this paper offers nine principles that a new international ccTLD cooperation organization should observe when working on its own creation

    Collective navigation of complex networks: Participatory greedy routing

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    Many networks are used to transfer information or goods, in other words, they are navigated. The larger the network, the more difficult it is to navigate efficiently. Indeed, information routing in the Internet faces serious scalability problems due to its rapid growth, recently accelerated by the rise of the Internet of Things. Large networks like the Internet can be navigated efficiently if nodes, or agents, actively forward information based on hidden maps underlying these systems. However, in reality most agents will deny to forward messages, which has a cost, and navigation is impossible. Can we design appropriate incentives that lead to participation and global navigability? Here, we present an evolutionary game where agents share the value generated by successful delivery of information or goods. We show that global navigability can emerge, but its complete breakdown is possible as well. Furthermore, we show that the system tends to self-organize into local clusters of agents who participate in the navigation. This organizational principle can be exploited to favor the emergence of global navigability in the system.Comment: Supplementary Information and Videos: https://koljakleineberg.wordpress.com/2016/11/14/collective-navigation-of-complex-networks-participatory-greedy-routing

    Research on the Sustainability of the Enterprise Business Ecosystem from the Perspective of Boundary:The China Case

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    In the context of the Internet, the business environment shows great uncertainty. This kind of uncertainty has not only changed the original competitive boundary of enterprise completely, but also the competition rules of enterprise. The cooperation of enterprises with suppliers, producers, sellers, customers, other organizations and stakeholders is getting closer and closer. The competition among enterprises is no longer the competition between individual enterprises, but based on the co-evolution under the business ecosystem. Therefore, how to create a good business ecosystem and sustainable development is the main problem faced by enterprises. This paper conducts an exploratory case study on the sustainability of the business ecosystem of enterprises from the perspective of boundary, to provide a new theoretical basis for the sustainable development of enterprises. This study investigates the specific impact of various system elements on the sustainable development of enterprises, summarizes the theoretical model, and finally provides feasible suggestions on promoting the sustainable development of the business ecosystem from the perspective of boundary
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