34,406 research outputs found

    From Agent Game Protocols to Implementable Roles

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    kostas.stathis-at-cs.rhul.ac.uk Abstract. We present a formal framework for decomposing agent interaction protocols to the roles their participants should play. The framework allows an Authority Agent that knows a protocol to compute the protocol’s roles so that it can allocate them to interested parties. We show how the Authority Agent can use the role descriptions to identify problems with the protocol and repair it on the fly, to ensure that participants will be able to implement their role requirements without compromising the protocol’s interactions. Our representation of agent interaction protocols is a game-based one and the decomposition of a game protocol into its constituent roles is based upon the branching bisimulation equivalence reduction of the game. The work extends our previous work on using games to admit agents in an artificial society by checking their competence according to the society rules. The applicability of the overall approach is illustrated by showing how to decompose the NetBill protocol into its roles. We also show how to automatically repair the interactions of a protocol that cannot be implemented in its original form.

    Federated Embedded Systems – a review of the literature in related fields

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    This report is concerned with the vision of smart interconnected objects, a vision that has attracted much attention lately. In this paper, embedded, interconnected, open, and heterogeneous control systems are in focus, formally referred to as Federated Embedded Systems. To place FES into a context, a review of some related research directions is presented. This review includes such concepts as systems of systems, cyber-physical systems, ubiquitous computing, internet of things, and multi-agent systems. Interestingly, the reviewed fields seem to overlap with each other in an increasing number of ways

    Blockchain For Food: Making Sense of Technology and the Impact on Biofortified Seeds

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    The global food system is under pressure and is in the early stages of a major transition towards more transparency, circularity, and personalisation. In the coming decades, there is an increasing need for more food production with fewer resources. Thus, increasing crop yields and nutritional value per crop is arguably an important factor in this global food transition. Biofortification can play an important role in feeding the world. Biofortified seeds create produce with increased nutritional values, mainly minerals and vitamins, while using the same or less resources as non-biofortified variants. However, a farmer cannot distinguish a biofortified seed from a regular seed. Due to the invisible nature of the enhanced seeds, counterfeit products are common, limiting wide-scale adoption of biofortified crops. Fraudulent seeds pose a major obstacle in the adoption of biofortified crops. A system that could guarantee the origin of the biofortified seeds is therefore required to ensure widespread adoption. This trust-ensuring immutable proof for the biofortified seeds, can be provided via blockchain technology

    Defending Against Firmware Cyber Attacks on Safety-Critical Systems

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    In the past, it was not possible to update the underlying software in many industrial control devices. Engineering teams had to ‘rip and replace’ obsolete components. However, the ability to make firmware updates has provided significant benefits to the companies who use Programmable Logic Controllers (PLCs), switches, gateways and bridges as well as an array of smart sensor/actuators. These updates include security patches when vulnerabilities are identified in existing devices; they can be distributed by physical media but are increasingly downloaded over Internet connections. These mechanisms pose a growing threat to the cyber security of safety-critical applications, which are illustrated by recent attacks on safety-related infrastructures across the Ukraine. Subsequent sections explain how malware can be distributed within firmware updates. Even when attackers cannot reverse engineer the code necessary to disguise their attack, they can undermine a device by forcing it into a constant upload cycle where the firmware installation never terminates. In this paper, we present means of mitigating the risks of firmware attack on safety-critical systems as part of wider initiatives to secure national critical infrastructures. Technical solutions, including firmware hashing, must be augmented by organizational measures to secure the supply chain within individual plants, across companies and throughout safety-related industries

    A visible geography of invisible journeys: Central American migration and the politics of survival

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    Human rights groups have called undocumented Central American migrants the ‘invisible victims’ of criminal violence in Mexico. However, the geography of the unauthorised migration route through Mexico is highly visible; its location, protocols and violent practices constitute common knowledge in the communities through which it cuts its path. This paper examines the visual cues of the route. Images of places, such as the trailhead, the river at the borders, the migrant shelter and the train yard, provide focal points that orient migrants to the physical terrain. These images also orient activists, providing potent symbols for political contestation in favour of migrants’ rights. However, visibility attracts criminal gangs who rob, kidnap and rape migrants, and the gaze of state officials who detain and deport migrants. Thus, this paper traces how geographic icons become beacons to migrants, activists, criminal predators and state actors, and it examines the nature of information and representation under this strategic interaction. It examines how victims and perpetrators become visible to one another

    Using Flow Specifications of Parameterized Cache Coherence Protocols for Verifying Deadlock Freedom

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    We consider the problem of verifying deadlock freedom for symmetric cache coherence protocols. In particular, we focus on a specific form of deadlock which is useful for the cache coherence protocol domain and consistent with the internal definition of deadlock in the Murphi model checker: we refer to this deadlock as a system- wide deadlock (s-deadlock). In s-deadlock, the entire system gets blocked and is unable to make any transition. Cache coherence protocols consist of N symmetric cache agents, where N is an unbounded parameter; thus the verification of s-deadlock freedom is naturally a parameterized verification problem. Parametrized verification techniques work by using sound abstractions to reduce the unbounded model to a bounded model. Efficient abstractions which work well for industrial scale protocols typically bound the model by replacing the state of most of the agents by an abstract environment, while keeping just one or two agents as is. However, leveraging such efficient abstractions becomes a challenge for s-deadlock: a violation of s-deadlock is a state in which the transitions of all of the unbounded number of agents cannot occur and so a simple abstraction like the one above will not preserve this violation. In this work we address this challenge by presenting a technique which leverages high-level information about the protocols, in the form of message sequence dia- grams referred to as flows, for constructing invariants that are collectively stronger than s-deadlock. Efficient abstractions can be constructed to verify these invariants. We successfully verify the German and Flash protocols using our technique
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