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Seuken, Sven

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Seuken

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Sven

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Seuken, Sven
Author's Publications: search.filters.isAuthorOfPublication.015040da-ad14-4b93-bbd0-ad3a568638e0

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Now showing 1 - 6 of 6
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    Sybil-proof Accounting Mechanisms with Transitive Trust
    (ACM, 2014) Seuken, Sven; Parkes, David
    For the design of distributed work systems like P2P filesharing networks it is essential to provide incentives for agents to work for each other rather than free ride. Several mechanisms have been proposed to achieve this goal, including currency systems, credit networks, and accounting mechanisms. It has proven particularly challenging to provide robustness to sybil attacks, i.e., attacks where an agent creates and controls multiple false identities. In this paper, we consider accounting mechanisms for domains in which (1) transactions cannot be bound to reports, (2) transactions are bilateral and private, and (3) agents can only form trust links upon successful work interactions. Our results reveal the trade-off one must make in designing such mechanisms. We show that accounting mechanisms with a strong form of transitive trust cannot be robust against strongly beneficial sybil attacks. However, we also present a mechanism that strikes a balance, providing a weaker form of transitive trust while also being robust against the strongest form of sybil attacks. On the one hand, our results highlight the role of strong social ties in providing robustness against sybil attacks (such as those leveraged in credit networks using bilateral IOUs), and on the other hand our results show what kind of robustness properties are possible and impossible in domains where such pre-existing trust relations do not exist.
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    Accounting Mechanisms for Distributed Work Systems
    (AAAI Press, 2010) Seuken, Sven; Tang, Jie; Parkes, David
    In distributed work systems, individual users perform work for other users. A significant challenge in these systems is to provide proper incentives for users to contribute as much work as they consume, even when monitoring is not possible. We formalize the problem of designing incentive-compatible accounting mechanisms that measure the net contributions of users, despite relying on voluntary reports. We introduce the Drop-Edge Mechanism that removes any incentive for a user to manipulate via misreports about work contributed or consumed. We prove that Drop-Edge provides a good approximation to a user’s net contribution, and is accurate in the limit as the number of users grows. We demonstrate very good welfare properties in simulation compared to an existing, manipulable mechanism. In closing, we discuss our ongoing work, including a real-world implementation and evaluation of the DropEdge Mechanism in a BitTorrent client.
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    Market User Interface Design
    (ACM Press, 2012) Seuken, Sven; Parkes, David; Horvitz, Eric; Jain, Kamal; Czerwinski, Mary; Tan, Desney
    Despite the pervasiveness of markets in our lives, little is known about the role of user interfaces (UIs) in promoting good decisions in market domains. How does the way we display market information to end users, and the set of choices we offer, influence users' decisions? In this paper, we introduce a new research agenda on "market user interface design." Our goal is to find the optimal market UI, taking into account that users incur cognitive costs and are boundedly rational. Via lab experiments we systematically explore the market UI design space, and we study the automatic optimization of market UIs given a behavioral (quantal response) model of user behavior. Surprisingly, we find that the behaviorally-optimized UI performs worse than the standard UI, suggesting that the quantal response model did not predict user behavior well. Subsequently, we identify important behavioral factors that are missing from the user model, including loss aversion and position effects, which motivates follow-up studies. Furthermore, we find significant differences between individual users in terms of rationality. This suggests future research on personalized UI designs, with interfaces that are tailored towards each individual user's needs, capabilities, and preferences.
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    Incentive-Compatible Escrow Mechanisms
    (American Association for Artificial Intelligence, 2011) Witkowski, Jens; Seuken, Sven; Parkes, David
    The most prominent way to establish trust between buyers and sellers on online auction sites are reputation mechanisms. Two drawbacks of this approach are the reliance on the seller being long-lived and the susceptibility to whitewashing. In this paper, we introduce so-called escrow mechanisms that avoid these problems by installing a trusted intermediary which forwards the payment to the seller only if the buyer acknowledges that the good arrived in the promised condition. We address the incentive issues that arise and design an escrow mechanism that is incentive compatible, efficient, interim individually rational and ex ante budget-balanced. In contrast to previous work on trust and reputation, our approach does not rely on knowing the sellers’ cost functions or the distribution of buyer valuations.
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    On the Sybil-Proofness of Accounting Mechanisms
    (Association for Computing Machinery, 2011) Seuken, Sven; Parkes, David
    A common challenge in distributed work systems like P2P file-sharing communities, or ad-hoc routing networks, is to minimize the number of free-riders and incentivize contributions. Without any centralized monitoring it is difficult to distinguish contributors from free-riders. One way to address this problem is via accounting mechanisms which rely on voluntary reports by individual agents and compute a score for each agent in the network. In Seuken et al. [11], we have recently proposed a mechanism which removes any incentive for a user to manipulate the mechanism via misreports. However, we left the existence of sybil-proof accounting mechanisms as an open question. In this paper, we settle this question, and show the striking impossibility result that under reasonable assumptions no sybil-proof accounting mechanism exists. We show, that a significantly weaker form of K-sybil-proofness can be achieved against certain classes of sybil attacks. Finally, we explain how limited robustness to sybil manipulations can be achieved by using max-flow algorithms in accounting mechanism design.
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    Handling Interdependent Values in an Auction Mechanism for Bandwidth Allocation in Tactical Data Networks
    (Association for Computing Machinery, 2008) Klein, Mark; Moreno, Gabriel A.; Parkes, David; Plakosh, Daniel; Seuken, Sven; Wallnau, Kurt C.
    We consider a tactical data network with limited bandwidth, in which each agent is tracking objects and may have value for receiving data from other agents. The agents are self-interested and would prefer to receive data than share data. Each agent has private information about the quality of its data and can misreport this quality and degrade or otherwise decline to share its data. The problem is one of interdependent value mechanism design because the value to one agent for the broadcast of data on an object depends on the quality of the data, which is privately known to the sender. A recent two-stage mechanism due to Mezzetti (2004) can be modified to our setting. Our mechanism achieves efficient bandwidth allocation and provides incentive compatibility by conditioning payments on the realized value for data shared between agents.