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35
Rationality and SelfInterest in Peer to Peer Networks
 IN 2ND INT. WORKSHOP ON PEERTOPEER SYSTEMS (IPTPS’03)
, 2003
"... Much of the existing work in peer to peer networking assumes that users will follow prescribed protocols without deviation. This assumption ignores the user's ability to modify the behavior of an algorithm for selfinterested reasons. ..."
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Cited by 101 (10 self)
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Much of the existing work in peer to peer networking assumes that users will follow prescribed protocols without deviation. This assumption ignores the user's ability to modify the behavior of an algorithm for selfinterested reasons.
An analysis of alternative slot auction designs for sponsored search
 In Proceedings of the 7th ACM conference on Electronic commerce
, 2006
"... Billions of dollars are spent each year on sponsored search, a form of advertising where merchants pay for placement alongside web search results. Slots for ad listings are allocated via an auctionstyle mechanism where the higher a merchant bids, the more likely his ad is to appear above other ads ..."
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Cited by 98 (6 self)
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Billions of dollars are spent each year on sponsored search, a form of advertising where merchants pay for placement alongside web search results. Slots for ad listings are allocated via an auctionstyle mechanism where the higher a merchant bids, the more likely his ad is to appear above other ads on the page. In this paper we analyze the incentive, efficiency, and revenue properties of two slot auction designs: “rank by bid ” (RBB) and “rank by revenue” (RBR), which correspond to stylized versions of the mechanisms currently used by Yahoo! and Google, respectively. We also consider first and secondprice payment rules together with each of these allocation rules, as both have been used historically. We consider both the “shortrun ” incomplete information setting and the “longrun ” complete information setting. With incomplete information, neither RBB nor RBR are truthful with either first or second pricing. We find that the informational requirements of RBB are much weaker than those of RBR, but that RBR is efficient whereas RBB is not. We also show that no revenue ranking of RBB and RBR is possible given an arbitrary distribution over bidder values and relevance. With complete information, we find that no equilibrium exists with first pricing using either RBB or RBR. We show that there typically exists a multitude of equilibria with second pricing, and we bound the divergence of (economic) value in such equilibria from the value obtained assuming all merchants bid truthfully.
Specification Faithfulness in Networks with Rational Nodes
, 2004
"... It is useful to prove that an implementation correctly follows a specification. But even with a provably correct implementation, given a choice, would a node choose to follow it? This paper explores how to create distributed system specifications that will be faithfully implemented in networks with ..."
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Cited by 72 (11 self)
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It is useful to prove that an implementation correctly follows a specification. But even with a provably correct implementation, given a choice, would a node choose to follow it? This paper explores how to create distributed system specifications that will be faithfully implemented in networks with rational nodes, so that no node will choose to deviate. Given a strategyproof centralized mechanism, and given a network of nodes modeled as having rationalmanipulation faults, we provide a proof technique to establish the incentive, communication, and algorithmcompatibility properties that guarantee that participating nodes are faithful to a suggested specification. As a case study, we apply our methods to extend the strategyproof interdomain routing mechanism proposed by Feigenbaum, Papadimitriou, Sami, and Shenker (FPSS) [7], defining a faithful implementation.
Greedy bidding strategies for keyword auctions
 In Eighth ACM Conference on Electronic Commerce
, 2007
"... How should players bid in keyword auctions such as those used by Google, Yahoo! and MSN? We consider greedy bidding strategies for a repeated auction on a single keyword, where in each round, each player chooses some optimal bid for the next round, assuming that the other players merely repeat their ..."
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Cited by 70 (8 self)
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How should players bid in keyword auctions such as those used by Google, Yahoo! and MSN? We consider greedy bidding strategies for a repeated auction on a single keyword, where in each round, each player chooses some optimal bid for the next round, assuming that the other players merely repeat their previous bid. We study the revenue, convergence and robustness properties of such strategies. Most interesting among these is a strategy we call the balanced bidding strategy (bb): it is known that bb has a unique fixed point with payments identical to those of the VCG mechanism. We show that if all players use the bb strategy and update each round, bb converges when the number of slots is at most 2, but does not always converge for 3 or more slots. On the other hand, we present a simple variant which is guaranteed to converge to the same fixed point for any number of slots. In a model in which only one randomly chosen player updates each round according to the bb strategy, we prove that convergence occurs with probability 1. We complement our theoretical results with empirical studies. 1.
Faithfulness in Internet Algorithms
 SIGCOMM '04
, 2004
"... Proving or disproving faithfulness (a property describing robustness to rational manipulation in action as well as information revelation) is an appealing goal when reasoning about distributed systems containing rational participants. Recent work formalizes the notion of faithfulness and its founda ..."
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Cited by 43 (4 self)
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Proving or disproving faithfulness (a property describing robustness to rational manipulation in action as well as information revelation) is an appealing goal when reasoning about distributed systems containing rational participants. Recent work formalizes the notion of faithfulness and its foundation properties, and presents a general proof technique in the course of proving the ex post Nash faithfulness of a theoretical routing problem [11]. In this paper, we use a less formal approach and take some first steps in faithfulness analysis for existing algorithms running on the Internet. To this end, we consider the expected faithfulness of BitTorrent, a popular file download system, and show how manual backtracing (similar to the the ideas behind program slicing [22]) can be used to find rational manipulation problems. Although this primitive technique has serious drawbacks, it can be useful in disproving faithfulness. Building provably faithful Internet protocols and their corresponding specifications can be quite difficult depending on the system knowledge assumptions and problem complexity. We present some of the open problems that are associated with these challenges.
Fully Private Auctions in a constant number of rounds
, 2002
"... We present a new cryptographic auction protocol that prevents extraction of bid information despite any collusion of participants. This requirement is stronger than common assumptions in existing protocols that prohibit the collusion of certain thirdparties (e.g. distinct auctioneers) . Full privac ..."
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Cited by 39 (7 self)
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We present a new cryptographic auction protocol that prevents extraction of bid information despite any collusion of participants. This requirement is stronger than common assumptions in existing protocols that prohibit the collusion of certain thirdparties (e.g. distinct auctioneers) . Full privacy is obtained by using homomorphic encryption (e.g. ElGamal) and distributing the private key among the set of bidders. Bidders jointly compute the auction outcome on their own without uncovering any additional information in a constant number of rounds. No auctioneers or other trusted third parties are needed to resolve the auction. Yet, robustness is assured due to public verifiability of the entire protocol. The scheme can be applied to any uniformprice (or socalled (M + 1)stprice) auction. To the best of our knowledge, there is no other cryptographic auction protocol that achieves a similar level of privacy. The selling price is only revealed to the seller and the winning bidders themselves. In addition, we propose schemes that require more rounds but are computationally much more e#cient. 1
A verifiable, bidderresolved Auction Protocol
 In Proceedings of the 5th International Workshop on Deception, Fraud and Trust in Agent Societies
, 2002
"... Security and privacy have become crucial factors in auction design. Various schemes to ensure the safe conduction of sealedbid auctions have been proposed recently. We introduce a new standard of privacy for auctions ("full privacy"), that prevents extraction of bid information despite an ..."
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Cited by 30 (5 self)
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Security and privacy have become crucial factors in auction design. Various schemes to ensure the safe conduction of sealedbid auctions have been proposed recently. We introduce a new standard of privacy for auctions ("full privacy"), that prevents extraction of bid information despite any collusion of participants. This requirement is stronger than other common assumptions that prohibit the collusion of certain thirdparties (e.g., distinct auctioneers). Full privacy can be obtained by applying a secret sharing scheme in which the bidders jointly compute the selling price on their own without uncovering any additional information. No auctioneers or other trusted third parties are used to resolve the auction.
Sponsored search: an overview of the concept, history, and technology
"... Abstract: The success of sponsored search has radically affected how people interact with the information, websites, and services on the web. Sponsored search provides the necessary revenue streams to web search engines and is critical to the success of many online businesses. However, there has bee ..."
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Cited by 29 (7 self)
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Abstract: The success of sponsored search has radically affected how people interact with the information, websites, and services on the web. Sponsored search provides the necessary revenue streams to web search engines and is critical to the success of many online businesses. However, there has been limited academic examination of sponsored search, with the exception of online auctions. In this paper, we conceptualise the sponsored search process as an aspect of information searching. We provide a brief history of sponsored search and an extensive examination of the technology making sponsored search possible. We critique this technology, highlighting possible implications for the future of the sponsored search process.
Altruism, selfishness, and spite in traffic routing
 In Proc. 9th Conf. Electronic Commerce (EC
, 2008
"... In this paper, we study the price of anarchy of traffic routing, under the assumption that users are partially altruistic or spiteful. We model such behavior by positing that the “cost ” perceived by a user is a linear combination of the actual latency of the route chosen (selfish component), and th ..."
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Cited by 24 (4 self)
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In this paper, we study the price of anarchy of traffic routing, under the assumption that users are partially altruistic or spiteful. We model such behavior by positing that the “cost ” perceived by a user is a linear combination of the actual latency of the route chosen (selfish component), and the increase in latency the user causes for others (altruistic component). We show that if all users have a coefficient of at least β> 0 for the altruistic component, then the price of anarchy is bounded by 1/β, for all network topologies, arbitrary commodities, and arbitrary semiconvex latency functions. We extend this result to give more precise bounds on the price of anarchy for specific classes of latency functions, even for β < 0 modeling spiteful behavior. In particular, we show that if all latency functions are linear, the price of anarchy is bounded by 4/(3 + 2β − β 2). We next study nonuniform altruism distributions, where different users may have different coefficients β. We prove that all such games, even with infinitely many types of players, have a Nash Equilibrium. We show that if the average of the coefficients for the altruistic components of all users is ¯ β, then the price of anarchy is bounded by 1 / ¯ β, for single commodity parallel link networks, and arbitrary convex latency functions. In particular, this result generalizes, albeit nonconstructively, the Stackelberg routing results of Roughgarden and of Swamy. More generally, we bound the price of anarchy based on the class of allowable latency functions, and as a corollary obtain tighter bounds for Stackelberg routing than a recent result of Swamy.
Computing bestresponse strategies in infinite games of incomplete information
 In Uncertainty in artificial intelligence
, 2004
"... We describe an algorithm for computing bestresponse strategies in a class of twoplayer infinite games of incomplete information, defined by payoffs piecewise linear in agents ’ types and actions, conditional on linear comparisons of agents ’ actions. We show that this class includes many wellknown ..."
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Cited by 22 (5 self)
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We describe an algorithm for computing bestresponse strategies in a class of twoplayer infinite games of incomplete information, defined by payoffs piecewise linear in agents ’ types and actions, conditional on linear comparisons of agents ’ actions. We show that this class includes many wellknown games including a variety of auctions and a novel allocation game. In some cases, the bestresponse algorithm can be iterated to compute BayesNash equilibria. We demonstrate the efficacy of our approach on existing and new games. 1