6,869 research outputs found

    Smoothness for Simultaneous Composition of Mechanisms with Admission

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    We study social welfare of learning outcomes in mechanisms with admission. In our repeated game there are nn bidders and mm mechanisms, and in each round each mechanism is available for each bidder only with a certain probability. Our scenario is an elementary case of simple mechanism design with incomplete information, where availabilities are bidder types. It captures natural applications in online markets with limited supply and can be used to model access of unreliable channels in wireless networks. If mechanisms satisfy a smoothness guarantee, existing results show that learning outcomes recover a significant fraction of the optimal social welfare. These approaches, however, have serious drawbacks in terms of plausibility and computational complexity. Also, the guarantees apply only when availabilities are stochastically independent among bidders. In contrast, we propose an alternative approach where each bidder uses a single no-regret learning algorithm and applies it in all rounds. This results in what we call availability-oblivious coarse correlated equilibria. It exponentially decreases the learning burden, simplifies implementation (e.g., as a method for channel access in wireless devices), and thereby addresses some of the concerns about Bayes-Nash equilibria and learning outcomes in Bayesian settings. Our main results are general composition theorems for smooth mechanisms when valuation functions of bidders are lattice-submodular. They rely on an interesting connection to the notion of correlation gap of submodular functions over product lattices.Comment: Full version of WINE 2016 pape

    Best Foot Forward or Best for Last in a Sequential Auction?

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    Should an informed seller of multiple goods sell the best goods first to make a favorable impression on buyers, or instead hold back on the best goods until buyers have learned more from earlier sales? To help answer this question we consider the sequential auction of two goods by a seller with private information about their values. We find that the seller's sequencing strategy endogenously generates correlation in the values of the goods across periods, thereby giving the seller an incentive to impress buyers by leading with the better good. This impression effect implies that selling the better good first is the unique equilibrium in many situations, and that selling the better good last is never a unique equilibrium. Nevertheless, if the seller could commit to a sequencing strategy, revenues would often be higher from waiting to sell the better good last. Either sequencing strategy reveals the seller's ranking of the goods and thereby, due to the linkage principle, generates higher revenues than either randomly selling the goods or selling them simultaneously.sequential auction; impression effect; linkage principle; declining price anomaly

    Testing for Collusion in Asymmetric First-Price Auctions

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    This paper proposes fully nonparametric tests to detect possible collusion in first-price procurement (auctions). The aim of the tests is to detect possible collusion before knowing whether or not bidders are colluding. Thus we do not rely on data on anti-competitive hearing, and in that sense is ’ex-ante’. We propose a two steps (model selection) procedure: First, we use a reduced form test of independence and symmetry to shortlist bidders whose bidding behavior is at-odds with competitive bidding, and Second, the recovered (latent) cost for these bidders must be higher under collusion than under competition, because collusion dwarfs competition, hence detecting collusion boils down to testing if the estimated cost distribution under collusion first order stochastically dominates that under competition. We propose rank based and Kolmogorov-Smirnov (K-S) tests. We implement the tests for Highway Procurement data in California and conclude that there is no evidence of collusion even though the reduced form test supports collusion.

    On the Inefficiency of the Uniform Price Auction

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    We present our results on Uniform Price Auctions, one of the standard sealed-bid multi-unit auction formats, for selling multiple identical units of a single good to multi-demand bidders. Contrary to the truthful and economically efficient multi-unit Vickrey auction, the Uniform Price Auction encourages strategic bidding and is socially inefficient in general. The uniform pricing rule is, however, widely popular by its appeal to the natural anticipation, that identical items should be identically priced. In this work we study equilibria of the Uniform Price Auction for bidders with (symmetric) submodular valuation functions, over the number of units that they win. We investigate pure Nash equilibria of the auction in undominated strategies; we produce a characterization of these equilibria that allows us to prove that a fraction 1-1/e of the optimum social welfare is always recovered in undominated pure Nash equilibrium -- and this bound is essentially tight. Subsequently, we study the auction under the incomplete information setting and prove a bound of 4-2/k on the economic inefficiency of (mixed) Bayes Nash equilibria that are supported by undominated strategies.Comment: Additions and Improvements upon SAGT 2012 results (and minor corrections on the previous version

    Collusion via signaling in open ascending auctions with multiple objects and complementarities

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    Collusive equilibria exist in open ascending auctions with multiple objects, if the number of bidders is sufficiently small relative to the number of objects, even with large complementarities in the buyers' utility functions. The bidders collude by dividing the objects among themselves, while keeping the prices low. Hence the complementarities are not realized

    Bidding for concessions

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    Privatization of infrastructure ventures in sectors such as energy, telecommunication, transport, and water has become popular over the last decade. Often- for good or bad reasons - private firms are given monopoly franchises under some type of long-term concession agreement, for example"Build-Operate-Transfer"schemes. The article surveys the issues arising in designing specifications as well as incentive and risk-sharing parameters comprehensively and consistently both to achieve efficient performance by the concessionaire and to minimize post-award renegotiations. Concession award should as a rule be made competitively, unless special requirements of speed, innovation, or excessive transaction cost argue otherwise. Typically, competitive concession award is made by first price sealed bids. There are strong arguments, however, to consider open auctions more seriously in a number of cases. Auctions may also be re-awarded by way of auction. However, somewhat arbitrary bid preferences may have to be set. Auctioneers for complex concession contracts should operate at arms-length from all interested parties, including politicians. It may be sensible to let independent agencies that regulate the concession scheme run the auction.Decentralization,Environmental Economics&Policies,Markets and Market Access,International Terrorism&Counterterrorism,Economic Theory&Research,International Terrorism&Counterterrorism,Environmental Economics&Policies,Access to Markets,Markets and Market Access,Economic Theory&Research

    Descending Price Optimally Coordinates Search

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    Investigating potential purchases is often a substantial investment under uncertainty. Standard market designs, such as simultaneous or English auctions, compound this with uncertainty about the price a bidder will have to pay in order to win. As a result they tend to confuse the process of search both by leading to wasteful information acquisition on goods that have already found a good purchaser and by discouraging needed investigations of objects, potentially eliminating all gains from trade. In contrast, we show that the Dutch auction preserves all of its properties from a standard setting without information costs because it guarantees, at the time of information acquisition, a price at which the good can be purchased. Calibrations to start-up acquisition and timber auctions suggest that in practice the social losses through poor search coordination in standard formats are an order of magnitude or two larger than the (negligible) inefficiencies arising from ex-ante bidder asymmetries.Comment: JEL Classification: D44, D47, D82, D83. 117 pages, of which 74 are appendi
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