Fairness and partial coercion in land assembly Abstract   A holdout problem arises in a land assembly environment in which one buyer is interested in a large landmass characterized by fragmented ownership among many landowners. A simple holdoutresolving mechanism is obtained that asymptotically (as the number of landowners increase) solves a mechanism design problem with two novel criteria. One, a partial coercion constraint that respects property rights only in an u0027aggregateu0027 sense; and two, a fairness constraint that requires the terms of trade (per unit area) to be the same for every landowner. The mechanism is budgetbalanced, semianonymous, weakly strategyproof and noncoercive for the buyer while also being strategyproof in the large for landowners.

BulowKlempererStyle Results for Welfare Maximization in TwoSided Markets We consider the problem of welfare maximization in twosided markets using simple mechanisms that are priorindependent. The seminal impossibility result of Myerson and Satterthwaite 1983 shows that even for bilateral trade, there is no feasible (IR, truthful and budget balanced) mechanism that has welfare as high as the optimalyetinfeasible VCG mechanism, which attains maximal welfare but runs a deficit. On the other hand, the optimal feasible mechanism needs to be carefully tailored to the Bayesian prior, and is extremely complex, eluding a precise description. In this paper we present BulowKlempererstyle results to circumvent these hurdles in doubleauction market settings. We suggest using the Buyer Trade Reduction (BTR) mechanism, a variant of McAfeeu0027s mechanism, that is feasible and simple (in particular, it is deterministic, priorindependent, and anonymous). First, in the setting where the buyersu0027 and sellersu0027 values are sampled i.i.d. from the same distribution, we show that for any such market of any size, BTR with one additional buyer whose value is sampled from the same distribution has expected welfare at least as high as the optimal in the original market. We then move to a more general setting where the buyersu0027 values are sampled from one distribution, and the sellersu0027 from another, focusing on the case where the buyersu0027 distribution firstorder stochastically dominates the sellersu0027 distribution. We present bounds on the number of buyers that, when added, cause BTR in the augmented market to achieve welfare at least as high as the optimal in the original market. Our lower bounds extend to a large class of mechanisms. In addition, we present positive results about the usefulness of pricing at a sample for welfare maximization in twosided markets under the above two settings, which to the best of our knowledge are the first sampling results in this context.