Auctioning Social Surplus: First Best Bayesian Mechanism with Ex Post Individual Rationality
2009/12/15
研討會日期 : 2009-12-15
時間 : 14:30
主講人 : 柯榮住助理教授
地點 : B110
演講者簡介 : 柯榮住教授為Ph.D. in Economics，Massachusetts Institute of Technology (2009)。現為香港中文大學經濟系助理教授。其主要研究領域為Contract Theory、Organizational Economics及Applied Econometrics。
演講摘要 : This paper constructs a concrete mechanism/auction to explore the consequence of imposing the ex post participation constraint. The main findings are:
(1) In private good cases (symmetric or asymmetric), we can obtain ex post first best, ex post budget balance, at least interim incentive compatibility and ex post individual rationality (we call it ex post social efficiency), whenever the VCG mechanism runs expected surplus. And the mechanism generating an ex post monotonic payoff is generically unique (up to an ex ante side-pay). In addition, compared with standard auctions, our mechanism generates a risk-free revenue to the seller and ex post invidually rational payoff to the bidders.
(2) In a general preference case with externality, we show there exists an ex post socially efficient mechanism when the number of participants is sufficiently small (n=2). And the choice of mechanism depends on whether the quantity is endogeneous or not.
(3) As an implication, we provide a general discussion on how divisibility, endowment distribution and preference affect the possibility of trade. For the negative result, we show a set of conditions for non-existence of the ex post socially efficient trade, such as either utility is linear or the lowest type agent's utility is independent of his endowment, which can be regarded as a stronger version of no-trade theorem (Myerson-Satterthwaite, 1983). This proposition implies non-existence of the ex post socially efficient partner dissolving mechanism. For the positive side, we provide a sufficient condition for the existence of an ex post socially efficient trade mechanism and show an explicit example.
