A Subsidized Vickrey Auction for Cost Sharing

We introduce a subsidized Vickrey auction for cost sharing problems. Although the average, marginal, and serial cost sharing mechanisms are budget-balanced, they are not allocatively efficient and they do not induce players to truthfully reveal their values as a dominant strategy. The conventional Vickrey auction, on the other hand, is allocatively efficient and does induce truthful bidding as a dominant strategy, but also generates an overpayment. This paper modifies the conventional Vickrey auction so that some of the overpayment is used to subsidize additional production without upsetting the players' incentives to bid truthfully. Although this subsidized Vickrey auction is not allocatively efficient, it always Pareto dominates the conventional Vickrey auction and sometimes dominates other existing cost sharing mechanisms.