on efficiency of the English auction

We study efficiency properties of the irrevocable exit English auction in a setting with interdependent values. Maskin (1992) shows that the pairwise single-crossing condition is both necessary and sufficient for efficiency of the English auction with two bidders. This paper extends both Maskin's result and the single-crossing condition to the case of N bidders. We introduce the generalized single crossing - a fairly intuitive extension of the pairwise singlecrossing - and show that it is both a necessary and sufficient condition for the existence of an efficient equilibrium in the N-bidder English auction. Keywords: English auction, efficient auction, ex post equilibrium, single-crossing, interdependent values. JEL Classifications: D44, C72, C73.