Abstract: Auctions for digital goods are auctions where the auctioneer has an unlimited supply of a single commodity. In this auction framework, we consider a bidder model where each participant has a probability p of joining a collective colluding group. We show that any auction that is B-competitive without colluders, is B/(1-p)2-competitive in the presence of colluders no matter the colluding strategy.
This is joint work with Sandy Irani, Gwendoline Shu-Hsien Chien, and Matthew Nguyen.