Multi-unit Auction over a Social Network

Diffusion auction is an emerging business model where a seller aims to incentivise buyers in a social network to diffuse the auction information thereby attracting potential buyers. We focus on designing mechanisms for multi-unit diffusion auctions. Despite several attempts at this problem, existing mechanisms are unsatisfactory in one way or another. Here, we propose two new mechanisms for multi-unit diffusion auction: (1) MUDAN which satisfies IC and a weakened form of efficiency, and (2) MUDAR which satisfies efficiency and a weakened form of IC. We define the mechanisms for the bottleneck case of the problem, namely when each buyer demands a single item, to which the more general multi-demand setting can be reduced. Our mechanisms are the first multi-unit diffusion auctions that satisfy a range of desirable properties that include truthfulness and efficiency conditions. This closes the gap left open by the previous work.