  We consider an auction design problem where a seller sells multiple
homogeneous items to a set of connected buyers. Each buyer only knows the
buyers she directly connects with and has a diminishing marginal utility
valuation for the items. The seller initially only connects to some buyers who
can be directly invited to the sale by the seller. Our goal is to design an
auction to incentivize the buyers who are aware of the auction to further
invite their neighbors to join the auction. This is challenging because the
buyers are competing for the items and they would not invite each other by
default. Thus, rewards need to be given to buyers who diffuse information, but
the rewards should be carefully designed to guarantee both invitation
incentives and the seller's revenue. Solutions have been proposed recently for
the settings where each buyer requires at most one unit and demonstrated the
difficulties of the design. We move this forward to propose the very first
diffusion auction for the multi-unit demand settings to improve both the social
welfare and the seller's revenue.
