Abstract

In most real-world (electronic) marketplaces, there are other considerations besides maximizing immediate economic value. We present a sound way of taking such considerations into account via side constraints and non-price attributes. Side constraints have a significant impact on the complexity of market clearing. Budget constraints, a limit on the number of winners, and XOR-constraints make even noncombinatorial markets-complete to clear. The latter two make markets-complete to clear even if bids can be accepted partially. This is surprising since, as we show, even combinatorial markets with a host of very similar side constraints can be cleared in polytime. An extreme equality constraint makes combinatorial markets polytime clearable even if bids have to be accepted entirely or not at all. Finally, we present a way to take into account additional attributes using a bid re-weighting scheme, and prove that it does not change the complexity of clearing. All of the results hold for auctions as well as exchanges, with and without free disposal. 1

Citations