Combinatorial auctions are now an important e-commerce application where bidders can bid on combination of items. The problem of selecting the best bids that cover all items, i.e., the winner determination problem (WDP), is NP-hard. The time constrained variant of this problem, considered in this paper, is the bid evaluation problem where temporal windows and precedence constraints are associat...

We propose a service-oriented combinatorial auction mechanism in an uncertain context where a shipper needs to outsource its transport operations to external carriers. Uncertainty is on shipper demand, carrier capacity and carrier lead time. A two-stage stochastic formulation is proposed to model the winner determination problem. A Monte Carlo approach combined with the sample average approxima...

Although recent years have seen a surge of interest in the computational aspects of social choice, no attention has previously been devoted to elections with multiple winners, e.g., elections of an assembly or committee. In this paper, we fully characterize the worst-case complexity of manipulation and control in the context of four prominent multi-winner voting systems. Additionally, we show t...

Combinatorial auctions, that is, auctions where bidders can bid on combinations of items, tend to lead to more efficient allocations than traditional auction mechanisms in multi-item auctions where the agents’ valuations of the items are not additive. However, determining the winners so as to maximize revenue is NP-complete. First, we analyze existing approaches for tackling this problem: exhau...

We consider the problem of rational, self-interested, economic agents who must negotiate with each other in order to carry out their plans. Customer agents express their plans in the form of task networks with temporal and precedence constraints. The market runs a combinatorial reverse auction, in which supplier agents submit bids specifying prices for combinations of tasks, along with time win...

We introduce the (j, k)-Kemeny rule – a generalization of Kemeny’s voting rule that aggregates j-chotomous weak orders into a k-chotomous weak order. Special cases of (j, k)Kemeny include approval voting, the mean rule and Borda mean rule, as well as the Borda count and plurality voting. Why, then, is the winner problem computationally tractable for each of these other rules, but intractable fo...