The bi-objective winner determination problem (2WDP-SC) of a combinatorial procurement auction for transport contracts is characterized by a set B of bundle bids, with each bundle bid b ∈ B consisting of a bidding carrier cb, a bid price pb, and a set τb of transport contracts which is a subset of the set T of tendered transport contracts. Additionally, the transport quality qt,cb is given whic...

Judgment aggregation is a collective decision making framework where the opinions of a group of agents is combined into a collective opinion. This can be done using many different judgment aggregation procedures. We study the computational complexity of computing the group opinion for several of the most prominent judgment aggregation procedures. In particular, we show that the complexity of th...

This paper introduces a bi-objective winner determination problem which arises in the procurement of transportation contracts via combinatorial auctions. The problem is modelled as an extension to the set covering problem and considers the minimisation of the total procurement costs and the maximisation of the service-quality level of the execution of all transportation contracts tendered. To s...

The subject of this thesis is the study of computational aspects of approval voting. Mostof the works are theoretical results about computational issues raised by approval voting, in manydi erent settings. Indeed, I use algorithmic techniques like polynomial reductions to prove that manyproblems are di cult to solve in the context of approval voting. However, I also study some quest...

We propose a dedicated tabu search algorithm (TSX_WDP) for the winner determination problem (WDP) in combinatorial auctions. TSX_WDP integrates two complementary neighborhoods designed respectively for intensification and diversification. To escape deep local optima, TSX_WDP employs a backbone-based recombination operator to generate new starting points for tabu search and to displace the searc...

In this paper we address the problem of picking a subset of bids in a general combinatorial auction so as to maximize the overall profit using the first-price model. This winner determination problem assumes that a single bidding round is held to determine both the winners and prices to be paid. We introduce six variants of biased random-key genetic algorithms for this problem. Three of them us...

Combinatorial auctions are widely used for the procurement of transportation services. In these auctions, shippers act as auctioneers who need to outsource a number of transportation services to external carriers. Carriers compete by submitting bids on packages of shippers' requests. After receiving all carriers' bids, the shipper solves the well-known winner determination problem (WDP) in orde...

This paper introduces a bi-objective winner-determination problem and presents a multiobjective genetic algorithm to solve it. The problem examined arises in the procurement of transportation contracts via combinatorial auctions. It is modeled as an extension to the set-covering problem and considers the minimization of the total procurement costs and the maximization of the service-quality lev...

The POSSIBLE WINNER problem asks whether some distinguished candidate may become the winner of an election when the given incomplete votes (partial orders) are extended into complete ones (linear orders) in a favorable way. Under the k-approval protocol, for every voter, the best k candidates of his or her preference order get one point. A candidate with maximum total number of points wins. The...

Combinatorial auctions (CAs) where bidders can bid on combinations of items is an important model in many application areas. CAs attract more and more attention in recent years due to its relevance to fast growing electronic business applications. In this paper, we study the winner determination problem (WDP) in CAs which is known to be NP-hard and thus computationally difficult in the general ...