We study a problem where a group of voters must decide which candidates are elected from a set of alternatives. The voters’ preferences on the combinations of elected candidates are represented by orderings. We propose a family of restrictions of the domain of separable preferences. These...

When the members of a voting body exhibit single peaked preferences, majority winners exist. Moreover, the median(s) of the preferred alternatives of voters is (are) indeed the majority (Condorcet) winner(s). This important result of Duncan Black (1958) has been crucial in the development of...

We concentrate on the problem of the provision of one pure public good whenever agents that form the society have either single-plateaued preferences or single-peaked preferences over the set of alternatives. We are interested in comparing the relationships between different nonmanipulability...

A high court has to decide whether a law is constitutional, un- constitutional, or interpretable. The voting system is runoff. Runoff voting systems can be interpreted both, as social choice functions or as mechanisms. It is known that, for universal domains of preferences, runoff voting systems...

A group of agents has to decide whether to accept or reject a proposal. Agents vote in favor or against the proposal and, if the number of agents in favor is greater to certain quota, the proposal is accepted. The \textit{socially optimal decision} is the one adopted when all agents vote...