Weighted committee games generalize n-player simple voting games to m ≥ 3 alternatives. The committee’s aggregation rule treats votes anonymously but parties, shareholders, members of supranational organizations, etc. differ in their numbers of votes. Infinitely many vote distributions induce only finitely many distinct mappings from preference profiles to winners, i.e., non-equivalent committe...

An important issue for economics and the decision sciences is to understand why allocation and decision procedures are plagued by manipulative and paradoxical behavior once there are n ≥ 3 alternatives. Valuable insight is obtained by exploiting the relative simplicity of the widely used Copeland method (CM). By use of a geometric approach, we characterize all CM manipulation, monotonicity, con...

The problems of controlling an election have been shown NP-complete in general but polynomial-time solvable in single-peaked elections for many voting correspondences. To explore the complexity border, we consider these control problems by adding/deleting votes in elections with bounded single-peaked width k. Single-peaked elections have singlepeaked width k = 1. We prove that the constructive ...

In a party-based election, the voters are grouped into parties and all voters of a party are assumed to vote according to the party preferences over the candidates. Hence, once the party preferences are declared the outcome of the election can be predicted. However, in the actual election, the members of some “instable" parties often leave their own parties to join other parties. We introduce t...