Open Access
Strategy-proof location of public facilities
(Elsevier, 2018) Alcalde Unzu, Jorge; Vorsatz, Marc; Economía; Ekonomia
Consider the problem of locating a public facility taking into account the agents' preferences. To construct strategy-proof social choice rules, we propose a new preference domain that allows agents to have any single-peaked or any single-dipped preference on the location of the facility such that the peak/dip of the preference is in her own location. We characterize all strategy-proof rules in this general framework and study the conditions under which this family of strategy-proof rules includes non-dictatorial rules that have more than two alternatives in the range or that are Pareto efficient. Finally, we characterize for some focal cases all strategy-proof and Pareto efficient rules.
Open Access
Non anonymous ballot aggregation: an axiomatic generalization of Approval Voting
(2011) Alcalde Unzu, Jorge; Vorsatz, Marc; Economía; Ekonomia
We study axiomatically situations in which the society agrees to treat voters with different characteristics distinctly. In this setting, we propose a set of six intuitive axioms and show that they jointly characterize a new class of voting procedures, called Personalized Approval Voting. According to this family, each voter has a strictly positive and finite weight (the weight is necessarily the same for all voters with the same characteristics) and the alternative with the highest number of weighted votes is elected. Hence, the implemented voting procedure reduces to Approval Voting in case all voters are identical or the procedure assigns the same weight to all types.
Open Access
Measuring the cohesiveness of preferences: an axiomatic analysis
(Springer Berlin Heidelberg, 2013) Alcalde Unzu, Jorge; Vorsatz, Marc; Economía; Ekonomia
In this paper, we axiomatically study how to measure the similarity of preferences in a group of individuals. For simplicity, we refer to this as the cohesiveness. First, we provide axioms that characterize a family of linear and additive measures whose intersection is a partial ordinal criterion similar to first order stochastic dominance. The introduction of some additional properties isolates a one-parameter subfamily. This parameter evaluates the effect on the cohesiveness if one individual changes his ranking on a single pair of objects, as a function of how many of the remaining individuals in the group rank the first object over the second and vice versa. Finally, we characterize the focal measures of this subfamily separately showing that they coincide with measures constructed using two, at first sight, totally different approaches suggested in the literature.
Open Access
Size approval voting
(2007) Alcalde Unzu, Jorge; Vorsatz, Marc; Economía; Ekonomia
We propose a new class of voting rules, called Size Approval Voting. According to this rule, the effective weight of a vote from a given individual depends on how many other alternatives the very same individual votes for. In particular, weights are assumed to be non-negative and weakly decreasing in the number of approved alternatives. Then, for a given profile of individual votes, all those alternatives with the maximal sum of weighted votes are elected. We show in our axiomatic analysis that the family of all Size Approval Voting is characterized by a set of natural properties.
Open Access
Strategy-proof location of public facilities
(2015) Alcalde Unzu, Jorge; Vorsatz, Marc; Economía; Ekonomia
Agents frequently have different opinions on where to locate a public facility. While some agents consider the facility a good and prefer to have it nearby, others dislike it and would like to see it built far away from their own locations. To aggregate agents' preferences in these situations, we propose a new preference domain according to which each agent is allowed to have single-peaked or single-dipped preferences on the location of the facility, but in such a way that the peak or dip is situated in her own location. We characterize all strategy-proof rules in this general framework and show that they are also group strategy-proof. Finally, we characterize for some focal cases the rules that additionally satisfy Pareto efficiency.
Open Access
Non-anonymous ballot aggregation: an axiomatic generalization of Approval Voting
(Elsevier, 2013) Alcalde Unzu, Jorge; Vorsatz, Marc; Economía; Ekonomia
We study axiomatically situations in which the society agrees to treat voters with different characteristics distinctly. In this setting, we propose a set of intuitive axioms and show that they jointly characterize a new class of voting procedures, called Type-weighted Approval Voting. According to this family, each voter has a strictly positive and finite weight (the weight is necessarily the same for all voters with the same characteristics) and the alternative with the highest number of weighted votes is elected. The implemented voting procedure reduces to Approval Voting in case all voters are identical or the procedure assigns the same weight to all types. Using this idea, we also obtain a new characterization of Approval Voting.