Locating public facilities by majority: Stability, consistency and group formation

We consider the following allocation problem: A Þxed number of public facilities must be located on a line. Society is composed of N agents, who must be allocated to one and only one of these facilities. Agents have single peaked preferences over the possible location of the facilities they are assigned to, and do not care about the location of the rest of facilities. There is no congestion. We show that there exist social choice correspondences that choose locations and assign agents to them in such a way that: (1) these decisions are Condorcet winners whenever one exists, (2) the majority of the users of each facility supports the choice of its location, and (3) no agent wishes to become a user of another facility, even if that could induce a change of its present location by majority voting.