  We consider a truthful facility location problem in which there is a set of
agents with private locations on the line of real numbers, and the goal is to
place a number of facilities at different locations chosen from the set of
those reported by the agents. Given a feasible solution, each agent suffers an
individual cost that is either its total distance to all facilities
(sum-variant) or its distance to the farthest facility (max-variant). For both
variants, we show tight bounds on the approximation ratio of strategyproof
mechanisms in terms of the social cost, the total individual cost of the
agents.
