Pareto efficiency
= Pareto efficiency
{c}
An outcome is Pareto efficient when no feasible alternative weakly improves every agent's utility and strictly improves at least one. For strict preference orders over distinct alternatives, an outcome unanimously ranked below another is inefficient. Onto <strategyproof> <social choice functions> on an unrestricted domain are Pareto efficient: rank-raising monotonicity and unanimity rule out selecting a unanimously dominated alternative.