It is easy to show that the allocation x<sub>a</sub> is Pareto-efficient: since all weights are positive, any Pareto-improvement would increase the sum, contradicting the definition of x<sub>a</sub>. | It is easy to show that the allocation x<sub>a</sub> is Pareto-efficient: since all weights are positive, any Pareto-improvement would increase the sum, contradicting the definition of x<sub>a</sub>. |