In addition, the necessary and sufficient condition that a decision . making unit (DMU) is DEA efficient (C2GS2) and the condition that optimal solution to DEA model (C2GS2) is unique are presented under single input and single output system.

• 最后给出了单输入单输出系统下决策单元为DEA有效(C~2GS~2)的充要条件及最优解唯一的条件。