A comment on “Supply chain DEA: production possibility set and performance evaluation model

In a recent paper in this journal, Yang et al. [Feng Yang, Dexiang Wu,Liang Liang, Gongbing Bi & Desheng Dash Wu (۲۰۰۹), supply chainDEA:production possibility set and performance evaluation model] definedtwo types of supply chain production possibility set which were proved to beequivalent to each other. They also proposed a new model for evaluatingsupply chains. There are, however, some shortcomings in their paper. In thecurrent paper, we correct the model, the theorems, and their proofs.