ranking dmus in dea by using fuzzy logical

In data envelopment analysis (dea) models many decision making units (dmus) are classified as efficient and some methods for ranking both efficient and inefficient dmus have been proposed. cross-efficiency method is one of them. in cross-efficiency ranking methods, in addition efficiency value all units, also selection of weights are important. in this paper, the weights of the cross-evaluation determined by logical fuzzy, such as it is proportional with efficiencies. therefore, it basically differs from previous methods.