Abstract:

With the introduction of proper partial order relation into the data envelopment analysis （DEA） method based on the partial ordered set theory, not only the relationships between different decision making units are established, but also some reasons which make the decision making units inefficient or weakly efficient are known. However, less information will be proposed for decision makers with the increase of the index number of input and output data which makes the relationships between different decision making units decrease. With the introduction of meet and join operations of decision making units, new sample decision making units are provided and the original decision making units and the provided sample decision making units compose a lattices. The lattice relation of decision making units not only proposes a new projection method but also a cooperation and competition method for decision makers. Some related theorems, algorithms and examples are provided.