Mohammadreza Alirezaee - School of Mathematics, Iran University of Sciences and Technology, Tehran, Iran.

Computationally, selection of a proper numerical value for infinitesimal non Archimedean epsilon in DEA models has some difficulties. Although there are several algorithms for selecting the proper non-Archimedean epsilon, it is important to introducemethods in order to calculate the efficiency of DMUs without using epsilon. One of these methods is a two-phase method, which obtains the efficiency of each DMUthrough solving two LPs, which the second LP is depended to the first. This paper proposes a method, which is able to compute the efficiency of DMUs by two LPs, which are not depended to each other and computationally can solve in a parallelcomputation. The major of this method is to find two references for each unit and combine them to obtain actual reference.

Data Envelopment Analysis (DEA); Decision Making Units (DMUs); Non-Archimedean; Two-phase method; Reference point