Determining assurance interval for non-Archimedean element in the improving outputs model in DEA

Recently Jahanshahloo and Khodabakhshi [Appl. Math. Comput., in press] in an article, "suitable combination of inputs for improving outputs in DEA with determining inputs congestion", presented a model in which some inputs can be increased on the contrary of existing models in DEA. It is important to determine the value or interval of non-Archimedean c such that envelopment form is bounded, in other words multiplier form is feasible. In this article in addition to determining assurance interval of 8 for boundedness of the envelopment model, the feasibility of the multiplier model, we also provide an alternative proof for unboundedness. An illustrative example is exhibited, too. (C) 2003 Elsevier Inc. All rights reserved.