Three unequal period inventory models with cost changes

There have been extensive discussions in the literature for possible extension of the basic economic order quantity (EOQ) model under various situations where the original assumptions are slack. This paper is concerned with three unequal period inventory models with cost increases, which has not been adequately addressed yet. We provide four possible types of the structure of the optimal policy and develop short procedures for determining optimal ordering policy. Our method developed in this paper provides a way to investigate the classical EOQ model for possible extension.