although the other costs are not

although the other costs are not. Several researchers have studied the effect of delayed payments on the EOQ.
Goyal 1 was the first to develop a model for a delay in payment to the supplier, making all the usual assumptions of the classic EOQ
model except for when payment is due. Aggarwal and Jaggi 2 developed an ordering policy for deteriorating items. Shinn et al. 3
proposed a model to simultaneously determine the retailer’s optimal price and lot size. Hwang and Shinn 4 dealt with pricing and
lot-sizing decisions for exponentially deteriorating products. Liao et al. 5 studied an inventory model with an initial-stock-dependent
consumption rate. They assumed shortages are not allowed and the effects of inflation, deterioration, and the initial-stock-dependent
consumption rates are discussed. Sarker et al. 6 developed a model to determine an optimal ordering policy for deteriorating items
under inflation and fully backordered shortages. Chang and Dye 7 developed a model for the optimal ordering policy for deteriorating
items when partial backordering is assumed. In all this research two common cases are considered; the delayed payment is due before
the inventory is exhausted or after the inventory level reaches to zero.