Abstract
The inventory control and the purchasing strategy of the enterprise are equally significant in the competitive marketplace. The optimal economic ordering quantities not only conform to the system of inventory management but also aid cost reduction while placing an order for items. In order to choose cooperated suppliers and buy appropriate amounts of goods, this thesis combines these two issues to construct the multi-item multi-supplier inventory models by the approach of mathematic programming simultaneously considering shortages, price discounting, production limits of suppliers and financial restrictions of ventures. Accordingly we solve the problems via the independent cycle approach and the fixed cycle approach respectively. In addition, the impact of variable discount rates provided by different suppliers with no shortages allowed is presented in this thesis as well.By way of coding computer programs, from the output data of experiments with shortages we show that choosing those suppliers that offer cheapest prices and optimal production quantities can eventually result in the lowest inventory system cost. In most of the cases, the computational outcomes show that the fixed cycle approach is more cost-effective. Therefore, using the fixed cycle approach to settle procurement problems in shortage allowed is suggested. On the other hand, in no shortage allowed the effect of suppliers providing varied price discounting is obviously greater when there are more vendors. Consequently, decision managers should think it over that whether various price discounting would bring benefits to the company or not.