(Q, r) inventory model with backorder discount in fuzzy demand and fuzzy ordering cost

Most of researchers assume that the annual demand and ordering cost are crisp numbers. However, there are many uncertain factors in real world. So we fuzzify the total demand and ordering cost to the triangular fuzzy numbers in a plan period, respectively. The goal of this study is to minimize the expected total annual cost with respect to order quantity, backorder price discount. Then we defuzzify by the centroid and the signed distance methods. We can find the ordering cost and the optimal order quantity by defuzzifying the total cost through the centroid method. We can do the same thing by the signed distance method. Then we compare the results obtained by these two methods.