In this paper we investigate the convexity of the annual total cost function for the Hadley & Whitin (1963) continuous review (Q,R) inventory model with backorders and fixed lead-time, when the reorder point is non-negative and the cost per unit backordered is used to calculate the expected...

In this paper we investigate the minimization process of the exact cost function for a continuous review (Q,R) inventory model with non-negative reorder point and fixed lead-time. Backorders are allowed and the unit shortage cost is used to determine the expected annual shortage cost. Provided...