Inventory models involving discrete decision variables: A discussion

This study discusses existing researches that presented solution procedures to optimize discrete decision variables in various inventory models. To gain more insights into the solution procedures and their results, we first review the classical inventory theories and show their connections and applications to current researches. Then, we demonstrate the influence of necessary conditions to the optimal integer solutions, and then clarify some arguments appeared in the supply chain inventory models, where similar conditions are applied to derive the closed-form solution for the integer multiplier.