关键词: 多级库存, 延迟策略, 二层整数规划, 遗传算法, 最优解

Abstract: In this paper, a sort of optimal inventory model with postponement strategy i.e. bilevel integer programming problem was researched. Bilevel integer programming problem was proved to be equivalent to constrained integer programming problem, and could be transformed to integer programming problem without constraint via penalty function. A genetic algorithm was proposed to solve this problem. The numerical simulation results show that the proposed model can improve the inventory benefits of overall supply chain，and reasonably adjust the optimal inventory of all branch points.

Key words: multi-echelon inventory, postponement strategy, bilevel integer programming, Genetic Algorithm (GA), optimal solution