Optimal Grain Carryovers in Open Economies: A Graphical Analysis
用动态规划图形分析开放经济下谷物最优储存、贸易和借贷政策，发现结转量随供给增加而上升、随世界价格上升而下降，净进口则随两者上升而下降，且谷物储备与外汇借贷互为替代与补充。
Abstract Optimal storage, trade, and borrowing policies for grain are analyzed graphically using dynamic programming. World prices and domestic harvests are assumed to be stochastic. Optimal carryovers are generally increasing in supply and decreasing in world prices, while net imports are decreasing in both supply and world prices. Optimal levels of carryovers and net imports are influenced by the opportunity to borrow and save foreign exchange. It is shown that grain reserves and foreign exchange borrowing/saving are alternative inventory systems which both complement and substitute for one another.