Inventory Service-Level Measures: Convexity and Approximation
指出两种常用库存服务水平度量的标准近似在许多情况下表现不佳，并证实了这些度量的精确公式是控制变量的凸函数，建议在实际工作中认真考虑精确表达式。
We argue that standard approximations for two often-used inventory service-level measures may perform poorly in many situations. Then we confirm the long-standing conjecture that the (relatively) exact formulas for these quantities are convex functions of the relevant control variables. Both results suggest the exact expressions should be seriously considered in practical work.