In a recent paper Gutiérrez et al. (2008) show that the lot-sizing problem with inventory bounds can be solved in O(T log T) time. In this note we show that their algorithm does not lead to an optimal solution in general.

The most recent optimization algorithm for (s, S) order policies with continuous demand was developed byFedergruen and Zipkin (1985). This was also the first efficient algorithm, which uses policy iteration instead ofdiscretization. Zheng and Federgruen (1991) developed an even more efficient...