Note on "Deterministic inventory lot-size models under inflation with shortages and deterioration for fluctuating demand" by Yang et al.

In a recent paper Yang et al. extended the lot-size models to allow for inflation and fluctuating demand. For this model they proved that the optimal replenishment schedule exists and is unique. They also proposed an algorithm to find the optimal policy. The present paper provides examples, which show that the optimal replenishment schedule and consequently the overall optimal policy may not exist. (C) 2002 Wiley Periodicals, Inc.