Note on a deterministic lot-size inventory model for deteriorating items with shortages and a declining market

Recently Wee [l] published an article entitled ‘A deterministic lot-size inventory model for deteriorating items with shortages and a declining market’, which appeared in volume 3 of Computers and Operations Research. In the article, Wee considers an inventory model for deteriorating items with exponentially decreasing demand rates and shortages over a finite planning horizon. An heuristic based on equal replenishment periods is suggested for both complete and partial backlogging. In early 1995 Benkherouf [2] An optimal procedure for finding the replenishment schedule for an inventory model with deteriorating and decreasing time-varying demand and shortages was suggested. The demand rate D(t) in this article is assumed to decrease over time and D(t)lD’(t) is nondecreasing with time. Although, in Benkherouf [2], shortages are permitted in the last period, the procedure suggested applies to a model with no shortages in the last period with a slight modification. In fact the procedure suggested was initially put forward in 1992 for increasing time varying demand rates functions ([3]). The aim of this short note is threefold.