On optimal two-stage lot sizing and inventory batching policies

A recent paper considered the two-stage lot-sizing problem with finite production rates at both stages. The problem was classified according to: whether the production rate at the first stage is greater or less than that at the second stage, whether the production batch size at the first stage is greater or less than that at the second stage and whether the transfer from the first stage to the second stage is continuous or in batches. The objective of this note is to offer an alternative (more direct and intuitive) way to derive and present essentially similar results and also to extend the analysis by relaxing one of the assumptions.