A note of correction on ‘Multi-product scheduling on a single machine’

The economic lot scheduling problem is the problem of scheduling the production of several items in a single facility so that demands are met without stockouts or backorders and the long run average inventory carrying and setup costs are minimized. Mallya developed a scheme to schedule without the determination of the cost factors. He also provided a method to compute a lower bound using economic batch quantity (EBQ). However, the paper shows that significant improvements on his approach can be achieved. First, it shows how to find an optimal cycle time under his approach without enumeration. Second, the paper provides a tighter lower bound than he used by computing EBQs under a constraint on the capacity of the machine. Finally, it gives clarifying explanations on and relationships between the optimal total daily cost, lower bounds and upper bounds.