A note on a well-known dispatching rule to minimize total tardiness

The single machine tardiness problem is considered. We clarify and correct an earlier result related to the Modified Due Date (MDD) Rule of Baker and Bertrand and show that a heuristic does not always satisfy an optimal sequence. However, we present some interesting special cases of optimal sequences that do satisfy the MDD Rule. We believe this note is important because the MDD Rule is still considered to be one of the most efficient rules to minimize the single machine tardiness problem. Because of its dispatching nature and simplicity, the MDD Rule is found to be very practical. It is widely applied in both static and dynamic job shop and industrial settings where setup times if any are negligible or included in the job processing times and hence not an issue.