Single-machine scheduling to minimize the total earliness and tardiness is strongly NP-hard

This paper revisits the classic single-machine scheduling to minimize the total earliness and tardiness. It is known that the problem is NP-hard in the ordinary sense, but the exact complexity of the problem is long-standing open. We show in this paper that this problem is strongly NP-hard. (C) 2013 Published by Elsevier B.V.