Special Case of the Single-Machine Total Tardiness Problem is NP-hard

this paper we show that the special case B-1 of the single machine
total tardiness problem 1||\sum T_j is NP-hard in ordinary sense. For the
case there exist pseudo-polynomial algorithm O(n \sum p_j) time.

A.A. Lazarev, E.R. Gafarov (2006), Special Case of the Single-Machine Total Tardiness Problem is NP-hard. Journal of Computer and Systems Sciences International, 45 (3), 450-458. (journal impact factor 2018: 0.513). Q3