A new model for the preemptive earliness-tardiness scheduling problem
Computers and Operations Research
An exact algorithm for single-machine scheduling without machine idle time
Journal of Scheduling
Computers and Operations Research
Solving the single-machine sequencing problem using integer programming
Computers and Industrial Engineering
Iterated local search and very large neighborhoods for the parallel-machines total tardiness problem
Computers and Operations Research
Computers and Operations Research
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New observations are made about two lower bound schemes for single-machine min-sum scheduling problems. We find that the strongest bound of those provided by transportation problem relaxations can be computed by solving a linear program. We show the equivalence of this strongest bound and the bound provided by the LP relaxation of the time-indexed integer programming formulation. These observations lead to a new lower bound scheme that yields fast approximation of the time-indexed bound. Several techniques are developed to facilitate the effective use of the new lower bound in branch-and-bound. Numerical experiments are conducted on 375 benchmark problems of the total weighted tardiness problem from OR-Library. Results obtained with our new method are spectacular; we are able to solve all 125 open problems to optimality.