A branch and bound algorithm for the Minimum Storage-Time Sequencing problem

The minimum storage-time sequencing problem generalizes many well-known prob- lems in combinatorial optimization, such as the directed linear arrangement and the problem of minimizing the weighted sum of completion times, subject to precedence constraints on a single processor. In this paper we propose a new lower bound, based on a Lagrangian relaxation, which can be computed very efficiently. To improve upon this lower bound, we employ a bundle op- timization algorithm. We also show that the best bound obtainable by this approach equals the one obtainable from the linear relaxation computed on a formulation whose first Chvatal closure equals the convex hull of all the integer solutions of the problem.