R O M a a Branch and Bound Algorithm for the Minimum Storage-time Sequencing Problem

The minimum storage-time sequencing problem generalizes many well known problems 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 e cently. To improve upon this lower bound, we employ a bundle optimization 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 rst Chv atal closure equals the convex hull of all the integer solutions of the problem. 2