Minimising makespan in the two-machine flow-shop with release times

Abstract

This paper considers the two-machine flow-shop problem with the objective of minimising the makespan subject to different release times. In view of the strongly NP-hard nature of this problem, five lower bounds and two new dominance criteria are proposed together with a decomposition procedure that reduces the problem size by setting jobs at the beginning of the sequence. Several branch and bound procedures are described by applying different lower bounds and branching schemes. A detailed computational campaign has been performed on different kinds of instances testing problems with size up to 200 jobs.

Keywords:

• branch and bound
• flow-shop scheduling
• release times