Sequencing with chain structured precedence constraints and minimal and maximal separation times

Considers a single machine scheduling problem which has been solved for a medical laboratory. In this problem, there are not only chain structured precedence constraints, but also minimal and maximal times separating successive jobs in a same chain. The criterion to be minimized is the makespan. This problem arises particularly in systems where chemical processes are involved. In these systems, jobs are transportation operations and chemical processes can be modeled as chains. Therefore the problem studied in this paper is of practical importance. The authors first state that the problem is NP-complete. As a consequence, the authors propose heuristics for large size problems and a branch and bound algorithm for small size problems. Computational results are reported