Complexity results for flow-shop problems with a single server

Flow-shop problems with a single server are generalizations of classical flow-shop problems. Immediately before processing, each operation must be loaded onto the corresponding machine, which takes a certain setup time. These setup times are assumed to be separable from the processing times, i.e. a setup on a subsequent machine may be performed while the job is still processed on the preceding machine. All setups have to be done by a single server which can perform at most one setup at a time. New complexity results are derived for special cases.