Two-machine open shop scheduling with special transportation times

The paper considers a problem of scheduling n jobs in a two-machine open sh op to minimise the makespan, provided that preemption is not allowed and th e interstage transportation times are involved. In general, this problem is known to be NP-hard. We present a linear time algorithm that finds an opti mal schedule if no transportation time exceeds the smallest: of the process ing times. We also describe an algorithm that creates a heuristic solution to the problem with job-independent transportation times. Our algorithm pro vides a worst-case performance ratio of 8/5 if the transportation time of a job depends on the assigned processing route. The ratio reduces to 3/2 if all transportation times are equal.