In operations research, Johnson's rule is a method of scheduling jobs in two work centers.
It also reduces the amount of idle time between the two work centers.
The method minimizes the makespan in the case of two work centers.
Furthermore, the method finds the shortest makespan in the case of three work centers if additional constraints are met.
[1] The technique requires several preconditions: Johnson's rule is as follows: Given significant idle time at the second work center (from waiting for the job to be finished at the first work center), job splitting may be used.