In a flow-shop problem with transportation delays additionally transportation delays (time-lags between the operations) are considered which arise when a job changes from one machine to another.
If job i changes from machine Mk to Mk+1,
a job- and machine-dependent transportation delay
t ik
occurs. If these times are job-independent or
machine-independent, we write
t k
or
t i.
Constant tranportation delays are denoted by
t ik=T
and
t i
{T 1,T 2}
means that the transportation delays may take only two values.