  In this paper we consider the open shop scheduling problem where the jobs
have delivery times. The minimization criterion is the maximum lateness of the
jobs. This problem is known to be NP-hard, even restricted to only 2 machines.
We establish that any list scheduling algorithm has a performance ratio of 2.
For a fixed number of machines, we design a polynomial time approximation
scheme (PTAS) which represents the best possible result due to the strong
NP-hardness of the problem.
