Uet-scheduling with Chain-type Precedence Constraints Uet|scheduling with Chain-type Precedence Constraints

x{ Scope and Purpose. | We consider a scheduling problem in a two-processor system where (i) every job can be processed on only one machine and where (ii) there are chain-type precedence relations among the jobs. The goal is to minimize the makespan. This continues the work of Chang and Lee 1], Jansen 4] and of Kellerer and Woeginger 5]. Abstract. | We consider a special case of the precedence constrained scheduling problem of n unit execution time jobs on two parallel machines without preemption: The precedence constraints are chain-type, and each job can be processed on only one of the two machines. We show that this problem is NP-complete in general, and we derive an approximation algorithm with constant worst case guarantee.