Genetic algorithms are a very popular heuristic which have been successfully applied to many optimization problems within the last 30 years. In this chapter, we give a survey on some genetic algorithms for shop scheduling problems. In a shop scheduling problem, a set of jobs has to be processed on a set of machines such that a specific optimization criterion is satisfied. According to the restr...

We investigate the multiprocessor multi stage open shop scheduling problem In this variant of the open shop model there are s stages each consisting of a number of parallel identical machines Each job consists of s operations one for each stage that can be executed in any order The goal is to nd a non preemptive schedule that minimizes the makespan We derive two approximation results for this N...

In this paper we consider a generalized version of the classical preemptive open shop problem with sum of weighted job completion times objective. The main result is a (2 + ε)-approximation algorithm for this problem. In the last section we also discuss the possibility of improving our algorithm.