Heuristic algorithms for job‐shop scheduling problemswith stochastic precedence constraints

This paper deals with job‐shop scheduling with stochastic precedenceconstraints given by so‐called OR networks. At first, a job‐shop problem withstochastic OR network precedence constraints is described, where the expected makespan isto be minimized. Next, the concept of an aggregate schedule is discussed, which represents a deterministic staticscheduling policy for our stochastic problem. The construction of an appropriate aggregatedisjunctive graph permits us to adapt the shifting bottleneck heuristic. After that,a priority‐rulemethod is proposed for finding an approximate aggregate schedule. An experimentalperformance analysis shows that both heuristics provide good approximate solutions. Finally,we briefly discuss a flow‐shop problem with OR network precedence constraints and thecase of cyclic OR networks.