1999 Volume 11 Issue 3 Pages 512-520
In this paper, first we extend the formulation of multi-objective fuzzy scheduling problems using the ordered weighted averaging (OWA) operator. Two fuzzy scheduling problems have been already proposed: the maximization problem of the total satisfaction grade and the maximization problem of the minimum satisfaction grade. We formulate a multi-objective fuzzy scheduling problem that lies between these two problems. In our multi-objective fuzzy scheduling problem, each job is scheduled according to its own scheduling criteria. Scheduling criteria for each job are denoted by a membership function that indicates a satisfaction grade of a decision maker for the completion time of the corresponding job. Next we introduce job importance grades into the formulation of multi-objective fuzzy scheduling problems. In the previous formulation, all jobs have the same importance. There are, however, many cases where each job has different importance in the scheduling. That is, some jobs may be more important than other jobs. We propose two ways for introducing the importance grades into the formulation of multi-objective fuzzy scheduling problems. Finally we examine solutions(i.e., schedules)obtained in several formulations of multi-objective scheduling problems by computer simulations.
