Fuzzy Bi-level Decision-Making Techniques: A Survey <s> Planning and scheduling operations <s> This paper presents a fuzzy bilevel programming approach to solve the flow shop scheduling problem. The problem considered here differs from the standard form in that operators are assigned to the machines and imposing a hierarchy of two decision makers with fuzzy processing times. The shop owner considered higher level and assigns the jobs to the machines in order to minimize the flow time while the customer is the lower level and decides on a job schedule in order to minimize the makespan. In this paper, we use the concepts of tolerance membership function at each level to define a fuzzy decision model for generating optimal (satisfactory) solution for bilevel flow shop scheduling problem. A solution algorithm for solving this problem is given. Copyright Springer-Verlag Berlin/Heidelberg 2005 <s> BIB001 </s> Fuzzy Bi-level Decision-Making Techniques: A Survey <s> Planning and scheduling operations <s> This paper studies scheduling of inbound trucks at the inbound doors of a cross-dock facility under truck arrival time uncertainty. Arrival time of an inbound truck is considered to be unknown. In particular, the cross-dock operator only acknowledges the arrival time window of each truck, i.e., the lower and upper bounds of any inbound truck's arrival time. In absence of any additional information, the cross-dock operator may use three approaches to determine a scheduling strategy: deterministic approach (which assumes expected truck arrival times are equal to their mid-arrival time windows), pessimistic approach (which assumes the worst truck arrivals will be realized), and optimistic approach (which assumes the best truck arrivals will be realized). In this paper, a bi-level optimization problem is formulated for pessimistic and optimistic approaches. We discuss a Genetic Algorithm (GA) to solve the truck-to-door assignments for given truck arrival times, which solves the deterministic approach. Then the GA is modified to solve the bi-level formulations of the pessimistic and the optimistic approaches. Our numerical studies show that an hybrid approach regarding the pessimistic and the optimistic approaches may outperform all of the three approaches in certain cases. <s> BIB002
For planning and scheduling operations in a decentralized manner, Abass BIB001 presented a fuzzy bilevel programming approach to solve a flow shop scheduling problem with fuzzy processing times in a hierarchy of two decision entities, in which the shop owner at the higher level assigns jobs to machines in order to minimize the flow time, while the customer at the lower level decides on a job schedule in order to minimize the makespan. Konur and Golias BIB002 studied scheduling of inbound trucks at inbound doors of a cross-dock facility under truck arrival time uncertainty. The authors formulated this problem as pessimistic and optimistic bi-level decision problems respectively in which the uncertain truck arrival time is handled by fuzzy number with a triangular distribution. Also, the authors developed a genetic algorithm to solve the bilevel pessimistic and optimistic formulations.