SCHEPLAV - a scheduling expert for steel-making process

Scheplan is an expert system kernel that was developed for scheduling steel-making processes. The typical constraints in such processes are a fixed sequence of production stages, no machine conflicts among products, low waiting time, continuous use of some machines, and a resting time requirement for some machines. The approach presented to making a schedule that satisfies the constraints is not to obtain an optimal solution, but rather to obtain a feasible solution efficiently. The reason for this is that it is very difficult to define an evaluation function for the optimum, and that a combinatorial explosion may prevent a schedule method is introduced, in which the system efficiently generates a candidate schedule by a subscheduling and merging method, and the user evaluates and modifies the candidate schedule by interactive refinement.