ASSIGNING SLABS TO ORDERS - AN EXAMPLE OF APPROPRIATE MODEL FORMULATION

An important problem for a steel company is the assigning of slabs, i. e. semi-finished rectangular pieces of steel, to customer orders. Due to its discrete nature, the problem can be formulated as a zero-one in teger programming problem; however, real-world problems are too large (12,000-16,000 zero-one variable) to be solved exactly in a reasonable amount of computer time. In this paper we present a transportation fo rmulation for this problem that can be efficiently solved using a netw ork code of Bertsekas. Then, using rounding heuristics, the transporta tion solution can be transformed into a practical solution. An example is used to illustrate this approach. Empirical results indicate that excellent (low-cost) practical solutions can be generated for large-sc ale (300 orders and 3000 slabs) problems in less than 1 min on a 386 P C (25 MHZ).