the trim line at PW is a small sub assembly line that, line that along with other such lines, feeds into the final chassis line the entire assembly of line, which consists of more than 900 workstations, is to make PW's new W cars. The trim line itself involves only 13 work elements and must handle 20 cars per hour. In addition to the usual precedence constraints, there are two zoning constraints. First, work elements K and L should be assigned to the same station; both use a common component, and assigning them to the same station conserves storage space. Second, work elements H and I cannot be performed at the same station. Work-elements data are as follows.