A farmer has 10 elds in which corn will be planted. A primary concern is providing an adequate water supply to the elds. Supply of water itself is not the problem The farmer wishes, though, to minimize the cost of installing a waterpipe network that reaches all elds. A well will be drilled at one of the elds from which all others will be supplied. As shown in the below network diagram, each node represents a eld, and each arc represents a potential waterpipe link between respective elds. The numbers attached to each are represents costs (in 81,000s) associated with installing the link. Costs primarily reect the cost of pipe, labor. and equipment. Although cost is typically a linear function of pipe length. some differentials exist according to diiculty in laying the pipe.