
Linear Programming 21
FIGURE 1.5
Directed graph.
a generalization of the transportation problem in Example 1.6 and can be
formulated as a linear program. There are three types of nodes. The first type
of node is a supply node, and such a node i has a supply b
i
> 0 units of
the product. The second type of node is a demand node, and such a node
i requires a net amount |b
i
| of the product where b
i
< 0. The third type of
node is called a transshipment node and such a node does not have a supply
of products and do not require net any amount of the product and so b
i
= 0.
Transshipment nodes serve as nodes that a flow of products can go through
without leaving any ...