
362 Introduction to Computational Modeling
FIGURE 24.2: Graph of airline routes to Rio.
The problem can be formulated directly as a standard transportation problem,
using the data in Table 24.1 and Figure 24.2.
Let x
i j
denote the number of flights from node i to node j, and c
i j
the capacity
between nodes i and j. This problem has one supply point (source) and one demand
point (destination). The objective function can be written by observing that the max-
imum flow from node 1 to node 5 is actually the flow from node 1 to node 2, which
is represented by the variable x
12
. The objective function is then to maximize the
expression: z = x12.
To simplify the formulation ...