Final answer:
The correct answer is d. adding additional nodes, as this option does not directly model flow restrictions but adjusts the network structure. To set flow restrictions, dummy arcs, dummy nodes, or dummy constraints are used.
Step-by-step explanation:
The question relates to the network flow problem, a concept in optimization within applied mathematics and computer science. When dealing with minimum or maximum flow restrictions, several modeling techniques can be utilized. However, the approach of adding dummy arcs or dummy nodes is common, as is creating dummy constraints to represent the flow restrictions mathematically.
Therefore, the correct answer is d. adding additional nodes. This option does not directly model flow restrictions. Instead, it would change the structure of the network itself, potentially altering the nature of the network and the path of the flow.
To clarify using an example, consider a network with two nodes connected by an arc that can only carry a certain amount of flow. To model a maximum flow restriction, one could add a dummy arc parallel to the existing one with a capacity that represents the maximum allowable flow. Similarly, dummy constraints could be added to the network model to ensure that the flow does not exceed a certain limit. Adding additional nodes does not directly impose a flow restriction but could be used to create more complex structures in the network.