For the DAC model discussed in Section 15.3, an alternative representation of the protection state is a directed graph. Each subject and each object in the protection state is represented by a node (a single node is used for an entity that is both subject and object). A directed line from a subject to an object indicates an access right, and the label on the link defines the access right.
a. Draw a directed graph that corresponds to the access matrix of Figure 15.3a.
b. Draw a directed graph that corresponds to the access matrix of Figure 15.5.
c. Is there a one-to-one correspondence between the directed graph representation and the access matrix representation? Explain.