Q. The RC 4000 system as well as other systems have defined a tree of processes (called a process tree) such that all the descendants of a process are given resources (objects) as well as access rights by their ancestors only. Therefore a descendant can never have the ability to do anything that its ancestors cannot do. The root of the tree is the OS (operating system) which has the ability to do anything. Presume the set of access rights was represented by an access matrix, A. A(x, y) defines the access rights of process x to object y. If x is a descendant of z, what is the relationship among A(x,y) and A(z,y) for an arbitrary object y?
Answer: A(x,y) is a subset of A(z,y).