Request edge and assignment edge

A directed edge from process Pi to resource type Rj is denoted by PiRj; it signifies that process Pi requested an instance of resource type Rj and is currently waiting for that resource. A directed edge from resource type Rj to process Pi is denoted by RjPi, it signifies that an instance of resource type has been allocated to a process Pi. A directed edge PiRj is called a request edge. A directed edge RjPi is called an assignment edge.