Bill is building a project network that involves testing a prototype.

He must design the prototype $($activity $1),$ build the prototype $($activity $2),$ and test the prototype $($activity $3).$

Activity $1$ is the predecessor for activity $2$ and activity $2$ is the predecessor for activity

$3.$ If the prototype fails testing, Bill must redesign the prototype; therefore, activity $3$ is a predecessor for activity $1.$ This is an example of

Looping

Natural network flow

Conditional statements

Having more than one start node

$$ Good network development