Can someone explain in simple terms to me what a directed acyclic graph is?

Question

Can someone explain in simple terms to me what a directed acyclic graph is? I have looked on Wikipedia but it doesn\'t really make me see its use in programming.

Answer 1

Directed Acyclic Graphs (DAG) have the following properties which distinguish them from other graphs:

1. Their edges show direction.
2. They don't have cycles.

Well, I can think of one use right now - DAG (known as Wait-For-Graphs - more technical details) are handy in detecting deadlocks as they illustrate the dependencies amongst a set of processes and resources (both are nodes in the DAG). Deadlock would happen when a cycle is detected.