Definition
A directed graph with no path that returns to an earlier node. DAGs naturally represent one-way dependency structures and work that must eventually complete without revisiting a prior state.
Distinguish it from nearby terms
Many production agent workflows are not DAGs because they retry, revise, ask for missing information, call tools repeatedly, or pause and resume. Those behaviors introduce cycles or external state transitions.
Check your understanding
If a workflow may revisit a prior node, it is not acyclic even if its happy path is drawn left to right.