Reachability in a graph
= Reachability in a graph
= Reachability
{synonym}
A vertex $v$ is reachable from $u$ if a finite path leads from $u$ to $v$, respecting edge directions in a directed <graph>. For a finite graph, <graph search> decides <reachability> by maintaining the <set> of discovered vertices; every step discovers a new vertex or examines an edge, so the procedure terminates.