examples is acyclic if it has no directed cycles (see figure for some the transitive closure of digraph are the same as the vertices of is the digraph and such that the vertices of has an edge (uv)whenever has directed path from to that iswe define by starting with the digraph and adding in an extra edge (uvfor each and such that is reachable from (and there isn' already an edge (uvin figure examples of reachability in digraph(aa directed path from bos to lax is drawn in blue(ba directed cycle (ordmiadfwlaxordis shown in blueits vertices induce strongly connected subgraph(cthe subgraph of the vertices and edges reachable from ord is shown in blue(dremoving the dashed blue edges gives an acyclic digraph