Point- and arc-reaching sets of vertices in a digraph

B. D. Acharya, K. A. Germina, Kumar Abhishek +2

In a digraph $D=(X,\mathcal{U})$, not necessarily finite, an arc $(x,y)\in \mathcal{U}$ is reachable from a vertex $u$ if there exists a directed walk $W$ that originates from…