Remember the di-graph from chapter 2? It is also possible to turn di-graphs into what are known as an incidence matrix.
Figure 0.17: A Di-Graph
\[ \begin{array}{ccccccccc} & 1 & 2 & 3 & 4 & 5 \\ A & 1 & 1 & 0 & 0 & 0 \\ B & 0 & 1 & 1 & 0 & 0 \\ C & 0 & 1 & 0 & 1 & 0 \\ D & 0 & 0 & 1 & 1 & 0 \\ E & 0 & 0 & 1 & 0 & 0 \\ \end{array} \]