To make the [adjacency matrix](https://forum.azimuthproject.org/discussion/comment/18927/#Comment_18927) notion painfully obvious.

\[ \left( \begin{array}{cc} 1 & 1 \\\\ 1 & 0 \end{array} \right) \]
\[ \left( \begin{array}{c | cc} s \rightarrow t & x & y \\\\ \hline x & \lbrace f \rbrace & \lbrace g \rbrace \\\\ y & \lbrace h \rbrace & \emptyset \end{array} \right) \]