[行列解析6.2.11]定義：行列の有向グラフの定義

A_1 =
\begin{bmatrix}
1 & 1 \\
1 & 1
\end{bmatrix},
\quad \\
{\Gamma}(A_1) =
\text{P1 → P2, P2 → P1 (全ての非ゼロ要素に対応)}

A_2 =
\begin{bmatrix}
0 & 1 \\
1 & 0
\end{bmatrix},
\quad
\\
{\Gamma}(A_2) =
\text{P1 → P2, P2 → P1 (非ゼロ要素に対応)}

A_3 =
\begin{bmatrix}
1 & 1 \\
0 & 0
\end{bmatrix},
\quad \\
\Gamma(A_3) =
\text{P1 → P2 (非ゼロ要素に対応)}

A_4 =
\begin{bmatrix}
4 & 2 & 1 \\
0 & 1 & 1 \\
0 & 0 & 1
\end{bmatrix},
\quad
\\
\Gamma(A_4) =
\text{P1 → P2, P1 → P3, P2 → P3 (非ゼロ要素に対応)}