Editing Unimodular matrix (section)

===Concrete examples===
1.  The following matrix is totally unimodular:

:<math>A=\left[\begin{array}{rrrrrr}
-1 & -1 & 0 & 0 & 0 & +1\\
+1 & 0 & -1 & -1 & 0 & 0\\
0 & +1 & +1 & 0 & -1 & 0\\
0 & 0 & 0 & +1 & +1 & -1
\end{array}\right].</math>

This matrix arises as the coefficient matrix of the constraints in the linear programming formulation of the [[Max-flow min-cut theorem|maximum flow]] problem on the following network:

[[Image:Graph for example adjacency matrix.svg]]

2.  Any matrix of the form
:<math>A=\left[\begin{array}{ccccc}
       & \vdots &        & \vdots \\
\dotsb & +1 & \dotsb & +1 & \dotsb \\
       & \vdots &        & \vdots \\
\dotsb & +1 & \dotsb & -1 & \dotsb \\
       & \vdots &        & \vdots
\end{array}\right].</math>
is ''not'' totally unimodular, since it has a square submatrix of determinant&nbsp;−2.