Editing Kirchhoff's theorem (section)

=== Kirchhoff's theorem for directed multigraphs ===
Kirchhoff's theorem can be modified to give the number of oriented spanning trees in directed multigraphs.
The matrix ''Q'' is constructed as follows:
* The entry ''q<sub>i,j</sub>'' for distinct ''i'' and ''j'' equals −''m'', where ''m'' is the number of edges from ''i'' to ''j'';
* The entry ''q<sub>i,i</sub>'' equals the indegree of ''i'' minus the number of loops at ''i''.
The number of oriented spanning trees rooted at a vertex ''i'' is the determinant of the matrix gotten by removing the ''i''th row and column of ''Q''