Laplacian matrix

Laplacian, Spectral graph theory – Supra Laplacian matrix

• https://en.wikipedia.org/wiki/Laplacian_matrix

The basic Laplacian matrix (combinatorial Laplacian matrix) is defined as:

$$L = D - A$$

or

$$L_{i,j}:= \begin{cases} \deg(v_i) & \mbox{if}\ i = j \\ -1 & \mbox{if}\ i \neq j\ \mbox{and}\ v_i \mbox{ is adjacent to } v_j \\ 0 & \mbox{otherwise} \end{cases}$$