2) A few properties of the Laplacian. Consider an undirected and unweighted network graph G(V,E), with order Nv:=V, size N:=E, and adjacency matrix A. Let D=diag(d1,,dNv) be the degree matrix and L:=DA the Laplacian of G. Verify that 1:=[1,,1] is an eigenvector of L with associated eigenvalue 0