Common Neighbourhood of an edge (Cn(E_ij)).

A contact E_ij (red) between nodes i (pink) and j (green) is shown. Let (N_i) be the neighbours of the i and (N_j) be neighbours of the j (grey). The CNb of edge (E_ij) is defined as

The nodes k₁, k₂ and k₃ (yellow) share edges with nodes i and j. The triangles k₁, k₂ and k₃ make with E_ij constitute the CNb triangles of E_ij.