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 k
1, k
2 and k
3 (yellow) share edges with nodes i and j. The triangles k
1, k
2 and k
3 make with E
ij constitute the CNb triangles of E
ij.