Figure 2

Problematic clusters with non-linear topological structure. (a) Identification of non-linearity of cluster topological structure: presence of vertices with not too small ranks (e.g., more than 2) points to non-short offshoots from the selected diametric path (marked in bold line). (b) Splitting clusters into sub-clusters having linear topological structure. See also Additional File 1, Section 4.