Phylogenetic tree showing the lattice classification system and its conceptual evolution, from elementary cubic lattices (at the center) to compound and non-cubic lattices of progressively increasing levels of complexity. Black arrowed lines show pathways through which lattices at lower levels are combined or modified to produce new lattice types. Lattices contained within domains bounded by dark gray lines have the same network topology but varying network morphology. Two of the complex lattices residing at the periphery are illustrated in Figs. 2(h) and 2(i).