quality:correction, structural:scholar_edition
Newer developments: a dynamic concept for CPT

This evolution can be modelled by means of the three major CPT theories: stage (a) is a system of von Thünen "isolated states"; stage (b) is a Christallerian hierarchical system; stage (c) is a Löschian post-hierarchical system. Furthermore, stage (b) corresponds to Christopher Alexander 's "tree" city, while (c) is similar to his "lattice" system (following his dictum "the city is not a tree").