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elements with a lower value are contained in the subset adjacent and periphery regions. The
determining criterion for an element to be contained in the periphery subset is distance.
Given the criterion for the elements of the subsets of the C, A, P regions, the empirically
specified values defined in Section 4.3.2 are substituted in each subset. For the core regions from
equation (2):
C = {φ(updi ) ∈ C∣ φ(updi ) ≥ 500}
(2a)
where C represents a core region with an urban agglomerate equal to or greater than 500 people per
square kilometre.
Similarly, from equation (3) for an adjacent region,
A = {γ(updi) ∈ A(Θca)| 20 ≤ γ(updi) < 500}
(3a)
This indicates that a first order contiguous region contains an urban area with a minimum population
density of 20 but less than 500 people per square kilometre.
The criterion for a periphery region - a second order contiguous region - is identical to that of
an adjoining region, but differentiated from it by the distance criterion. From equation (4) we obtain:
P = {γ(updi) ∈ P(Θca < Θcp)∣ 20 ≤ Y(updt) < 500}
(4a)