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Although the criterion for the adjacent region is theoretically identical to that of the periphery region,
the distinction between the two is determined by geographical distance from the core region. A
periphery region is, per definition, two regions removed from a core region. It is distinguished from
the adjacent region by definition and by the distance criterion.
The CAP model has postulated that a core region can be surrounded by a first-ring of adjacent
regions, and a second-ring of periphery regions. The number of adjacent and periphery regions in a
cluster can vary depending on the dispersion and density of urban agglomerates. A CAP cluster j is
defined in equation (10) as follows:
AP
CAP1 = Cj ∩∑A1 ∩∑Pj(θcp >θa ≥Θλp) = 0 (10)
j=1 j=1
To obtain a three-region CAP model, this analysis assumes that j = 1, and rewrite equation (10) to
include the theoretical regional criteria as follows:
CAP1 = φ(updi ) ∈ C1 ∩ γ(updi ) ∈ A1 ∩ γ(updi ) ∈ P1 (θcp > Θca ≥ Θap ) = 0 (11)
This expression (11) defines a three-region CAP model consisting of one core, one adjacent, and one
periphery region. The hierarchical link between the regions is determined by the population density
and distance criteria. The subscripts i refer to the number of urban areas in the respective regions.
4.3.5 Region and Urban Classification Outcomes
The classification procedure is based on the urban population density of cities in the
administrative regions as revealed by actual urban and demographic survey data. The regions are then
classified into core, adjacent, and periphery. The classification outcomes are listed in Table 1. The
major classifications of core, adjacent, and periphery are subcategorised into six types of core regions,