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four types of adjacent regions, four types of periphery regions, and four types of island periphery
regions.
The following regional notation identifies the region types:
R = φ( x, y )
where the symbol R refers to region type: C, A, P, and IP as defined by the subset function φ, the
variable x equals the subset’s minimum population density criterion, and y represents the number of
urban areas in the region that meet the criterion. The y values representing the number of urban areas
are not included. Table 1 illustrates the generic classification of the regions. In the regional notation,
there is an inverse relation between the increasing values of x and the declining values of φ(updi)
exceeding the criterion for that subset.
[Figure 3]
The classification of the regions proceeds in the following manner. If x = 0, the region is
classified as an official (Eurostat) single city core region C or monocentric region, with no agricultural
production. For example, Brussels is a C, which indicates it is an official region with an urban area
whose size is equal to that of the county/region. If x = 1, and y = 0, the core region is symbolised by
C1 indicating that the region consists of a number of contiguous urban areas, with no agricultural
production, such as Greater Manchester, which is classified as a C1 region.
A core region, such as Düsseldorf is classified as C2:5 where x = 2, and y = 5. This indicates
that the core region of Düsseldorf has an urban population density equal to or greater than 2,000
people per square kilometre (x ≥ 500 = φ(updi)). It consists of five urban areas, each of which satisfies,
but significantly exceed, the criteria for that subset (See Table 1A). The core regions of West
Yorkshire (UK), Schwaben (D), and Lombardi (I), are classified as C3:1, since they consist of one
urban area with a population density of at least 1,000 people per square kilometre but less than 2,000.
A C3:5 classification represents a core region, such as North Holland (NL), composed of five urban
areas with a population density of 1,000 people per square kilometre but less than 2,000. Finally, the