to effect their desired boundary crossing. Between two adjacent regions, that desire
is based on how many inferiors there are in the home region and how many inferiors
there are in the region to be colonized.
The general layout of our model is shown in Fig. 34.8. The STELLA diagram of
Fig. 34.9 shows, as an example, how to calculate the amount of the three types of
space for the upper left-hand cell (Region 1) of the 3 Â 3 grid of nine interconnected
models. Only the inferior species in the adjacent regions to the right and below can
1
2
3
4
5
6
7
8
9
Fig. 34.8
Fig. 34.9
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34 Two-Species Colonization Model