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326 13 Cartography and Navigation

Fig. 13.5 The process specified by the WF-net of Fig. 13.3 viewed at different levels of abstrac-
tion. An activity and its corresponding connections are removed if the transition is less frequent
than the threshold. Both the atomic view (left) and the aggregate view (right) are shown for four
threshold values (0.3, 0.4, 0.6, and 1.0)

if activity l is very infrequent, it is not sufficient to hide it at a lower level: the
connection between z and x (i.e., place p5) should also be removed.
Figure 13.5 illustrates how processes can be viewed while taking into account
the frequencies of activities. As shown in Fig. 13.3, activities a, e, f , i, and j have
a frequency of 1, i.e., they are executed once for each case. Activities h and k are
executed for 60% of the cases, and activities b, g, and l are executed for 40% of
the cases. Activities c and d are least frequent and are executed for only 30% of
the cases. Assume that we would like to seamlessly simplify the model by progres-
sively leaving out more activities based on their frequencies. Figure 13.5 shows four
different levels. Here, we abstract from the detailed process logic and only show ac-
tivities and their connections. Moreover, we show the intensity of connections by