or a position in an XML document. The reason for adding them is that this way it
becomes easy to refer to a particular case or event. In fact, for simple algorithms like the α-algorithm, Definition 4.3 is a bit of overkill. See for example Table 1.2 in Sect. 1.4 showing the essential information used to construct a Petri net. If one is just interested in activity names (or some other classifier), the definition can be simplified drastically as is shown next.