Three classifiers are defined in the XES log shown in Fig. 4.8. Classifier Activity classifies events based on the concept:name attribute. Classifier Resource classifies events based on the org:resource attribute. Classifier Both classifies events based on two attributes: concept:name and org:resource. Recall that Definition 4.2 already introduced the concept of a classifier: an event e ∈ E is classified as e. For example, e = # resource(e) classifies events based on the resource executing the event