$s(i)=a_i$ for any $i \in \{1,\dots,n\}$.

XES Event Logs
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We use the XES standard definition of event logs, an overview of which is shown in Figure \[fig:XES\_metamodel\]. XES defines an event *log* as a set of *traces*, which in itself is a sequence of *event*s. The log, traces and events can all contain one or more *attribute*s, which consist of a *key* and a *value* of a certain type. Event or trace attributes may be *global*, which indicates that the attribute needs to be defined for each event or trace respectively. A log contains one or more *classifier*s, which can be seen as labeling functions on the events of a log, defined on global event attributes. *Extension*s define a set of attributes on log, trace, or event level, in such a way that the semantics of these attributes are clearly defined. One can view XES extensions as a specification of attributes that events, traces, or event logs themselves frequently contain. XES defines the following standard extensions:

Concept

:   [Specifies the generally understood name of the event/trace/log (attribute ’Concept:name’).]{}

Lifecycle

:   [Specifies the lifecycle phase (attribute ’Lifecycle:transition’) that the event represents in a transactional model of their generating activity. The 