-Conventional process discovery algorithms are fully automated and work as a black box from the user's perspective. Event data is fed into the discovery algorithm, and a process model is returned. Interactive process discovery is about breaking this black-box approach of conventional process discovery and involving the user during the discovery, i.e., adopting the principles of hybrid intelligence in process discovery. The central idea is to exploit the user's knowledge of the process to be discovered within the discovery phase to obtain better models. The software tool Cortado allows for the incremental discovery of a process model based on user-selected process behavior. In this paper, we present the implementation of sub-model freezing, i.e., a novel form of user interaction during incremental process discovery, in Cortado. Index Terms-process mining, interactive process discovery, process models, hybrid intelligence
Process discovery, a key discipline of process mining [
In [
https://cortado.fit.fraunhofer.de/ Process Model “Under Construction” “Frozen” “Frozen”
Sub-Model Sub-Model incrementally marks process
model parts as “frozen” User/ Modeler incrementally selects process behavior (a trace) not yet described by the process model
Cortado: Freezing-Enabled
Incremental
Process Discovery
Modified Process Model ′ describing the selected process behavior and previously added
behavior “Frozen” Sub-Model
“Frozen”
Sub-Model
Event Data
Fig. 1. Conceptual idea of sub-model freezing during incremental process
discovery. Figure adapted from [
freezing within incremental process discovery. Afterwards, we focus on the implementation of said technique in Cortado.
The theoretical foundations of sub-model freezing are
introduced in [
antee that these sub-models will be present in the new model M 0 in identical form. Note that the incrementally discovered process model M 0 describes the selected trace variant plus previously selected trace variants. After one iteration, the user can incrementally add further trace variants to the model under construction. Note that the incrementally discovered model M 0 is used as an input in the next iteration, visualized by the dotted arc from M 0 to M in Figure 1. Further, the user can change (a) Without freezing: Initial model that describes the first two variants (b) Without freezing: Process model after the third variant has been incremen(indicated by green check-marks, which are located left to each variant) tally added to the model shown in Figure 2a (c) With freezing: Initial model as shown in Figure 2a with frozen process (d) With freezing: Process model after the third variant has been incrementally model part (frozen subtree is marked blue) added to the model shown in Figure 2c. which sub-models are frozen in each iteration.
In Figure 2, we present screenshots of Cortado that are demonstrating the described incremental process discovery approach once without freezing (Figure 2a and 2b) and once with freezing (Figure 2c and 2d). In both cases, we use the same event data and the same initial model that describes the first two variants from the variant explorer, cf. Figure 2a and
formalism. We refer to [
Figure 2b shows the process tree after adding the third variant from the variant explorer to the initial process tree.
W_Afhandelen leads. In Figure 2c, we see the same initial process tree where the user marked a subtree as frozen, highlighted in blue colors. After adding the the third variant to the initial process tree with frozen subtree, we observe that the resulting process tree is different compared to the one obtained without freezing. This time, the algorithm added an optional activity labeled with W_Afhandelen leads before the frozen subtree is executed. Note that the frozen subtree has not been altered by the algorithm, compared to the execution without freezing (Figure 2b). Further, note that both discovered process trees, i.e., with/without freezing, describe the three selected trace variants shown; however, they structurally differ.
freezing—a novel form of user interaction within incremental process discovery—in Cortado. Further, we highlighted the difference between using and not using the freezing option with an example.