# Integrating ISA and Part-of Domain Knowledge into Process Model Discovery
## 7 Experimental Work
finally, (3) each patient traversing the complete upper branch is forced to receive a _TPA ia Pre_, without administration of the therapy. Furthermore, such a patient begins _Rehab_ without any _Monitoring_. These situations are all valid reasons for discarding the model; therefore, the user backtracks to the model in Figure 8 and repeats the abstraction at level 2, choosing the alternative solution in Figure 9c. The result of this choice (node M5 of the versioning tree in Figure 16) is shown in Figure 11. This model leads to some improvements, compared to the one in Figure 10: the problem (1) has been solved (no patient can undergo all the therapies); the problem (3) is partially solved, since the direct transition from _TPA ia Proc_ to _Rehab_ is no longer forced, but optional (anyway, this option is still possible). The problem (2), however, remains in this model: patients traversing from the central branch for the administration of _TPA ia_ are forced to undergo _TPA ia Pre_ twice (_TPA ia pre_ is also included in _TPA ia Proc_). Due to these considerations, the user also discarded the model in Figure 11.  
After trying all the available solutions, it was clear to the user that the model in Figure 8 was not a suitable starting point to obtain an acceptable model at level 2. The problem resided in the intersecting paths in Figure 9; therefore, intuitively, a possible solution could be to not abstract both the _TPA ia Pre_ at level 3, but only one of them, in order to avoid conflict at level 2. With this strategy in mind, the user backtracked to the ground model in Figure 3 (node M1 of the versioning tree in Figure 16) and started the abstraction algorithm at level 3 of the KB. As before, the algorithm stopped at each detected abstraction waiting for input; the user accepted all the abstractions proposed by the system, except the _TPA ia Pre_ in the upper branch, abstracting only the _TPA ia Pre_ in the central branch. The obtained model is shown in Figure 12 (node M6 of the versioning tree in Figure 16). Figure 16.0 Process model abstracted at level 2 through the solution in Figure 9c. Figure 16.1 Process model interactively abstracted at level 3 with a different strategy. Figure 16.2 Process model abstracted at level 2 through the solution in Figure 10b. Starting from the model in Figure 12, the user asked the system to raise to abstraction level 2, accepting all the proposed abstractions, except the abstraction of _TPA ia Proc_ (_TPA ia Pre + TPA ia_) in the central branch. This model (node M7 of the versioning tree in Figure 16) is shown in Figure 16.3  
The model obtained with this strategy seems the most correct: it is not redundant, and it does not depict any unacceptable path, as seen before. This model also explains a clear picture of the general clinical process: after the _Evaluation_, the path at the top describes the treatment for patients eligible for _r-TPA_. In this path, the complete procedure for _r-TPA_ (_r-TPA Proc_) is performed, followed by the _Monitoring_ tests to verify the status of the patient after _r-TPA_ administration. After the _Monitoring_ (not detected in the previous models, and here executed at the right time), the model indicates two possible choices: rehabilitation (_Relab_) or, if the thrombus did not dissolve completely, _TPA ia_. In the latter case, in addition to the _Monitoring_ tests already carried out, the model states that an _AngioCT_ must be performed before proceeding with the administration of the _TPA ia_. Thus, the user accepts this model as the best solution so far. Furthermore, some generalizations can be investigated, since the _Monitoring_ activities seem to be performed at the end of each branch and merging them could simplify the process. The result of this generalization step is the model in Figure 14, corresponding to node M8 of the versioning tree in Figure 16.4  
The generalization step (i.e., merging all the _Monitoring_ activities) creates a more general model, at the cost of introducing a cycle.