# Using ontology to infer labels for process model

I'm trying to implement a specific type of process mining, that has been presented in this thesis [link]. It is based on HMMs and generates a process model in form of a directed graph, where:

• Nodes are called intentions and correspond to hidden states
• Edges are called strategies and consist of different activities
• These activities correspond to the HMM's observable emissions
• Intentions can be fulfilled using different strategies

A user event log consisting of user IDs, timestamps and activities is used as input. The image below is an example of such a process model. The highlighted nodes and edges resemble the path that has been predicted using the Viterbi algorithm.

You can see that the graph's nodes and edges only carry numeric labels, which allow to distinguish between the different strategies and intentions. In order to make these labels more meaningful to the human reader, I'd like to infer some suitable labels.

My idea is to use an ontology to obtain those labels. After some research I figured out that I probably needed to do something that is generally referred to as "ontology learning". For this I would need to create some axioms in RDF/OWL format and then use these as input for a reasoner, that would infer an ontology.

Is this approach correct and reasonable to achieve my goal?

If this is the way to go, I will need some tool to generate axioms in an automated way. So far I couldn't find any tool that would do that completely out-of-the-box. Based on what I've seen so far I conclude that I would need to define some kind of mapping between the original data and the desired axioms. I took a closer look at protégé, which offers a plugin for spreadsheets. It seems to be based on the MappingMasterDSL project [link].

I've also found an interesting paper [link] on ontology learning where an RNN-based model is trained in a end-to-end fashion to translate definitory sentences into OWL formulae. BUT: My user event log data does not contain any natural sentences. Its activities are defined by tokens derived from HTML elements of the user interface. Therefore the RNN-based approach does not seem to be applicable here. (For the interested reader, the related project can be found here [link])

Isn't there really any easier way than hand-crafting the axioms' schema(ta)?

Assuming that I have created my axioms and inferred an ontology, I would like to use the strategies' (edges') observable activities (emissions) to infer a suitable label. I guess I would need to query my ontology somehow. I could use the activity names as parameters for my query and look for some related entities that reveal the desired label. I'm expecting something like:

"I have a strategy with ID=3, that strategy can be executed with actions a, b and c, give me all entities of the ontology, that have these actions as property value and show and give me all related labels for those entities"

But where would the data for the labels actually come from?

I think I'm missing some important step during the process of ontology learning. Where do I find an additional data source for the labels and how do I relate this data to my ontology's entities?

Also I'm wondering if there is a way to incorporate the inherent knowledge of the process model's topology into my ontology.