Incorrect handling of UML N-ary associations in RDF artefact generation #261
Description
Model2owl does not support N-ary associations. However, the current implementation of association transformation in model2owl fails to correctly identify and ignore UML N-ary associations if such occur in the input model. These are mistakenly interpreted as multiple binary associations due to the similarity in their XMI representations. As a result, RDF artefacts (core and restrictions) are generated incorrectly.
Steps to Reproduce:
- Use a UML model that includes a ternary (or more generally, N-ary where N > 2) association.
- Run the model2owl transformation to generate RDF artefacts.
An exemplary model demonstrating the issue.
Current Behaviour:
The following statements are generated in the restrictions artefact: toAC, toIns, toOtherC, and the TernaryTest association is reified into a class. Similarly, other statements are generated for the same “links” in the core artefact.
Expected Behaviour:
The ternary association TernaryTest should be ignored during RDF generation because N-ary associations (where N > 2) are not supported under SEMIC conventions for UML diagrams.
Suggested Fix:
Update the association transformation logic to detect N-ary associations and skip their processing entirely during RDF artefact generation.