Tutorial: Getting Started with Protege-Frames
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Modifying the hierarchy
At this point, you will see that Author and Columnist are at the same level (siblings) in the hierarchy, while News_Service and Editor are subclasses of Author. Conceptually, however, News_Service, Editor, and Columnist are all at the same level of generality, while Author is a more general concept. This goes against a principle of good ontology design: all the siblings in a hierarchy (except for the ones at the root) should be at the same level of generality. Therefore, we want to modify our hierarchy to make Columnist a subclass of Author, which will more accurately reflect the underlying structure. To modify the hierarchy by making Columnist a subclass of Author:
  1. Click on Columnist and drag it over the Author class (Author will be outlined), then release.



  2. Columnist is moved and now appears as a subclass of Author.



In this case, the mismatch may have been obvious. However, when you create your own ontologies, the development process itself can reveal differences or parallels that were not clear at the beginning. Therefore it is likely as you go along that you will rearrange the hierarchy, as well as create and delete classes, to better model the concepts you are trying to capture.