Assignment 2: OntoClean

The Problem

Let’s look at the following use case: a museum have been using a hierarchy of classes for many years to categorize the items in their collection. They have used the hierarchy only internally. Recently, they started thinking of publishing their collection online. They want to publish their hierarchy as well, not only so that other people can work with their metadata, but also to allow other people to link to and reuse their hierarchy. At this point, however, they realized that the meaning of some of their classes was unclear. Multiple interpretations of the same class were possible. They want this to be fixed before they publish the hierarchy, and decided to use OntoClean. The image below shows the original hierarchy.

Assignment Type: 

Research Report, 3 pages max.

The assignment

  1. Characterize each class in terms of the OntoClean properties “rigidity”, “identity” and “unity”. I.e., is the class rigid; does the class represent a unity; does the class have an identity criterion, If yes, which one?
  2. Re-construct the hierarchy based on this analysis.
  3. Construct an OWL specification of the backbone of the hierarchy.

Remarks & tips

  • Start with reading the OntoClean articles carefully.
  • Study in particular classes with multiple parents.
  • Insert only new classes if really needed.
  • Identity and unity criteria are often difficult to formulate precisely, but that does not prevent an object to have identity/unity.

Target results

  • Step 1: either an image clearly showing the rigidity/identity/unity of all classes in the hierarchy or an enumeration of all classes, specifying their rigidity/identity/unity.
  • Step 1: an explanation of your rationale for step 1. This can be short.
  • Step 2: an image of your new hierarchy
  • Step 3: OWL specification file

Submission deadline:

Friday 16 November, 23:59 CET

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11 Responses to Assignment 2: OntoClean

  1. Julien L. says:

    Are the arrows between Chair, Wooden Chair and Garden Chair really meant to look like they do in the diagram? So the diagram states that a Chair IS Wooden Chair and a Garden Chair? Or is it meant the other way around: both Wooden Chairs and Garden Chairs ARE chairs?

  2. Thijs says:

    The way I read the assignment, the whole hierarchy represent classes. But, it seems logical to me that Vincent van Gogh is an instance of the class Painter. So I guess i’m confused on whether I am free to interpret Van Gogh as an instance, or should I follow the way I read the assignment and threat everything as a class?

  3. George Kyriacou says:

    Does anyone when assigning metaproperties to classes take into consideration the metaproperty dependency ? coz every example i ve seen this property is also assigned.

    • Julien L. says:

      Not sure of what you mean.. :S
      Can you elaborate?

    • Julien L. says:

      If you mean “a class with X rigidity cannot be a subclass of a class with Y rigidity” and that kind of considerations, I would not consider it while working on the first step of the assignment: since the hierarchy which is given might be wrong, I feel like some of these “dependencies” might not be respected 😉

      Once you decided for each and every class about its rigidity, unity and identity, then you can consider this kind of “dependency” and this is how you will spot the misuses of the subsumbtion relationship. I guess that’s the whole point with Ontoclean.

      Looking at my mindmap: https://dl.dropbox.com/u/61281858/OntoClean.png , I would say that the first step of the assignment is simply studying the “formal notions” (rigidity, identity and unity) for every class. The second step is to spot the “misuses of subsumption”, using the analysis of step 1, and build a new hierarchy!

  4. George Kyriacou says:

    Yes i agree. At the first step we have to assign metaproperties for each class (rigidity,unity identity) and explain why we assign these particular metaproperties. At the second step we have to make the analysis and provide the clean ontology. This is a very helpful tutorial (http://www.loa.istc.cnr.it/Papers/GuarinoWeltyOntoCleanv3.pdf) . Finally, if we ever get there, in the third step we have to remove from the ontology all classes which they dont have +R metaproperty and keep only the rigid classes and according to this analysis provide the owl file of the backbone of the ontology. Now concerning my previous question i am wondering if it is necessary to take into consideration the dependence metaproperty as it explained in the paper i gave above.

  5. Julien L. says:

    I did not, but I guess you’re free to use OntoClean the way you want to, since our teachers care more about your explanation of why you did things a certain way more than how you actually did it.

  6. Richard H. says:

    We created our new hierachie and also implement it with protege.
    How do I get now the OWL specifications from protege or do we have to handle in the .owl file?
    Any help or suggestions?

    • Julien L. says:

      I am really not sure about this.

      I inserted a screenshot like in assignment 1, but I guess the OWL file can also be interesting. I think I heard Willem answering to another group that you could give the OWL file as well, but I’m not sure if that was meant “the whole file as an appendix” or two files in a ZIP folder.

      I would suggest to send a mail to the teachers, since they tend to answer mails but not comments on the WordPress, and to keep us updated! 😉

      • stefania says:

        well, to be honest, previous time we have pasted the screenshots in the assignment doc and also put the OWL files in a folder, and all together submitted in a zip folder 🙂 so in that way covered every aspect..
        I agree with both of you that this was not clear, too.. You can always do it this way, skipping mails and waiting for answers 😉

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