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[protege-owl] A question on managing imports/merging ontologies

Matsokis Aristeidis aristeidis.matsokis at epfl.ch
Fri Jan 29 02:34:15 PST 2010


Dear All,

The idea is that we have an ontology that has a URI U where:
U = http://www.owl-ontologies.com/Ontology120.owl
A class of this ontology named "Product" will have as a full name:
http://www.owl-ontologies.com/Ontology120.owl#Product
Then, I make copies of this ontology and give them to my colleagues. Everyone populates his copy with instances, classes, DL rules etc. In the end we want to collect these copies and import/merge them together under one model. In this case there is a limitation which doesn't allow us acquire the desired result. It seems that this derives from the fact that the initial ontology O is defined by the URI U and the copies have exactly the same URI. (can this be the problem?)

In OWL 1 (Protégé 3.4) the merging of ontologies is not supported directly (As far as I have understood this is a limitation of OWL 1 and not of protégé. Correct?). However, by importing one or more ontologies into the other the total number of classes, properties, instances, DL rules, restrictions etc.
In OWL 2 (Protégé 4) after importing one or more ontologies into the other one is able to create a third ontology which will contain all the elements of the initial ontologies.
In my case there is a limitation which doesn't allow the user to acquire the desired result. The technical problem was that the initial ontology O is defined by the URI U and the copies have exactly the same URI. Therefore, in OWL 1 the tool loads the copy and sees it as recursive ontology. This means that it is already loaded. The tool does not perform any type of comparison between the two or more copies of the (same) ontology and hence, it does not load any element of the copy on the model.
In OWL 2 we have to import the ontology on protégé and then save the final project as merged, but since the first step is the same as in 3.4, the system does not load the elements of the copies. Therefore, a real merging of classes, instances, properties, DLs etc. cannot be performed.

In practice this means that if for example one ontology has a URI U where:
U = http://www.owl-ontologies.com/Ontology120.owl
A class of this ontology named "Product" will have as a full name:
http://www.owl-ontologies.com/Ontology120.owl#Product
The solution followed is indirect:

1.       Change the URI of each copy to a unique URI U'. All initial elements of the copy (classes, object and datatype properties, instances) keep their original URI U of ontology O.

2.       Set the default namespace of the copy the URI U to support extension

Do you have a more direct solution to suggest?
Is this a limitation of OWL 1 and 2 or of Protégé as a tool?
Is there a plan to support such cases in the future?

Thank you in advance for your time and support.

Aristeidis Matsokis


================
Aristeidis MATSOKIS
PhD Student-Research Assistant
EPFL STI-IGM-LICP
ME A1 380, Station 9
CH-1015 Lausanne
Switzerland
Tel:    +41 21 693 4359
Fax:   +41 21 693 3553
Mob: +41 76 232 0873

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