- From: Saied Tazari <saied.tazari@zgdv.de>
- Date: Fri, 21 Nov 2003 13:01:38 +0100
- To: public-webont-comments@w3.org
As discussed in [1]: " Embedded resources result from either the part-of association – one of the fundamental concepts in object-oriented modeling – or the theorem of weak entity classes in database management. In UML class diagrams, for example, associations having a diamond on one side indicate that the class on that side represents composite objects having instances of the class on the other side as their parts. They go even further and say that if the diamond is darkened, then the instances of the class on the other side may never exist independently from instances of the class on the side of the diamond – quite similar to the concept of weak entity classes in database management. However, there is currently no standard way to specify part-of associations as such in RDF schema or OWL. CC/PP [8], as an RDF-based approach for articulation and exchange of contextual knowledge in profiles, has proposed the concept of components that can be seen as a solution for this problem. It was not consistent enough, though. It seems that the understanding of profiles in CC/PP is something like the old ".ini"-files in Windows(TM); i.e. all attributes must appear in some component and no attributes within components may have another component as value. None of these restrictions matched our requirements. This approach ignores the evolution of such config-files into tree structures like Windows(TM) registry. " To improve OWL in this regard, I suggest to add the following concepts: hasComponent|hasPart rdf:type TransitiveProperty componentOf|partOf rdf:type TransitiveProperty componentOf|partOf inverseOf hasComponent|hasPart WeakClass|WeakEntity rdfs:subClassOf Class hasContainerClass|dependsOn rdf:type TransitiveProperty hasContainerClass|dependsOn rdfs:domain WeakClass|WeakEntity hasContainerClass|dependsOn rdfs:range Class Other statements may also be added, e.g. about the cardinality of 'hasContainerClass' for instances of 'WeakClass' (it must be greater than 0). Of course, 'hasComponent' and 'componentOf' should be used in the descriptions of instances only when no additional semantics of the corresponding relation is known. Usually, however, one should introduce appropriate sub-properties of them and use the sub-properties in order to imply the additional semantics. Regards, -- Saied [1] Tazari, M.R. A Context-Oriented RDF Database. Semantic Web and Databases, Berlin (Germany), September 2003. http://www.zgdv.de/~stazari/publications/SWDB03.pdf
Received on Friday, 21 November 2003 07:01:58 UTC