April 9, 2007 7:28 AM
Growth of common vocabulary - part 2
RDF properties represent relationship between two resources represented by URI (hereafter called web resources). RDF properties themselves are web resources, the relationship between RDF properties and web resources is described by the RDF vocabulary description language RDF Schema. RDF schema provides terms for writing web resource description in RDF.
class: is a group of resources, and the resource is an instance of the class. Therefore all RDF resources are instance of a class. property: since property is also a resource it is also an instance of a class.
| subject | property | subproperty | object |
|---|---|---|---|
| DSL broadband | speed | bitrate | 256Kbps |
| artist | speed | narration speed | 75w/min |
Here all <subject, object> tuples related by a subproperty are also related by the property.
RDF property domain : It defines the web resource sphere to which this property is applicable. The property may be applicable to more than one domain. RDF property range : It defines the possible values of this property.
The RDF schema terms class, property, subClassof, subPropertyOf, domain, range, type, and label, etc, can be used to define relationships between web resources. These RDF schema terms can also be used to integrate independently developed RDF vocabularies.
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Example: Property speed can be applied to more than one domain. Possible web resource spheres could be vehicles, internet connections, artist, etc. |
Thus RDF specifications provide mechanisms for independent vocabulary developments. However by using these mechanisms the semantic web will grow in an uncontrolled manner. This does not stop redundant definition of web resources. It is difficult to build web search tools and reasoning applications. If more than one RDF vocabulary with different range/domain for a property are found, they can be integrated by adding new domain/range for the property. One such database that can act as a repository of all independent RDF vocabulary triples is an alternative to the development method for a common vocabulary. Here the need for a common vocabulary is again emphasized for a fast, easy and smooth transition to Web 3.0.
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